case study infancy development

Infancy and Toddlerhood

Why understand human development during infancy.

Welcome to the story of development from infancy through toddlerhood; from birth until about two years of age. Did you ever wonder how babies grow from tiny, helpless infants into well-developed and independent adults?  It doesn’t happen overnight, but the process begins right from day one. Infancy is a time when tremendous growth, coordination, and mental development occur. Most infants learn to walk, manipulate objects, and can form basic words by the end of infancy. By 5 months a baby will have doubled its birth weight and tripled its birth weight by the first year. By the age of 2, a baby’s weight will have quadrupled!

Researchers have given this part of the life span more attention than any other period, perhaps because changes during this time are so dramatic and so noticeable. We know that much of what happens during these years provide a foundation for one’s life to come, however, it has been a rgued that the significance of development during these years has been overstated (Bruer, 1999). Nevertheless, this is a period of life that contemporary educators, healthcare pro viders, and parents have focused on quite heavily. It is also a time period that can be tricky to study—how do we learn about infant speech when they cannot articulate their thoughts or feelings? For example, through research we know that infants understand speech much earlier than their bodies have matured enough to physically perform it; thus it is evident that their speech patterns develop before the physical growth of their vocal cords is adequate to facilitate speech.

In this module, we will examine the rapid physical growth and development of infants, look at the influences on physical growth and cognitive development, then turn our attention toward emotional and social development in the early years of life. The early years are a time of rapid physical, cognitive, social, and emotional development, which have a direct effect on a baby’s overall development and the adult they will become.

What you’ll learn to do: describe physical growth and development in infants and toddlers

We’ll begin this section by reviewing the physical development that occurs during infancy, a period that starts at birth and continues until the second birthday. We’ll see how this time involves rapid growth, not only in observable changes like height and weight but also in brain development.

Next, we will explore reflexes. At birth, infants are equipped with a number of reflexes, which are involuntary movements in response to stimulation. We will explore these innate reflexes and then consider how these involuntary reflexes are eventually modified through experiences to become voluntary movements and the basis for motor development as skills emerge that allow an infant to grasp food, rollover, and take the first step.

Third, we will explore the baby’s senses. Every sense functions at birth—newborns use all of their senses to attend to everything and every person. We will explore how infants’ senses develop and how sensory systems like hearing and vision operate, and how infants take in information through their senses and transform it into meaningful information.

Finally, since growth during infancy is so rapid and the consequence of neglect can be severe, we will consider some of the influences on early physical growth, particularly the importance of nutrition.

Learning outcomes

• Summarize overall physical growth patterns during infancy
• Describe the growth of the brain during infancy
• Explain gross and fine motor skills in infants
• Explain newborn perceptual abilities
• Explain the merits of breastfeeding
• Discuss the importance of nutrition to early physical growth, including nutritional concerns for infants and toddlers such as marasmus and kwashiorkor
• Describe sleep concerns for infants
• Explain the vaccination debate and its consequences

Physical Growth and Brain Development in Infancy

Overall physical growth.

By the time an infant is 4 months old, it usually doubles in weight, and by one year has tripled its birth weight. By age 2, the weight has quadrupled. The average length at 12 months (one-year-old) typically ranges from 28.5-30.5 inches. The average length at 24 months (two years old) is around 33.2-35.4 inches (CDC, 2010).

Monitoring Physical Growth

As mentioned earlier, growth is so rapid in infancy that the consequences of neglect can be severe. For this reason, gains are closely monitored. At each well-baby check-up, a baby’s growth is compared to that baby’s previous numbers. Often, measurements are expressed as a percentile  from 0 to 100, which compares each baby to other babies the same age. For example, weight at the 40th percentile means that 40 percent of all babies weigh less, and 60 percent weigh more. For any baby, pediatricians and parents can be alerted early just by watching percentile changes. If an average baby moves from the 50th percentile to the 20th, this could be a sign of failure to thrive, which could be caused by various medical conditions or factors in the child’s environment. The earlier the concern is detected, the earlier intervention and support can be provided for the infant and caregiver.

Body Proportions

Another dramatic physical change that takes place in the first several years of life is a change in body proportions. The head initially makes up about 50 percent of a person’s entire length when developing in the womb. At birth, the head makes up about 25 percent of a person’s length (just imagine how big your head would be if the proportions remained the same throughout your life!). In adulthood, the head comprises about 15 percent of a person’s length. Imagine how difficult it must be to raise one’s head during the first year of life! And indeed, if you have ever seen a 2- to 4-month-old infant lying on their stomach trying to raise the head, you know how much of a challenge this is.

The Brain in the First Two Years

Some of the most dramatic physical change that occurs during this period is in the brain. At birth, the brain is about 25 percent of its adult weight, and this is not true for any other part of the body. By age 2, it is at 75 percent of its adult weight, at 95 percent by age 6, and at 100 percent by age 7 years.

Communication within the central nervous system (CNS), which consists of the brain and spinal cord, begins with nerve cells called neurons . Neurons connect to other neurons via networks of nerve fibers called axons and dendrites . Each neuron typically has a single axon and numerous dendrites which are spread out like branches of a tree (some will say it looks like a hand with fingers). The axon of each neuron reaches toward the dendrites of other neurons at intersections called synapses , which are critical communication links within the brain. Axons and dendrites do not touch, instead, electrical impulses in the axons cause the release of chemicals called neurotransmitters which carry information from the axon of the sending neuron to the dendrites of the receiving neuron. 

While most of the brain’s 100 to 200 billion neurons are present at birth, they are not fully mature. Each neural pathway forms thousands of new connections during infancy and toddlerhood. During the next several years, dendrites , or connections between neurons, will undergo a period of transient exuberance or temporary dramatic growth ( exuberant  because it is so rapid and  transient  because some of it is temporary). There is a proliferation of these dendrites during the first two years so that by age 2, a single neuron might have thousands of dendrites. After this dramatic increase, the neural pathways that are not used will be eliminated through a process called pruning , thereby making those that are used much stronger. It is thought that pruning causes the brain to function more efficiently, allowing for mastery of more complex skills (Hutchinson, 2011). Transient exuberance occurs during the first few years of life, and pruning continues through childhood and into adolescence in various areas of the brain. This activity is occurring primarily in the cortex or the thin outer covering of the brain involved in voluntary activity and thinking. 

The prefrontal cortex, located behind the forehead, continues to grow and mature throughout childhood and experiences an additional growth spurt during adolescence. It is the last part of t he brain to mature and will eventually comprise 85 percent of the brain’s weight. Experience will shape which of these connections are maintained and which of these are lost. Ultimately, about 40 percent of these connections will be lost (Webb, Monk, & Nelson, 2001). As the prefrontal cortex matures, the child is increasingly able to regulate or control emotions, to plan activity, to strategize, and have better judgment. Of course, this is not fully accomplished in infancy and toddlerhood but continues throughout childhood and adolescence.

Another major change occurring in the central nervous system is the development of myelin , a coating of fatty tissues around the axon of the neuron. Myelin helps insulate the nerve cell and speed the rate of transmission of impulses from one cell to another. This enhances the building of neural pathways and improves coordination and control of movement and thought processes. The development of myelin continues into adolescence but is most dramatic during the first several years of life.

Motor and Sensory Development

From reflexes to voluntary movements.

Every basic motor skill (any movement ability) develops over the first two years of life. The sequence of motor skills first begins with reflexes . Infants are equipped with a number of reflexes, or involuntary movements in response to stimulation, and some are necessary for survival. These include the breathing reflex, or the need to maintain an oxygen supply (this includes hiccups, sneezing, and thrashing reflexes), reflexes that maintain body temperature (crying, shivering, tucking the legs close, and pushing away blankets), the sucking reflex, or automatically sucking on objects that touch their lips, and the rooting reflex, which involves turning toward any object that touches the cheek (which manages feeding, including the search for a nipple). Other reflexes are not necessary for survival, but signify the state of brain and body functions. Some of these include the Babinski reflex (toes fan upward when feet are stroked), the stepping reflex (babies move their legs as if to walk when feet touch a flat surface), the palmar grasp (the infant will tightly grasp any object placed in its palm), and the Moro reflex (babies will fling arms out and then bring to the chest if they hear a loud noise). These movements occur automatically and are signals that the infant is functioning well neurologically. Within the first several weeks of life, these reflexes are replaced with voluntary movements or motor skills.

Motor development

Motor development occurs in an orderly sequence as infants move from reflexive reactions (e.g., sucking and rooting) to more advanced motor functioning. This development proceeds in a cephalocaudal  (from head-down) and proximodistal  (from center-out) direction. For instance, babies first learn to hold their heads up, then sit with assistance, then sit unassisted, followed later by crawling, pulling up, cruising, and then walking. As motor skills develop, there are certain developmental milestones that young children should achieve. For each milestone, there is an average age, as well as a range of ages in which the milestone should be reached. An example of a developmental milestone is a baby holding up its head. Babies on average are able to hold up their head at 6 weeks old, and 90% of babies achieve this between 3 weeks and 4 months old. If a baby is not holding up his head by 4 months old, he is showing a delay. On average, most babies sit alone at 7 months old. Sitting involves both coordination and muscle strength, and 90% of babies achieve this milestone between 5 and 9 months old (CDC, 2018). If the child is displaying delays on several milestones, that is a reason for concern, and the parent or caregiver should discuss this with the child’s pediatrician. Some developmental delays can be identified and addressed through early intervention.

Link to Learning

It is important to understand that there is a range of normal for reaching developmental milestones.  It should not be a competition between parents whose child reached which milestones first. Each child will develop at their own pace based on many different factors. However, if a delay is diagnosed there are early invention services that are available in most states.  Review the services that are available in Arizona .

Gross Motor Skills

Gross motor skills  are  voluntary movements that involve the use of large muscle groups and are typically large movements of the arms, legs, head, and torso. These skills begin to develop first. Examples include moving to bring the chin up when lying on the stomach, moving the chest up, rocking back and forth on hands and knees. But it also includes exploring an object with one’s feet as many babies do, as early as 8 weeks of age, if seated in a carrier or other device that frees the hips. This may be easier than reaching for an object with the hands, which requires much more practice (Berk, 2007). And sometimes an infant will try to move toward an object while crawling and surprisingly move backward because of the greater amount of strength in the arms than in the legs!

Fine Motor Skills

Fine motor skills are more exact movements of the hands and fingers and include the ability to reach and grasp an object. These  skills  focus on the muscles in the fingers, toes, and eyes, and enable coordination of small actions (e.g., grasping a toy, writing with a pencil, and using a spoon). Newborns cannot grasp objects voluntarily but do wave their arms toward objects of interest. At about 4 months of age, the infant is able to reach for an object, first with both arms and within a few weeks, with only one arm. Grasping an object involves the use of the fingers and palm, but no thumbs. Stop reading for a moment and try to grasp an object using the fingers and the palm. How does that feel? How much control do you have over the object? If it is a pen or pencil, are you able to write with it? Can you draw a picture? The answer is, probably not. Use of the thumb comes at about 9 months of age when the infant is able to grasp an object using the forefinger and thumb ( the pincer grasp ). This ability greatly enhances the ability to control and manipulate an object, and infants take great delight in this newfound ability. They may spend hours picking up small objects from the floor and placing them in containers. By 9 months, an infant can also watch a moving object, reach for it as it approaches, and grab it. This is quite a complicated set of actions if we remember how difficult this would have been just a few months earlier.

The Centers for Disease Control and Prevention (CDC) describes the developmental milestones for children from 2 months through 5 years old. After reviewing the information, take the CDC’s Developmental Milestones quiz  to see how well you recall what you’ve learned. If you are a parent with concerns about your child’s development, contact your pediatrician.

Good nutrition in a supportive environment is vital for an infant’s healthy growth and development. Remember, from birth to 1 year, infants triple their weight and increase their height by half, and this growth requires good nutrition. For the first 6 months, babies are fed breast milk or formula. Starting good nutrition practices early can help children develop healthy dietary patterns. Infants need to receive nutrients to fuel their rapid physical growth. Malnutrition during infancy can result in not only physical but also cognitive and social consequences. Without proper nutrition, infants cannot reach their physical potential.

Introducing Solid Foods

Breast milk or formula is the only food a newborn needs, and the American Academy of Pediatrics recommends exclusive breastfeeding for the first six months after birth. Solid foods can be introduced from around six months onward when babies develop stable sitting and oral feeding skills but should be used only as a supplement to breast milk or formula. By six months, the gastrointestinal tract has matured, solids can be digested more easily, and allergic responses are less likely. The infant is also likely to develop teeth around this time, which aids in chewing solid food. Iron-fortified infant cereal, made of rice, barley, or oatmeal, is typically the first solid introduced due to its high iron content. Cereals can be made of rice, barley, or oatmeal. Generally, salt, sugar, processed meat, juices, and canned foods should be avoided.

Though infants usually start eating solid foods between 4 and 6 months of age, more and more solid foods are consumed by a growing toddler. Pediatricians recommended introducing foods one at a time, and for a few days, in order to identify any potential food allergies. Toddlers may be picky at times, but it remains important to introduce a variety of foods and offer food with essential vitamins and nutrients, including iron, calcium, and vitamin D.

Malnutrition

About 9 million children in the United States are malnourished (Children’s Welfare, 1998). More still suffer from milk anemia , a condition in which milk consumption leads to a lack of iron in the diet. The prevalence of iron deficiency anemia in 1- to 3-year-old children seems to be increasing (Kazal, 2002). The body gets iron through certain foods. Toddlers who drink too much cow’s milk may also become anemic if they are not eating other healthy foods that have iron. This can be due to the practice of giving toddlers milk as a pacifier when resting, riding, walking, and so on. Appetite declines somewhat during toddlerhood and a small amount of milk (especially with added chocolate syrup) can easily satisfy a child’s appetite for many hours. The calcium in milk interferes with the absorption of iron in the diet as well. There is also a link between iron deficiency anemia and diminished mental, motor, and behavioral development. In the second year of life, iron deficiency can be prevented by the use of a diversified diet that is rich in sources of iron and vitamin C, limiting cow’s milk consumption to less than 24 ounces per day, and providing a daily iron-fortified vitamin. 

Children in developing countries and countries experiencing the harsh conditions of war are at risk for two major types of malnutrition.  Infantile marasmus  refers to starvation due to a lack of calories and protein. Children who do not receive adequate nutrition lose fat and muscle until their bodies can no longer function. Babies who are breastfed are much less at risk of malnutrition than those who are bottle-fed. After weaning, children who have diets deficient in protein may experience  kwashiorkor  or the “disease of the displaced child,” often occurring after another child has been born and taken over breastfeeding. This results in a loss of appetite and swelling of the abdomen as the body begins to break down the vital organs as a source of protein

The website  Zero to Three  has more information on infant sleep patterns and habits. Feel free to explore their multiple topics on the subject.

Immunizations

Preventing communicable diseases from early infancy is one of the major tasks of the Public Health System in the USA. Infants mouth every single object they find as one of their typical developmental tasks. They learn through their senses and tasting objects stimulates their brain and provides a sensory experience as well as learning.

Infants have much contact with dirty surfaces. They lay on a carpet that most likely has been contaminated by adults walking on it; they mouth keys, rattles, toys, and books; they crawl on the floor; they hold on to furniture to walk, and much more. How do we prevent infants from getting sick? One possible answer is  immunizations .

Many decades ago, our society struggled to find vaccines and cures for illnesses such as Polio, whooping cough, and many other medical conditions. A few decades ago parents started changing their minds on the need to vaccinate children. Some children are not vaccinated for valid medical reasons, but some states allow a child to be unvaccinated because of a parent’s personal or religious beliefs. At least 1 in 14 children is not vaccinated. What is the outcome of not vaccinating children? Some of the preventable illnesses are returning. Fortunately, each vaccinated child stops the transmission of the disease, a phenomenon called herd immunity . Usually, if 90% of the people in a community (a herd) are immunized, no one dies of that disease.

In 2017, Community Care Licensing in California, the agency that regulates childcare centers, changed regulations. Before it was possible for parents to opt-out of vaccinations due to personal beliefs, but this changed after Governor Brown signed a Bill in 2016 to only exclude children from being vaccinated if there were medical reasons. Furthermore, all personnel working with children must be immunized.

Read more information about vaccinations at the website  Shots for School.

What you’ll learn to do: explain cognitive development in infants and toddlers

In addition to rapid physical growth, young children also exhibit significant development of their cognitive abilities, particularly in language acquisition and in the ability to think and reason. You already learned a little bit about Piaget’s theory of cognitive development, and in this section, we’ll apply that model to cognitive tasks during infancy and toddlerhood. Piaget described intelligence in infancy as sensorimotor or based on direct, physical contact where infants use senses and motor skills to taste, feel, pound, push, hear, and move in order to experience the world. These basic motor and sensory abilities provide the foundation for the cognitive skills that will emerge during the subsequent stages of cognitive development.

• Describe each of Piaget’s theories and stages of sensorimotor intelligence
• Explain learning and memory abilities in infants and toddlers
• Describe stages of language development during infancy
• Compare theories of language development in toddlers
• Explain the procedure, results, and implications of Hamlin and Wynn’s research on moral reasoning in infants

Cognitive Development

Cognitive development in children.

In order to adapt to the evolving environment around us, humans rely on cognition, both adapting to the environment and also transforming it. In general, all theorists studying cognitive development address three main issues:

• The typical course of cognitive development
• The unique differences between individuals
• The mechanisms of cognitive development (the way genetics and environment combine to generate patterns of change)

The Cognitive Perspective: The Roots of Understanding

Cognitive theories focus on how our mental processes or cognitions change over time. The theory of cognitive development  is a comprehensive theory about the nature and development of human intelligence first developed by Jean Piaget. It is primarily known as a developmental stage theory, but in fact, it deals with the nature of knowledge itself and how humans come gradually to acquire it, construct it, and use it. Moreover, Piaget claims that cognitive development is at the center of the human organism and language is contingent on cognitive development. Let’s learn more about Piaget’s views about the nature of intelligence and then dive deeper into the stages that he identified as critical in the developmental process.

Stages of Cognitive Development

Like Freud and Erikson, Piaget thought development unfolded in a series of stages approximately associated with age ranges. He proposed a theory of cognitive development that unfolds in four stages: sensorimotor, preoperational, concrete operational, and formal operational.

Piaget and Sensorimotor Intelligence

How do infants connect and make sense of what they are learning? Remember that Piaget believed that we are continuously trying to maintain cognitive equilibrium, or balance, between what we see and what we know (Piaget, 1954). Children have much more of a challenge in maintaining this balance because they are constantly being confronted with new situations, new words, new objects, etc. All this new information needs to be organized, and a framework for organizing information is referred to as a schema . Children develop schemas through the processes of assimilation and accommodation .

For example, 2-year-old Deja learned the schema for dogs because her family has a Poodle. When Deja sees other dogs in her picture books, she says, “Look mommy, dog!” Thus, she has assimilated them into her schema for dogs. One day, Deja sees a sheep for the first time and says, “Look mommy, dog!” Having a basic schema that a dog is an animal with four legs and fur, Deja thinks all furry, four-legged creatures are dogs. When Deja’s mom tells her that the animal she sees is a sheep, not a dog, Deja must accommodate her schema for dogs to include more information based on her new experiences. Deja’s schema for dog was too broad since not all furry, four-legged creatures are dogs. She now modifies her schema for dogs and forms a new one for sheep.

Let’s examine the transition that infants make from responding to the external world reflexively as newborns, to solving problems using mental strategies as two-year-olds. Piaget called this first stage of cognitive development  sensorimotor intelligence  (the sensorimotor period) because infants learn through their senses and motor skills. He subdivided this period into six substages:

Substages of Sensorimotor Intelligence

For an overview of the substages of sensorimotor thought, it helps to group the six substages into pairs. The first two substages involve the infant’s responses to its own body, call primary circular reactions . During the first month first (substage one), the infant’s senses, as well as motor reflexes are the foundation of thought.

Substage One:  Reflexive Action (Birth through 1st month)

This active learning begins with automatic movements or reflexes (sucking, grasping, staring, listening). A ball comes into contact with an infant’s cheek and is automatically sucked on and licked. But this is also what happens with a sour lemon, much to the infant’s surprise! The baby’s first challenge is to learn to adapt the sucking reflex to bottles or breasts, pacifiers or fingers, each acquiring specific types of tongue movements to latch, suck, breath, and repeat. This adaptation demonstrates that infants have begun to make sense of sensations. Eventually, the use of these reflexes becomes more deliberate and purposeful as they move onto substage two.

Substage Two:  First Adaptations to the Environment (1st through 4th months)

Fortunately, within a few days or weeks, the infant begins to discriminate between objects and adjust responses accordingly as reflexes are replaced with voluntary movements. An infant may accidentally engage in a behavior and find it interesting, such as making a vocalization. This interest motivates trying to do it again and helps the infant learn a new behavior that originally occurred by chance. The behavior is identified as circular and primary because it centers on the infant’s own body. At first, most actions have to do with the body, but in months to come, will be directed more toward objects. For example, the infant may have different sucking motions for hunger and others for comfort (i.e. sucking a pacifier differently from a nipple or attempting to hold a bottle to suck it).

The next two substages (3 and 4), involve the infant’s responses to objects and people, called secondary circular reactions.  Reactions are no longer confined to the infant’s body and are now interactions between the baby and something else.

Substage Three:  Repetition (4th through 8th months)

During the next few months, the infant becomes more and more actively engaged in the outside world and takes delight in being able to make things happen by responding to people and objects. Babies try to continue any pleasing event. Repeated motion brings particular interest as the infant is able to bang two lids together or shake a rattle and laugh. Another example might be to clap their hands when a caregiver says “patty-cake.” Any sight of something delightful will trigger efforts for interaction.

Substage Four:  New Adaptations and Goal-Directed Behavior (8th through 12th months)

Now the infant becomes more deliberate and purposeful in responding to people and objects and can engage in behaviors that others perform and anticipate upcoming events. Babies may ask for help by fussing, pointing, or reaching up to accomplish tasks, and work hard to get what they want. Perhaps because of continued maturation of the prefrontal cortex, the infant becomes capable of having a thought and carrying out a planned, goal-directed activity such as seeking a toy that has rolled under the couch or indicating that they are hungry. The infant is coordinating both internal and external activities to achieve a planned goal and begins to get a sense of social understanding. Piaget believed that at about 8 months (during substage 4), babies first understood the concept of object permanence, which is the realization that objects or people continue to exist when they are no longer in sight.

The last two stages (5 and 6), called tertiary circular reactions , consist of actions (stage 5) and ideas (stage 6) where infants become more creative in their thinking.

Substage Five:  Active Experimentation of “Little Scientists” (12th through 18th months)

The toddler is considered a “little scientist” and begins exploring the world in a trial-and-error manner, using motor skills and planning abilities. For example, the child might throw their ball down the stairs to see what happens or delight in squeezing all of the toothpaste out of the tube. The toddler’s active engagement in experimentation helps them learn about their world. Gravity is learned by pouring water from a cup or pushing bowls from high chairs. The caregiver tries to help the child by picking it up again and placing it on the tray. And what happens? Another experiment! The child pushes it off the tray again causing it to fall and the caregiver to pick it up again! A closer examination of this stage causes us to really appreciate how much learning is going on at this time and how many things we come to take for granted must actually be learned. This is a wonderful and messy time of experimentation and most learning occurs by trial and error.

Substage Six:  Mental Representations (18th month to 2 years of age)

The child is now able to solve problems using mental strategies, to remember something heard days before and repeat it, to engage in pretend play, and to find objects that have been moved even when out of sight. Take, for instance, the child who is upstairs in a room with the door closed, supposedly taking a nap. The doorknob has a safety device on it that makes it impossible for the child to turn the knob. After trying several times to push the door or turn the doorknob, the child carries out a mental strategy to get the door opened – he knocks on the door! Obviously, this is a technique learned from the past experience of hearing a knock on the door and observing someone opening the door. The child is now better equipped with mental strategies for problem-solving. Part of this stage also involves learning to use language. This initial movement from the “hands-on” approach to knowing about the world to the more mental world of stage six marked the transition to preoperational thinking, which you’ll learn more about in a later module.

Development of Object Permanence

A critical milestone during the sensorimotor period is the development of object permanence. Introduced during substage 4 above, object permanence is the understanding that even if something is out of sight, it continues to exist. The infant is now capable of making attempts to retrieve the object. Piaget thought that, at about 8 months, babies first understand the concept of objective permanence, but some research has suggested that infants seem to be able to recognize that objects have permanence at much younger ages (even as young as 4 months of age). Other researchers, however, are not convinced (Mareschal & Kaufman, 2012). It may be a matter of “grasping vs. mastering” the concept of objective permanence. Overall, we can expect children to grasp the concept that objects continue to exist even when they are not in sight by around 8 months old, but memory may play a factor in their consistency. Because toddlers (i.e., 12–24 months old) have mastered object permanence, they enjoy games like hide-and-seek, and they realize that when someone leaves the room they will come back (Loop, 2013). Toddlers also point to pictures in books and look in the appropriate places when you ask them to find objects.

Learning and Memory Abilities in Infants

Memory is central to cognitive development. Our memories form the basis for our sense of self, guide our thoughts and decisions, influence our emotional reactions, and allow us to learn (Bauer, 2008).

It is thought that Piaget underestimated memory ability in infants (Schneider, 2015). This belief came in part from findings that adults rarely recall personal events from before the age of 3 years (a phenomenon that is known as infantile or childhood amnesia ). However, research with infants and young children has made it clear that they can and do form memories of events. 

As mentioned when discussing the development of infant senses, within the first few weeks of birth, infants recognize their caregivers by face, voice, and smell. Sensory and caregiver memories are apparent in the first month, motor memories by 3 months, and then, at about 9 months, more complex memories including language (Mullally & Maguire, 2014). There is an agreement that memory is fragile in the first months of life, but that improves with age. Repeated sensations and brain maturation are required in order to process and recall events (Bauer, 2008). Infants remember things that happened weeks and months ago (Mullally & Maguire, 2014), although they most likely will not remember it decades later. From the cognitive perspective, this has been explained by the idea that the lack of linguistic skills of babies and toddlers limit their ability to mentally represent events; thereby, reducing their ability to encode memory. Moreover, even if infants do form such early memories, older children and adults may not be able to access them because they may be employing very different, more linguistically based, retrieval cues than infants used when forming the memory. 

Language Development

Given the remarkable complexity of a language, one might expect that mastering a language would be an especially arduous task; indeed, for those of us trying to learn a second language as adults, this might seem to be true. However, young children master language very quickly with relative ease. B. F. Skinner (1957) proposed that language is learned through reinforcement. Noam Chomsky (1965) criticized this behaviorist approach, asserting instead that the mechanisms underlying language acquisition are biologically determined. The use of language develops in the absence of formal instruction and appears to follow a very similar pattern in children from vastly different cultures and backgrounds. It would seem, therefore, that we are born with a biological predisposition to acquire a language (Chomsky, 1965; Fernández & Cairns, 2011). Moreover, it appears that there is a critical period for language acquisition, such that this proficiency at acquiring language is maximal early in life; generally, as people age, the ease with which they acquire and master new languages diminishes (Johnson & Newport, 1989; Lenneberg, 1967; Singleton, 1995).

Children begin to learn about language from a very early age (Table 1). In fact, it appears that this is occurring even before we are born. Newborns show a preference for their mother’s voice and appear to be able to discriminate between the language spoken by their mother and other languages. Babies are also attuned to the languages being used around them and show preferences for videos of faces that are moving in synchrony with the audio of spoken language versus videos that do not synchronize with the audio (Blossom & Morgan, 2006; Pickens, 1994; Spelke & Cortelyou, 1981).

Each language has its own set of phonemes that are used to generate morphemes , words, and so on. Babies can discriminate among the sounds that make up a language (for example, they can tell the difference between the “s” in vision and the “ss” in fission); early on, they can differentiate between the sounds of all human languages, even those that do not occur in the languages that are used in their environments. However, by the time that they are about 1 year old, they can only discriminate among those phonemes that are used in the language or languages in their environments (Jensen, 2011; Werker & Lalonde, 1988; Werker & Tees, 1984).

HOW DOES SOCIOECONOMIC STATUS AFFECT LANGUAGE DEVELOPMENT?

The achievement gap refers to the persistent difference in grades, test scores, and graduation rates that exist among students of different ethnicities, races, and—in certain subjects—sexes (Winerman, 2011). Research suggests that these achievement gaps are strongly influenced by differences in socioeconomic factors that exist among the families of these children. While the researchers acknowledge that programs aimed at reducing such socioeconomic discrepancies would likely aid in equalizing the aptitude and performance of children from different backgrounds, they recognize that such large-scale interventions would be difficult to achieve. Therefore, it is recommended that programs aimed at fostering aptitude and achievement among disadvantaged children may be the best option for dealing with issues related to academic achievement gaps (Duncan & Magnuson, 2005).

Low-income children perform significantly more poorly than their middle- and high-income peers on a number of educational variables: They have significantly lower standardized test scores, graduation rates, and college entrance rates, and they have much higher school dropout rates. There have been attempts to correct the achievement gap through state and federal legislation, but what if the problems start before the children even enter school?

Psychologists Betty Hart and Todd Risley (2006) spent their careers looking at the early language ability and progression of children in various income levels. In one longitudinal study, they found that although all the parents in the study engaged and interacted with their children, middle- and high-income parents interacted with their children differently than low-income parents. After analyzing 1,300 hours of parent-child interactions, the researchers found that middle- and high-income parents talk to their children significantly more, starting when the children are infants. By 3 years old, high-income children knew almost double the number of words known by their low-income counterparts, and they had heard an estimated total of 30 million more words than the low-income counterparts (Hart & Risley, 2003). And the gaps only become more pronounced. Before entering kindergarten, high-income children score 60% higher on achievement tests than their low-income peers (Lee & Burkam, 2002).

There are solutions to this problem. At the University of Chicago, experts are working with low-income families, visiting them at their homes, and encouraging them to speak more to their children on a daily and hourly basis. Other experts are designing preschools in which students from diverse economic backgrounds are placed in the same classroom. In this research, low-income children made significant gains in their language development, likely as a result of attending the specialized preschool (Schechter & Byeb, 2007). What other methods or interventions could be used to decrease the achievement gap? What types of activities could be implemented to help the children of your community or a neighboring community?

Infant Communication

Intentional Vocalizations

Infants begin to vocalize and repeat vocalizations within the first couple of months of life. That gurgling, musical vocalization called cooing can serve as a source of entertainment to an infant who has been laid down for a nap or seated in a carrier on a car ride. Cooing serves as practice for vocalization. It also allows the infant to hear the sound of their own voice and try to repeat sounds that are entertaining. Infants also begin to learn the pace and pause of conversation as they alternate their vocalization with that of someone else and then take their turn again when the other person’s vocalization has stopped. Cooing initially involves making vowel sounds like “oooo.” Later, as the baby moves into babbling (see below), consonants are added to vocalizations such as “nananananana.”

Babbling and Gesturing

Between 6 and 9 months, infants begin making even more elaborate vocalizations that include the sounds required for any language. Guttural sounds, clicks, consonants, and vowel sounds stand ready to equip the child with the ability to repeat whatever sounds are characteristic of the language heard. These babies repeat certain syllables (ma-ma-ma, da-da-da, ba-ba-ba), a vocalization called babbling because of the way it sounds. Eventually, these sounds will no longer be used as the infant grows more accustomed to a particular language. Deaf babies also use gestures to communicate wants, reactions, and feelings. Because gesturing seems to be easier than vocalization for some toddlers, sign language is sometimes taught to enhance one’s ability to communicate by making use of the ease of gesturing. The rhythm and pattern of language are used when deaf babies sign just as when hearing babies babble.

At around ten months of age, infants can understand more than they can say. You may have experienced this phenomenon as well if you have ever tried to learn a second language. You may have been able to follow a conversation more easily than to contribute to it.

Holophrastic Speech

Children begin using their first words at about 12 or 13 months of age and may use partial words to convey thoughts at even younger ages. These one-word expressions are referred to as holophrastic speech ( holophrase ). For example, the child may say “ju” for the word “juice” and use this sound when referring to a bottle. The listener must interpret the meaning of the holophrase. When this is someone who has spent time with the child, interpretation is not too difficult. They know that “ju” means “juice” which means the baby wants some milk! But, someone who has not been around the child will have trouble knowing what is meant. Imagine the parent who exclaims to a friend, “Ezra’s talking all the time now!” The friend hears only “ju da ga” which, the parent explains, means “I want some milk when I go with Daddy.”

Underextension

A child who learns that a word stands for an object may initially think that the word can be used for only that particular object. Only the family’s Irish Setter is a “doggie.” This is referred to as underextension. More often, however, a child may think that a label applies to all objects that are similar to the original object. In overextension, all animals become “doggies,” for example.

First words and cultural influences

The first words for English-speaking children tend to be nouns. The child labels objects such as a cup or a ball. In a verb-friendly language such as Chinese, however, children may learn more verbs. This may also be due to the different emphasis given to objects based on culture. Chinese children may be taught to notice action and relationships between objects while children from the United States may be taught to name an object and its qualities (color, texture, size, etc.). These differences can be seen when comparing interpretations of art by older students from China and the United States.

Vocabulary growth spurt

One-year-olds typically have a vocabulary of about 50 words. But by the time they become toddlers, they have a vocabulary of about 200 words and begin putting those words together in telegraphic speech (short phrases). This language growth spurt is called the  naming explosion because many early words are nouns (persons, places, or things).

Two-word sentences and telegraphic speech

Words are soon combined and 18-month-old toddlers can express themselves further by using phrases such as “baby bye-bye” or “doggie pretty.” Words needed to convey messages are used, but the articles and other parts of speech necessary for grammatical correctness are not yet included. These expressions sound like a telegraph (or perhaps a better analogy today would be that they read like a text message) where unnecessary words are not used. “Give baby ball” is used rather than “Give the baby the ball.” Or a text message of “Send money now!” rather than “Dear Mother. I really need some money to take care of my expenses.” You get the idea.

Child-directed speech

Why is a horse a “horsie”? Have you ever wondered why adults tend to use “baby talk” or that sing-song type of intonation and exaggeration used when talking to children? This represents a universal tendency and is known as child-directed speech or motherese or parentese. It involves exaggerating the vowel and consonant sounds, using a high-pitched voice, and delivering the phrase with great facial expression. Why is this done? It may be in order to clearly articulate the sounds of a word so that the child can hear the sounds involved. Or it may be because when this type of speech is used, the infant pays more attention to the speaker and this sets up a pattern of interaction in which the speaker and listener are in tune with one another. When I demonstrate this in class, the students certainly pay attention and look my way. Amazing! It also works in the college classroom!

Theories of Language Development

How is language learned? Each major theory of language development emphasizes different aspects of language learning: that infants’ brains are genetically attuned to language, that infants must be taught and that infants’ social impulses foster language learning. The first two theories of language development represent two extremes in the level of interaction required for language to occur (Berk, 2007).

Chomsky and the language acquisition device

This theory posits that infants teach themselves and that language learning is genetically programmed. The view is known as nativism  and was advocated by Noam Chomsky, who suggested that infants are equipped with a neurological construct referred to as the language acquisition device (LAD) , which makes infants ready for language. The LAD allows children, as their brains develop, to derive the rules of grammar quickly and effectively from the speech they hear every day. Therefore, language develops as long as the infant is exposed to it. No teaching, training, or reinforcement is required for language to develop. Instead, language learning comes from a particular gene, brain maturation, and the overall human impulse to imitate.

Skinner and reinforcement

This theory is the opposite of Chomsky’s theory because it suggests that infants need to be taught language. This idea arises from behaviorism. Learning theorist, B. F. Skinner, suggested that language develops through the use of reinforcement. Sounds, words, gestures, and phrases are encouraged by following the behavior with attention, words of praise, treats, or anything that increases the likelihood that the behavior will be repeated. This repetition strengthens associations, so infants learn the language faster as parents speak to them often. For example, when a baby says “ma-ma,” the mother smiles and repeats the sound while showing the baby attention. So, “ma-ma” is repeated due to this reinforcement.

Social pragmatics

Another language theory emphasizes the child’s active engagement in learning the language out of a need to communicate. Social impulses foster infant language because humans are social beings and we must communicate because we are dependent on each other for survival. The child seeks information, memorizes terms, imitates the speech heard from others and learns to conceptualize using words as language is acquired. Tomasello &  Herrmann (2010) argue that all human infants, as opposed to chimpanzees, seek to master words and grammar in order to join the social world. Many would argue that all three of these theories (Chomsky’s argument for nativism, conditioning, and social pragmatics) are important for fostering the acquisition of language (Berger, 2004).

Moral Reasoning in Infants

The foundation of moral reasoning in infants.

The work of Lawrence Kohlberg was an important start to modern research on moral development and reasoning. However, Kohlberg relied on a specific method: he presented moral dilemmas and asked children and adults to explain what they would do and—more importantly—why they would act in that particular way. Kohlberg found that children tended to make choices based on avoiding punishment and gaining praise. But children are at a disadvantage compared to adults when they must rely on language to convey their inner thoughts and emotional reactions, so what they say may not adequately capture the complexity of their thinking.

Starting in the 1980s, developmental psychologists created new methods for studying the thought processes of children and infants long before they acquire language. One particularly effective method is to present children with puppet shows to grab their attention and then record nonverbal behaviors, such as looking and choosing, to identify children’s preferences or interests.

A research group at Yale University has been using the puppet show technique to study the moral thinking of children for much of the past decade. What they have discovered has given us a glimpse of surprisingly complex thought processes that may serve as the foundation of moral reasoning.

Remember that Lawrence Kohlberg thought that children at this age—and, in fact, through 9 years of age—are primarily motivated to avoid punishment and seek rewards. Neither Kohlberg nor Carol Gilligan nor Jean Piaget was likely to predict that infants would develop preferences based on the type of behavior shown by other individuals.

What you’ll learn to do: explain emotional and social development during infancy

Psychosocial development occurs as children form relationships, interact with others, and understand and manage their feelings. In emotional and social development, forming healthy attachments is very important and is the major social milestone of infancy.  Attachment is a long-standing connection or bond with others. Developmental psychologists are interested in how infants reach this milestone. They ask questions such as: how do parent and infant attachment bonds form? How does neglect affect these bonds? What accounts for children’s attachment differences?

• Describe emotional development and self-awareness during infancy
• Contrast styles of attachment
• Use Erikson’s theory to characterize psychosocial development during infancy

Emotional Development and Attachment

Emotional development.

At birth, infants exhibit two emotional responses: attraction and withdrawal. They show attraction to pleasant situations that bring comfort, stimulation, and pleasure. And they withdraw from unpleasant stimulation such as bitter flavors or physical discomfort. At around two months, infants exhibit social engagement in the form of social smiling as they respond with smiles to those who engage their positive attention. Pleasure is expressed as laughter at 3 to 5 months of age, and displeasure becomes more specific to fear, sadness, or anger (usually triggered by frustration) between ages 6 and 8 months. Where anger is a healthy response to frustration, sadness, which appears in the first months as well, usually indicates withdrawal (Thiam et al., 2017).

As reviewed above, infants progress from reactive pain and pleasure to complex patterns of socioemotional awareness, which is a transition from basic instincts to learned responses. Fear is not always focused on things and events; it can also involve social responses and relationships. The fear is often associated with the presence of strangers or the departure of significant others known respectively as  stranger wariness and separation anxiety , which appear sometime between 6 and 15 months. And there is even some indication that infants may experience jealousy as young as 6 months of age (Hart & Carrington, 2002).

Stranger wariness actually indicates that brain development and increased cognitive abilities have taken place. As an infant’s memory develops, they are able to separate the people that they know from the people that they do not. The same cognitive advances allow infants to respond positively to familiar people and recognize those that are not familiar. Separation anxiety  also indicates cognitive advances and is universal across cultures. Due to the infant’s increased cognitive skills, they are able to ask reasonable questions like “Where is my caregiver going?” “Why are they leaving?” or “Will they come back?” Separation anxiety usually begins around 7-8 months and peaks around 14 months, and then decreases. Both stranger wariness and separation anxiety represent important social progress because they not only reflect cognitive advances but also growing social and emotional bonds between infants and their caregivers.

As we will learn through the rest of this module, caregiving does matter in terms of infant emotional development and emotional regulation.  Emotional regulation  can be defined by two components: emotions as regulating and emotions as regulated. The first, “emotions as regulating,” refers to changes that are elicited by activated emotions (e.g., a child’s sadness eliciting a change in parent response). The second component is labeled “emotions as regulated,” which refers to the process through which the activated emotion is itself changed by deliberate actions taken by the self (e.g., self-soothing, distraction) or others (e.g., comfort).

Throughout infancy, children rely heavily on their caregivers for emotional regulation; this reliance is labeled co-regulation, as parents and children both modify their reactions to the other based on the cues from the other. Caregivers use strategies such as distraction and sensory input (e.g., rocking, stroking) to regulate infants’ emotions. Despite their reliance on caregivers to change the intensity, duration, and frequency of emotions, infants are capable of engaging in self-regulation strategies as young as 4 months old. At this age, infants intentionally avert their gaze from overstimulating stimuli. By 12 months, infants use their mobility in walking and crawling to intentionally approach or withdraw from stimuli.

Throughout toddlerhood, caregivers remain important for the emotional development and socialization of their children, through behaviors such as labeling their child’s emotions, prompting thought about emotion (e.g., “why is the turtle sad?”), continuing to provide alternative activities/distractions, suggesting coping strategies, and modeling coping strategies. Caregivers who use such strategies and respond sensitively to children’s emotions tend to have children who are more effective at emotion regulation, are less fearful and fussy, more likely to express positive emotions, easier to soothe, more engaged in environmental exploration, and have enhanced social skills in the toddler and preschool years.

Self-awareness

During the second year of life, children begin to recognize themselves as they gain a sense of the self as an object. The realization that one’s body, mind, and activities are distinct from those of other people is known as self-awareness (Kopp, 2011). The most common technique used in research for testing self-awareness in infants is a mirror test known as the “Rouge Test.” The rouge test works by applying a dot of rouge (colored makeup) on an infant’s face and then placing them in front of the mirror. If the infant investigates the dot on their nose by touching it, they are thought to realize their own existence and have achieved self-awareness. A number of research studies have used this technique and shown self-awareness to develop between 15 and 24 months of age.  Some researchers also take language such as “I, me, my, etc.” as an indicator of self-awareness.

Cognitive psychologist Philippe Rochat (2003) described a more in-depth developmental path in acquiring self-awareness through various stages.  He described self-awareness as occurring in five stages beginning from birth.

Once a child has achieved self-awareness , the child is moving toward understanding social emotions such as guilt, shame or embarrassment, and pride, as well as sympathy and empathy. These will require an understanding of the mental state of others which is acquired around age 3 to 5 and will be explored in the next module (Berk, 2007).

Psychosocial development occurs as children form relationships, interact with others, and understand and manage their feelings. In social and emotional development, forming healthy attachments is very important and is the major social milestone of infancy. Attachment is a long-standing connection or bond with others. Developmental psychologists are interested in how infants reach this milestone. They ask questions such as: How do parent and infant attachment bonds form? How does neglect affect these bonds? What accounts for children’s attachment differences?

Researchers Harry Harlow, John Bowlby, and Mary Ainsworth conducted studies designed to answer these questions. In the 1950s, Harlow conducted a series of experiments on monkeys. He separated newborn monkeys from their mothers. Each monkey was presented with two surrogate mothers. One surrogate mother was made out of wire mesh, and she could dispense milk. The other surrogate mother was softer and made from cloth: This monkey did not dispense milk. Research shows that the monkeys preferred the soft, cuddly cloth monkey, even though she did not provide any nourishment. The baby monkeys spent their time clinging to the cloth monkey and only went to the wire monkey when they needed to be feed. Prior to this study, the medical and scientific communities generally thought that babies become attached to the people who provide their nourishment. However, Harlow (1958) concluded that there was more to the mother-child bond than nourishment. Feelings of comfort and security are the critical components of maternal-infant bonding, which leads to healthy psychosocial development.

Building on the work of Harlow and others, John Bowlby developed the concept of attachment theory. He defined attachment as the affectional bond or tie that an infant forms with the mother (Bowlby, 1969). He believed that an infant must form this bond with a primary caregiver in order to have normal social and emotional development. In addition, Bowlby proposed that this attachment bond is very powerful and continues throughout life. He used the concept of a secure base to define a healthy attachment between parent and child (1988). A secure base is a parental presence that gives children a sense of safety as they explore their surroundings. Bowlby said that two things are needed for a healthy attachment: The caregiver must be responsive to the child’s physical, social, and emotional needs; and the caregiver and child must engage in mutually enjoyable interactions (Bowlby, 1969).

While Bowlby thought attachment was an all-or-nothing process, Mary Ainsworth’s (1970) research showed otherwise. Ainsworth wanted to know if children differ in the ways they bond, and if so, how. To find the answers, she used the Strange Situation procedure to study attachment between mothers and their infants (1970). In the Strange Situation, the mother (or primary caregiver) and the infant (age 12-18 months) are placed in a room together.  There are toys in the room, and the caregiver and child spend some time alone in the room. After the child has had time to explore their surroundings, a stranger enters the room. The mother then leaves her baby with the stranger. After a few minutes, she returns to comfort her child.

Based on how the toddlers responded to the separation and reunion, Ainsworth identified three types of parent-child attachments: secure, avoidant, and resistant (Ainsworth & Bell, 1970). A fourth style, known as disorganized attachment, was later described (Main & Solomon, 1990).

The most common type of attachment—also considered the healthiest—is called secure attachment . In this type of attachment, the toddler prefers their parent over a stranger. The attachment figure is used as a secure base to explore the environment and is sought out in times of stress. Securely attached children were distressed when their caregivers left the room in the Strange Situation experiment, but when their caregivers returned, the securely attached children were happy to see them. Securely attached children have caregivers who are sensitive and responsive to their needs.

With avoidant attachment , the child is unresponsive to the parent, does not use the parent as a secure base, and does not care if the parent leaves. The toddler reacts to the parent the same way they react to a stranger. When the parent does return, the child is slow to show a positive reaction. Ainsworth theorized that these children were most likely to have a caregiver who was insensitive and inattentive to their needs (Ainsworth, Blehar, Waters, & Wall, 1978).

In cases of resistant attachment , children tend to show clingy behavior, but then they reject the attachment figure’s attempts to interact with them (Ainsworth & Bell, 1970). These children do not explore the toys in the room, appearing too fearful. During separation in the Strange Situation, they become extremely disturbed and angry with the parent. When the parent returns, the children are difficult to comfort. Resistant attachment is thought to be the result of the caregivers’ inconsistent level of response to their child.

Finally, children with disorganized attachment behaved oddly in the Strange Situation. They freeze, run around the room in an erratic manner, or try to run away when the caregiver returns (Main & Solomon, 1990). This type of attachment is seen most often in kids who have been abused or severely neglected. Research has shown that abuse disrupts a child’s ability to regulate their emotions.

While Ainsworth’s research has found support in subsequent studies, it has also met criticism. Some researchers have pointed out that a child’s temperament (which we discuss next) may have a strong influence on attachment (Gervai, 2009; Harris, 2009), and others have noted that attachment varies from culture to culture, a factor that was not accounted for in Ainsworth’s research (Rothbaum, Weisz, Pott, Miyake, & Morelli, 2000; van Ijzendoorn & Sagi-Schwartz, 2008).

Attachment styles vary in the amount of security and closeness felt in the relationship and they can change with new experiences. The type of attachment fostered in parenting styles varies by culture as well. For example, German parents value independence and Japanese mothers are typically by their children’s sides. As a result, the rate of insecure-avoidant attachments is higher in Germany and insecure-resistant attachments are higher in Japan. These differences reflect cultural variation rather than true insecurity, however (van Ijzendoorn and Sagi, 1999).  Keep in mind that methods for measuring attachment styles have been based on a model that reflects middle-class, US values and interpretation. Newer methods for assessing attachment styles involve using a Q-sort technique in which a large number of behaviors are recorded on cards and the observer sorts the cards in a way that reflects the type of behavior that occurs within the situation.

Attachment is classified into four types: A, B, C, and D. Ainsworth’s original schema differentiated only three types of attachment (types A, B, and C), but, as mentioned above, later researchers discovered a fourth category (type D). As we explore styles of attachment below, consider how these may also be evidenced in adult relationships. We’ll come back to this idea in later modules.

Types of Attachments

A secure attachment (type B) is one in which the child feels confident that their needs will be met in a timely and consistent way. The caregiver is the base for exploration, providing assurance, and enabling discovery. In North America, this interaction may include an emotional connection in addition to adequate care. However, even in cultures where mothers do not talk, cuddle, and play with their infants, secure attachments can develop (LeVine et. al., 1994). Secure attachments can form provided the child has consistent contact and care from one or more caregivers. Consistency of contacts may be jeopardized if the infant is cared for in a daycare with a high turn-over of caregivers or if institutionalized and given little more than basic physical care. And while infants who, perhaps because of being in orphanages with inadequate care, have not had the opportunity to attach in infancy can form initial secure attachments several years later, they may have more emotional problems of depression or anger, or be overly friendly as they make adjustments (O’Connor et. al., 2003).

Insecure Resistant/Ambivalent

Insecure-resistant/ambivalent (type C) attachment style is marked by insecurity and resistance to engaging in activities or play away from the caregiver. It is as if the child fears that the caregiver will abandon them and clings accordingly. (Keep in mind that clingy behavior can also just be part of a child’s natural disposition or temperament and does not necessarily reflect some kind of parental neglect.) The child may cry if separated from the caregiver and also cry upon their return. They seek constant reassurance that never seems to satisfy their doubt. This type of insecure attachment might be a result of not having their needs met in a consistent or timely way. Consequently, the infant is never sure that the world is a trustworthy place or that he or she can rely on others without some anxiety. A caregiver who is unavailable, perhaps because of marital tension, substance abuse, or preoccupation with work, may send a message to the infant they cannot rely on having their needs met. A caregiver who attends to a child’s frustration can help teach them to be calm and to relax. But an infant who receives only sporadic attention when experiencing discomfort may not learn how to calm down.

Insecure-Avoidant

Insecure-avoidant  (type A) is an attachment style marked by insecurity. This style is also characterized by a tendency to avoid contact with the caregiver and with others. This child may have learned that needs typically go unmet and learns that the caregiver does not provide care and cannot be relied upon for comfort, even sporadically. An insecure-avoidant child learns to be more independent and disengaged. Such a child might sit passively in a room filled with toys until it is time to go.

Disorganized

Disorganized attachment (type D) represents the most insecure style of attachment and occurs when the child is given mixed, confused, and inappropriate responses from the caregiver. For example, a mother who suffers from schizophrenia may laugh when a child is hurting or cry when a child exhibits joy. The child does not learn how to interpret emotions or to connect with the unpredictable caregiver.

How common are the attachment styles among children in the United States? It is estimated that about 65 percent of children in the United States are securely attached. Twenty percent exhibit avoidant styles and 10 to 15 percent are resistant. Another 5 to 10 percent may be characterized as disorganized.

Erikson’s Stages for Infants and Toddlers

Autonomy vs. shame and doubt (Will)

Autonomy vs. Shame (Will) —As toddlers (ages 1–3 years) begin to explore their world, they learn that they can control their actions and act on their environment to get results. They begin to show clear preferences for certain elements of the environment, such as food, toys, and clothing. A toddler’s main task is to resolve the issue of autonomy vs. shame and doubt by working to establish independence. This is the “me do it” stage. For example, we might observe a budding sense of autonomy in a 2-year-old child who wants to choose her clothes and dress herself. Although her outfits might not be appropriate for the situation, her input in such basic decisions has an effect on her sense of independence. If denied the opportunity to act on her environment, she may begin to doubt her abilities, which could lead to low self-esteem and feelings of shame.

As the child begins to walk and talk, an interest in independence or autonomy replaces their concern for trust. The toddler tests the limits of what can be touched, said, and explored. Erikson believed that toddlers should be allowed to explore their environment as freely as safety allows and, in doing so, will develop a sense of independence that will later grow to self-esteem, initiative, and overall confidence. If a caregiver is overly anxious about the toddler’s actions for fear that the child will get hurt or violate others’ expectations, the caregiver can give the child the message that they should be ashamed of their behavior and instill a sense of doubt in their abilities. Parenting advice based on these ideas would be to keep your toddler safe, but let them learn by doing. A sense of pride seems to rely on doing rather than being told how capable one is (Berger, 2005).

Theory of Psychosexual Development

During the anal stage , which coincides with toddlerhood and potty-training, the child is taught that some urges must be contained and some actions postponed. There are rules about certain functions and when and where they are to be carried out. The child is learning a sense of self-control. The ego is being developed. If the caregiver is extremely controlling about potty training (stands over the child waiting for the smallest indication that the child might need to go to the potty and immediately scoops the child up and places him on the potty chair, for example), the child may grow up fearing losing control. He may become fixated in this stage or “anally retentive”—fearful of letting go. Such a person might be extremely neat and clean, organized, reliable, and controlling of others. If the caregiver neglects to teach the child to control urges, he may grow up to be “anal expulsive” or an adult who is messy, irresponsible, and disorganized.

Link to Learning: Toilet Training

To the relief of most parents, there is very little evidence to suggest that Freud was right about fixations caused during the anal stage, mainly because the theory itself would be very difficult to test. Nevertheless, parents worry about toilet training, and whether they will be able to guide their children through the process unscathed. Kidshealth.org has a good web page on to potty training  that may help parents worried about toilet training.

We have explored the dramatic story of the first two years of life. Rapid physical growth, neurological development, language acquisition, the movement from hands-on to mental learning, an expanding emotional repertoire, and the initial conceptions of self and others make this period of life very exciting. These abilities are shaped into more sophisticated mental processes, self-concepts, and social relationships during the years of early childhood.

Babies begin to learn about the world around them from a very early age. Children’s early experiences, meaning the bonds they form with their parents and their first learning experiences, affect their future physical, cognitive, emotional, and social development. Various organizations and agencies are dedicated to helping parents (and other caregivers), educators, and health care providers understand the importance of early healthy development. Healthy development means that children of all abilities, including those with special health care needs, are able to grow up where their social, emotional, and educational needs are met. Having a safe and loving home and spending time with family―playing, singing, reading, and talking―are very important. Proper nutrition, exercise, and sleep can also make a big difference; and effective parenting practices are key to supporting healthy development (CDC, 2019). The need to invest in very young children is important to maximize their future well-being.

Additional Supplemental Resources

• Students will interact with the map and chart to review major areas of the brain and their functions. Toggle down on the top left menu to choose different structures to explore.
• Besides tracking your child’s growth and development, you can learn about topics such as developmental disabilities, immunization recommendations, and screening.
• This website brings together existing information and practical strategies on feeding healthy foods and drinks to infants and toddlers, from birth to 24 months of age.
• The website information on infant sleep patterns and habits. Feel free to explore their multiple topics on the subject.
• The Institute for Learning & Brain Sciences (I-LABS) is the world’s leading interdisciplinary research center on early learning and brain development. Our groundbreaking research is revolutionizing our understanding of children’s development in their early years, and revealing how this affects brain changes in adolescence, adulthood, and aging.
• See how developmental psychologists conduct research with young infants. Closed captioning available.
• CNN takes a look inside what might be the most complex biological system in the world: the human brain.
• This video shows that infant rhesus monkeys appear to form an affectional bond with soft, cloth surrogate mothers that offered no food but not with wire surrogate mothers that provided a food source but are less pleasant to touch.
• This video shows the test that American psychologist Mary Ainsworth developed for studying attachment in infants.
• The attachment theory argues that a strong emotional and physical bond to one primary caregiver in our first years of life is critical to our development. This video explains the different styles of attachment.
• This video shows the Piaget test of object permanence.
• How do babies learn so much from so little so quickly? In a fun, experiment-filled talk, cognitive scientist Laura Schulz shows how our young ones make decisions with a surprisingly strong sense of logic, well before they can talk.
• “Babies and young children are like the R&D division of the human species,” says psychologist Alison Gopnik. Her research explores the sophisticated intelligence-gathering and decision-making that babies are really doing when they play.

Learning and Development of Language: The First 5 Years of Life  

• In this video, we’ll look at four things known about Language Learning in general and then listen to the story of lucky Lucy and poor Pete to understand the importance of language in everyday life.

Noam Chomsky on Language Acquisition  

• How is it that we learn to speak and think in language so easily? Philosophers have argued about whether or not we have innate ideas. Whether we are born knowing things, as Plato believed, or rather, as John Locke and other empiricists argued, the mind is a blank slate on which experience writes. Noam Chomsky gave a twist to this debate in the 1960s.

Schemas, assimilation, and accommodation | Khan Academy  

• This video summarizes the concepts of assimilation and accommodation that take place during the sensorimotor stage.
• Heather Lanier’s daughter Fiona has Wolf-Hirschhorn syndrome, a genetic condition that results in developmental delays — but that doesn’t make her tragic, angelic or any of the other stereotypes about kids like her. In this talk about the beautiful, complicated, joyful and hard journey of raising a rare girl, Lanier questions our assumptions about what makes a life “good” or “bad,” challenging us to stop fixating on solutions for whatever we deem not normal, and instead to take life as it comes.

Lifespan Development Copyright © 2020 by Julie Lazzara is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted.

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Casebook: Developmentally Appropriate Practice in Early Childhood Programs Serving Children from Birth Through Age 8

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About the book.

• Make connections to the fourth edition of Developmentally Appropriate Practice in Early Childhood Programs 
• Think critically about the influence of context on educator, child, and family actions 
• Discuss the effectiveness of the teaching practices and how they might be improved 
• Support your responses with evidence from the DAP position statement and book 
• Explore next steps beyond the case details 
• Apply the learning to your own situation 

Table of Contents

• Editors, Contributors, and Reviewers
• Introduction and Book Overview | Jennifer J. Chen and Dana Battaglia
• 1.1 Missed Opportunities: Relationship Building in Inclusive Classrooms | Julia Torquati
• 1.2 “My Name Is Not a Shame” | Kevin McGowan
• 1.3 Fostering Developmentally Appropriate Practice Through Virtual Family Connections | Lea Ann Christenson
• 1.4 Counting Collections in Community | Amy Schmidtke
• 1.5 The Joy Jar: Celebrating Kindness | Leah Schoenberg Muccio
• 1.6 Prioritizing Listening to and Learning from Families | Amy Schmidtke 
• 2.1 Julio’s Village: Early Childhood Education Supports for Teen Parents | Donna Kirkwood
• 2.2 Healthy Boundaries: Listening to Children and Learning from Families | Jovanna Archuleta
• 2.3 Roadmap of Family Engagement to Kindergarten: An Ecological Systems Approach | Marcela Andrés
• 2.4 Taking Trust for Granted? The Importance of Communication and Outreach in Family Partnerships | Suzanna Ewert
• 2.5 Book Reading: Learning About Migration and Our Family Stories | Sarah Rendón García 
• 3.1 Pairing Standardized Scale with Observation | Megan Schumaker-Murphy
• 3.2 The Power of Observing Jordan | Marsha Shigeyo Hawley and Barbara Abel
• 3.3 “But What Is My Child Learning?” | Janet Thompson and Jennifer Gonzalez
• 3.4 Drawing and Dialogue: Using Authentic Assessment to Understand Children’s Sense of Self and Observe Early Literacy Skills | Brandon L. Gilbert
• 3.5 The ABCs of Kindergarten Registration: Assessment, Background, and Collaboration Between Home and School | Bridget Amory
• 3.6 Creating Opportunities for Individualized Assessment Activities for Biliteracy Development | Esther Garza
• 3.7 Observing Second-Graders’ Vocabulary Development | Marie Ann Donovan
• 3.8 Writing Isn’t the Only Way! Multiple Means of Expressing Learning | Lee Ann Jungiv 
• 4.1 Engaging with Families to Individualize Teaching | Marie L. Masterson 
• 4.2 Tumbling Towers with Toddlers: Intention and Decision Making Over Blocks | Ron Grady  
• 4.3 What My Heart Holds: Exploring Identity with Preschool Learners | Cierra Kaler-Jones 
• 4.4 “I See a Really Big Gecko!” When Background Knowledge and Teaching Materials Don’t Match | Germaine Kaleilehua Tauati and Colleen E. Whittingham 
• 4.5 Using a Humanizing and Restorative Approach for Young Children to Develop Responsibility and Self-Regulation | Saili S. Kulkarni, Sunyoung Kim, and Nicola Holdman 
• 4.6 Joyful, Developmentally Appropriate Learning Environments for African American Youth | Lauren C. Mims, Addison Duane, LaKenya Johnson, and Erika Bocknek 
• 5.1 Using the Environment and Materials as Curriculum for Promoting Infants’ and Toddlers’ Exploration of Basic Cause-and-Effect Principles | Guadalupe Rivas 
• 5.2 Social Play Connections Among a Small Group of Preschoolers | Leah Catching 
• 5.3 Can Preschoolers Code? A Sneak Peek into a Developmentally Appropriate Coding Lesson | Olabisi Adesuyi-Fasuyi 
• 5.4 Everyday Gifts: Children Show Us the Path—We Observe and Scaffold | Martha Melgoza 
• 5.5 Learning to Conquer the Slide Through Persistence and Engaging in Social Interaction | Sueli Nunes 
• 5.6 “Sabes que todos los caracoles pueden tener bebés? Do You Know that All Snails Can Have Babies?” Supporting Children’s Emerging Interests in a Dual Language Preschool Classroom | Isauro M. Escamilla 
• 5.7 “Can We Read this One?” A Conversation About Book Selection in Kindergarten | Larissa Hsia-Wong  
• 6.1 Take a Chance on Coaching: It’s Worth It! | Lauren Bond 
• 6.2 It Started with a Friendship Parade | Angela Vargas 
• 6.3 The World Outside of the Classroom: Letting Your Voice Be Heard | Meghann Hickey 
• 7.1 Communication as a Two-Way Street? Creating Opportunities for Engagement During Meaningful Language Routines | Kameron C. Cardenv 
• 7.2 Eli Goes to Preschool: Inclusion for a Child with Autism Spectrum Disorder | Abby Hodges
• 7.3 Preschool Classroom Supports and Embedded Interventions with Coteaching | Racheal Kuperus and Desarae Orgo
• 7.4 Addressing Challenging Behavior Using the Pyramid Model | Ellie Bold
• 7.5 Dual Language or Disability? How Teachers Can Be the First to Help | Alyssa Brillante
• 7.6 Adapting and Modifying Instruction Using Reader’s Theater | Michelle Gonzalez
• 7.7 Supporting Children with Learning Disabilities in Mathematics: The Importance of Observation, Content Knowledge, and Context | Renee B. Whelan 
• 8.1 Facilitating a Child’s Transition from Home to Group Care Through the Use of Cultural Caring Routines | Josephine Ahmadein
• 8.2 Engaging Dual Language Learners in Conversation to Support Translanguaging During a Small Group Activity | Valeria Erdosi and Jennifer J. Chen
• 8.3 Incorporating Children’s Cultures and Languages in Learning Activities | Eleni Zgourou
• 8.4 Adapting Teaching Materials for Dual Language Learners to Reflect Their Home Languages and Cultures in a Math Lesson | Karen Nemeth
• 8.5 Studying Celestial Bodies: Science and Cultural Stories | Zeynep Isik-Ercan
• 8.6 Respecting Diverse Cultures and Languages by Sharing and Learning About Cultural Poems, Songs, and Stories From Others | Janis Strasser

Book Details

Faculty resources.

To access tips and resources for teaching the cases, please complete this brief form.  You’ll be able to download the items after you complete the form. 

Teacher Inquiry Group Resources

To access reflection questions to deepen your learning, please click here.

More DAP Resources

To read the position statement, access related resources, and stay up-to-the-minute on all things DAP, visit  NAEYC.org/resources/developmentally-appropriate-practice .

Pamela Brillante,  EdD, is professor in the Department of Special Education, Professional Counseling and Disability Studies, at William Paterson University. She has worked as an early childhood special educator, administrator, and New Jersey state specialist in early childhood special education. She is the author of the NAEYC book The Essentials: Supporting Young Children with Disabilities in the Classroom. Dr. Brillante continues to work with schools to develop high-quality inclusive early childhood programs. 

Jennifer J. Chen, EdD, is professor of early childhood and family studies at Kean University. She earned her doctorate from Harvard University. She has authored or coauthored more than 60 publications in early childhood education. Dr. Chen has received several awards, including the 2020 NAECTE Foundation Established Career Award for Research on ECTE, the 2021 Kean Presidential Excellence Award for Distinguished Scholarship, and the 2022 NJAECTE’s Distinguished Scholarship in ECTE/ECE Award. 

Stephany Cuevas, EdD, is assistant professor of education in the Attallah College of Educational Studies at Chapman University. Dr. Cuevas is an interdisciplinary education scholar whose research focuses on family engagement, Latinx families, and the postsecondary trajectories of first-generation students. She is the author of Apoyo Sacrifical, Sacrificial Support: How Undocumented Parents Get Their Children to College (Teachers College Press). 

Christyn Dundorf, PhD, has more than 30 years of experience in the early learning field as a teacher, administrator, and adult educator. She serves as codirector of Teaching Preschool Partners, a nonprofit organization working to grow playful learning and inquiry practices in school-based pre-K programs and infuse those practices up into the early grades.

Emily Brown Hoffman, PhD, is assistant professor in early childhood education at National Louis University in Chicago. She received her PhD from the University of Illinois at Chicago in Curriculum & Instruction, Literacy, Language, & Culture. Her focuses include emergent literacy, leadership, play and creativity, and school, family, and community partnerships. 

Daniel R. Meier, PhD, is professor of elementary education at San Francisco State University. His publications include Critical Issues in Infant-Toddler Language Development: Connecting Theory to Practice (editor), Supporting Literacies for Children of Color: A Strength-Based Approach to Preschool Literacy (author), and Learning Stories and Teacher Inquiry Groups: Reimagining Teaching and Assessment in Early Childhood Education (coauthor). 

Gayle Mindes, EdD, is professor emerita, DePaul University. She is the author of Assessing Young Children , fifth edition (with Lee Ann Jung), and Social Studies for Young Children: Preschool and Primary Curriculum Anchor, third edition (with Mark Newman). Dr. Mindes is also the editor of Teaching Young Children with Challenging Behaviors: Practical Strategies for Early Childhood Educators and Contemporary Challenges in Teaching Young Children: Meeting the Needs of All Students . 

Lisa R. Roy, EdD, is executive director for the Colorado Department of Early Childhood. Dr. Roy has supported families with young children for over 30 years, serving as the director of program development for the Buffett Early Childhood Institute, as the executive director of early childhood education for Denver Public Schools, and in various nonprofit and government roles.

Chapter 4: Infancy

Learning Objectives

At the end of this chapter, you will be able to:

• Summarize overall physical growth during infancy
• Describe the development of the brain during infancy
• Contrast the development of the senses in newborns
• Compare gross and fine motor skills and give examples of each
• Explain the merits of breastfeeding
• Discuss the nutritional concerns of Marasmus and Kwashiorkor
• List and describe the six substages of sensorimotor intelligence
• Describe stages of language development during infancy
• Define babbling, holophrastic speech, and overregularization
• Contrast styles of attachment
• Discuss the importance of temperament and goodness of fit
• Describe self-awareness, stranger wariness, and separation anxiety
• Use Erikson’s theory to characterize psychosocial development during infancy

Louisiana Snapshot

Breastfeeding is widely recommended for newborn infants as it provides numerous health benefits. However, certain factors such as pre-existing conditions, medication intake by the mother, congenital disabilities, or adoption can make it challenging for some mothers to breastfeed their babies. Despite these challenges, the American Academy of Pediatrics still recommends breastfeeding or providing human milk to infants. Unfortunately, some mothers, particularly those of color, face additional barriers, such as a lack of supportive workplace policies, cultural obstacles, and limited access to financial and educational resources.

To address these inequities, a local non-profit organization called “I Am New Orleans” has taken the initiative to support mothers in the city. They provide a community of practice, lactation consultants, and equipment to help mothers breastfeed their babies. This support helps mothers overcome barriers and provides babies with increased immunity, better nutrition, and longer-term cognitive development.

Introduction

Welcome to the story of development from infancy through toddlerhood, from birth until about two years of age. Researchers have given this part of the lifespanmore attention than any other period, perhaps because changes during this time are so dramatic and so noticeable and probably because we have assumed that what happens during these years provides a foundation for one’s life to come. However, it has been argued that the significance of development during these years has been overstated (Bruer, 1999). Nevertheless, contemporary educators, healthcare providers, and parents have focused on this period of life most heavily. We will examine growth and nutrition during infancy cognitive development during the first two years and then turn our attention toward attachments formed in infancy.

Physical Development

Overall physical growth.

The average weight of a newborn in the United States is around 7.5 pounds, with a length of about 20 inches. During the first few days of life, infants can lose up to 5% of their body weight due to waste elimination and adjusting to feeding. Although most parents may not notice this, it can be a concern for those with smaller infants. However, this weight loss is temporary and followed by a rapid growth period. Usually, infants double their birth weight by reaching four months and triple their birth weight by their first year. By the age of two, their weight quadruples. On average, infants are about 26-32 inches long by their first birthday.

Body Proportions

Our body goes through many physical changes during the first few years of life, and one of the most significant changes is in our body proportions. When we are in the womb, our head accounts for about 50 percent of our entire length, but at birth, it accounts for only around 25 percent. By age 25, it makes up about 20 percent of our length. If you think about it, you can imagine how challenging it must be for an infant to raise their head during the first year of life. If you have ever seen a 2-to-4-month-old baby lying on their stomach, trying to lift their head, you will know how difficult this can be.

The Brain in the First Two Years

The brain undergoes significant physical changes during the early years of a child’s life. At birth, the brain is only about 25 percent of its adult weight, which is relatively small compared to other organs in the body. However, by age two, it has grown to 75 percent of its adult weight; by age six, it has reached 95 percent. The brain gets its full adult size by the age of seven years.

Although most of the brain’s neurons are present at birth, they are not fully developed. During the next few years, the dendrites, which are the connections between neurons, undergo a period of temporary dramatic growth called transient exuberance. This dramatic increase in dendrites occurs primarily during the first two years of life, resulting in thousands of dendrites for a single neuron by age two. After this period of growth, the neural pathways that are not used will be eliminated, making the ones that are used much stronger. This process primarily occurs in the cortex, the thin outer covering of the brain responsible for voluntary activity and thinking. The prefrontal cortex, located behind the forehead and responsible for regulating emotions, planning activities, strategizing, and judgment, continues to grow and mature throughout childhood and undergoes an additional growth spurt during adolescence. It is the last part of the brain to develop, accounting for 85 percent of the brain’s weight. The connections that are maintained and lost are shaped by experiences. Eventually, 40 percent of these connections will be lost.

Another significant change in the central nervous system is the development of myelin, a coating of fatty tissues around the neuron’s axon. This insulation helps speed up the transmission of impulses from one cell to another, improving the building of neural pathways and coordination and control of movement and thought processes. The development of myelin continues into adolescence but is most dramatic during the first several years of life.

This video provides an introduction to how the growth of the brain translates into cognitive abilities in infants.

From Reflexes to Voluntary Movements

Babies develop essential motor skills and movement abilities during the first two years of life. The process begins with developing reflexes, which are involuntary movements in response to different types of stimulation. Some of these reflexes are necessary for survival, such as the breathing reflex, which includes hiccups, sneezing, and thrashing. Other reflexes help maintain body temperature, including crying, shivering, tucking the legs close, and pushing away blankets. The sucking reflex is another important one that allows babies to feed by automatically sucking on any object that touches their lips. Additionally, the rooting reflex helps babies search for a nipple by turning toward any object that touches their cheek.

While some reflexes are essential for survival, others signal the state of brain and body functions. For example, the Babinski reflex makes toes fan upward when feet are stroked, the stepping reflex makes babies move their legs as if to walk when feet touch a flat surface, the palmar grasp makes the infant tightly grasp any object placed in its palm, and the Moro reflex makes babies fling their arms out and then bring them to the chest if they hear a loud noise. These movements occur automatically and sign that the infant is neurologically functioning well.

Within the first few weeks of life, the reflexes are gradually replaced by voluntary movements or motor skills, which are essential for a baby’s growth and development.

Gross Motor Skills

Gross motor skills refer to voluntary movements involving large muscle groups like the arms, legs, head, and torso. These skills are the first to develop, and examples include lifting the head while lying on the stomach, moving the chest up and down, and rocking back and forth on hands and knees. Additionally, this category of skills also encompasses exploring objects with one’s feet, which many babies do as early as eight weeks of age, especially if seated in a carrier or other device that frees the hips. This may be easier for babies than reaching for objects with their hands, which requires more practice (Berk, 2007). Interestingly, sometimes infants who try to crawl towards an object may move backward due to the greater strength in their arms compared to their legs!

Fine Motor Skills

Developing fine motor skills involves precise hand and finger movements, such as reaching and grasping objects. Initially, newborns cannot grasp objects intentionally, although they wave their arms toward something that catches their attention. At around four months, infants reach for an object, first with both arms and then with one arm. They use their fingers and palms but not thumbs to grasp objects. You can try it yourself. How much control do you have over the object? If you are using a pen or pencil, can you write or draw with it? You may find it challenging to perform these tasks because the thumb is crucial for a pincer grasp, which babies develop around nine months. This new skill significantly improves their ability to control and manipulate objects and brings them great pleasure. By the age of nine months, infants can track a moving object, reach for it, and grasp it, which is a complex set of actions, considering these skills were not present just a few months earlier.

Sensory Development

The womb is a dark and visually unstimulating environment, meaning newborns have a poorly developed sense of vision at birth. They typically cannot see beyond 8 to 16 inches from their faces, struggle to keep moving objects in their gaze, and are better at detecting contrast than color differences. It takes a lot of cognitive effort for newborns to take in visual stimulation and build neural pathways between their eyes and brains.

When we look at someone, we usually look into their eyes. But newborns don’t scan objects this way. Instead, they focus on less detailed parts of the face, such as the chin. However, by 2 or 3 months of age, they begin to seek out more detailed visual stimulation and show preferences for unusual images over familiar ones, patterns over solids, faces over patterns, and three-dimensional objects over flat photos.

Newborns also have difficulty distinguishing colors, but within a few months, they can discriminate between colors just like adults. They also develop the ability to perceive depth as binocular vision develops at around two months old. By six months, they can even perceive depth in pictures. Infants with crawling and exploration experience tend to pay greater attention to visual cues of depth and modify their actions accordingly.

At birth, babies have a keen sense of hearing. This ability to hear develops around the fifth month of prenatal development. Babies can differentiate between similar sounds as early as one month after birth and recognize familiar voices even earlier. As they become more familiar with the sounds of their native language, their sensitivity to sounds that are part of an unfamiliar language decreases. By around 7-8 months, some of this ability to distinguish between sounds may be lost.

This video demonstrates an infant’s sense of hearing and vision at birth and shortly after.

Other Senses

Pain and touch.

After babies are born, they are sensitive to touch and temperature and can feel pain, manifested through crying and changes in their cardiovascular system. Touch is a critical sense for infants, and it plays an essential role in their physical development, language, cognitive skills, and socio-emotional competency. Touch is crucial in the short term and has long-term effects, highlighting the significance of upbeat, gentle touch from birth. Babies explore and learn about their environment through touch, form bonds with their caregivers, and communicate their needs and desires. Research has shown the significant benefits of touch for premature babies, but all children can benefit from such contact (Stack, D. M., 2010).

Taste and Smell

Newborns are incredibly receptive to their surroundings and can distinguish between different flavors, such as sour, bitter, sweet, and salty. They tend to prefer sweet tastes. Additionally, they can differentiate between their mother’s scent and that of others, and they find the smell of their mother to be pleasant. A newborn placed on the mother’s chest will instinctively inch up towards the mother’s breast, as it is a potent source of maternal odor. Infants, even on the first day of life, orient themselves to their mother’s scent and are soothed by it when they cry (Sullivan et al., 2011).

Breast milk is considered the ideal diet for newborns. It has the right amount of calories, fat, and protein to support overall physical and neurological development; it provides a source of iron more easily absorbed in the body than the iron found in dietary supplements; it provides resistance against many diseases; infants more easily digest it than formula; and it helps babies make a transition to solid foods more quickly than if bottle-fed. For all of these reasons, it is recommended that mothers breastfeed their infants until at least six months of age and that breast milk be used in the diet throughout the first year (U.S. Department of Health and Human Services, 2004a in Berk, 2007).

However, most mothers who breastfeed in the United States stop breastfeeding at about 6-8 weeks, often to return to work outside the home. Mothers can continue to provide breast milk to their babies by expressing and freezing the milk to be bottle-fed later or by being available to their infants at feeding time. Still, some mothers find that after the initial encouragement they receive in the hospital to breastfeed, the outside world is less supportive of such efforts. Some workplaces support breastfeeding mothers by providing flexible schedules and welcoming infants, but many do not. And the public support of breastfeeding is sometimes lacking. Women in Canada are more likely to breastfeed than those in the United States, and the Canadian health recommendation is for breastfeeding to continue until two years of age. Facilities in public places in Canada, such as malls, ferries, and workplaces, provide more support and comfort for breastfeeding mothers and children than in the United States.

One early argument given to promote the practice of breastfeeding was that it promoted bonding and healthy emotional development for infants. However, this does not seem to be the case. Breastfed and bottle-fed infants adjust equally well emotionally (Ferguson and Woodward, 1999). This is good news for mothers who may be unable to breastfeed for a variety of reasons and for fathers who might feel left out as a result.

In addition to the nutritional benefits of breastfeeding, breast milk is free! Anyone who has priced formula recently can appreciate this added incentive to breastfeeding. Prices for a month’s worth of formula can easily range from $130-200. Breastfeeding also stimulates uterine contractions to help it regain its standard size. And women who breastfeed are more likely to space their pregnancies further apart.

A Historic Look at Breastfeeding

The use of wet nurses, who were lactating women hired to nurse others’ infants, declined during the Middle Ages. Mothers began breastfeeding their infants more frequently in the late 1800s. However, in the early 20th century, breastfeeding began to decrease again. By the 1950s, middle-class and affluent mothers practiced breastfeeding less frequently as formula became superior to breast milk. In the late 1960s and 1970s, there was a renewed emphasis on natural childbirth and breastfeeding, and the benefits of breastfeeding were more widely publicized. Gradually, breastfeeding rates began to climb, especially among middle-class and educated mothers who received the most vital breastfeeding messages. Today, lactation specialists consult with women before they leave the hospital to ensure they are aware of breastfeeding benefits, receive support and encouragement, and get their infants used to taking the breast. It may not happen immediately; first-time mothers can become upset or discouraged. In such cases, lactation specialists and nursing staff can encourage the mother to keep trying until the baby and mother are comfortable feeding.

Global Considerations and Malnutrition

In the 1960s, formula companies led campaigns in developing countries to encourage mothers to feed their babies on infant formula. Many mothers felt that formula would be superior to breast milk and began using formula. The formula can be used safely with adequate, clean water to mix it and the proper means to sanitize bottles and nipples. However, in many of these countries, such conditions were not available, and babies often were given diluted, contaminated formula, which made them become sick with diarrhea and become dehydrated. Breastfeeding rates declined in Peru from 90 percent to 10 percent in just eight years (Berger, 2001). These conditions continue today, and now many hospitals prohibit the distribution of formula samples to new mothers to get them to rely on breastfeeding. Many of these mothers do not understand the benefits of breastfeeding and have to be encouraged and supported to promote this practice. Breastfeeding could save the lives of millions of infants each year, according to the World Health Organization, yet fewer than 40 percent of infants are breastfed exclusively for the first six months of life. Find out more at the WHO’s ten facts on breastfeeding . Most women can breastfeed unless they are receiving chemotherapy or radiation therapy, have HIV, are dependent on illicit drugs, or have active, untreated tuberculosis.

Children in developing countries and countries experiencing the harsh conditions of war are at risk for two major types of malnutrition. Infantile marasmus refers to starvation due to a lack of calories and protein. Children who do not receive adequate nutrition lose fat and muscle until their bodies can no longer function. Babies who are breastfed are much less at risk of malnutrition than those who are bottle-fed. After weaning, children who have diets deficient in protein may experience kwashiorkor, or the “disease of the displaced child,” often occurring after another child has been born and taken over breastfeeding. This results in a loss of appetite and swelling of the abdomen as the body begins to break down the vital organs as a source of protein.

The Breast Milk Industry

The benefits of breast milk are well-known and publicized. The collection and distribution of breast milk has become a million-dollar industry supplying hospitals and others in need of the ideal diet. For more information, go to ProLacta to see a current development in the story of breast milk.

Milk Anemia in the United States

About 9 million children in the United States are malnourished (Children’s Welfare, 1998). More still suffer from milk anemia, a condition in which milk consumption leads to a lack of iron in the diet. This can be due to giving toddlers milk as a pacifier when resting, riding, waking, etc. Appetite declines somewhat during toddlerhood, and a small amount of milk (especially with added chocolate syrup) can quickly satisfy a child’s appetite for many hours. The calcium in milk also interferes with iron absorption in the diet. Many preschools and daycare centers give toddlers a drink after meals to prevent spoiling their appetites.

Infant Sleep

Infants 0 to 2 years of age sleep an average of 12.8 hours a day, although this changes and develops gradually throughout an infant’s life. For the first three months, newborns sleep between 14 and 17 hours a day; then, they become increasingly alert for more extended periods. About one-half of an infant’s sleep is rapid eye movement (REM) sleep, and infants often begin their sleep cycle with REM rather than non-REM sleep. They also move through the sleep cycle more quickly than adults. At around six months, babies typically sleep 14-15 hours daily, with 3-4 hours during daytime naps. As they age, these naps decrease from several to typically two naps a day between ages 9-18 months. Often, periods of rapid weight gain or changes in developmental abilities such as crawling or walking will also cause changes to sleep habits.

Cognitive Development

Piaget and sensorimotor intelligence.

Jean Piaget (1896–1980) is one of the most influential cognitive theorists in development. He was inspired to explore children’s ability to think and reason by watching his own children’s development. Piaget describes intelligence in infancy as sensorimotor or based on direct, physical contact. Infants taste, feel, pound, push, hear, and move to experience the world. Let’s examine infants’ transition from responding to the external world reflexively as newborns to solving problems using mental strategies as two-year-olds. Piaget called this first stage of cognitive development sensorimotor intelligence (the sensorimotor period) because infants learn through their senses and motor skills. He subdivided this period into six substages:

Stage One : Reflexive Action (Birth through 1st month) – This active learning begins with automatic movements or reflexes. A bottle comes into contact with an infant’s cheek and is automatically sucked on and licked. But this also happens with sour lemon, much to the infant’s surprise!

Stage Two : First Adaptations to the Environment (1st through 4th months) – Fortunately, within a few days or weeks, the infant begins to discriminate between objects and adjust responses accordingly as reflexes are replaced with voluntary movements. An infant may accidentally engage in a behavior and find it interesting, such as making a vocalization. This interest motivates trying to do it again and helps the infant learn a new behavior that initially occurred by chance. At first, most actions have to do with the body, but in months, they will be directed more toward objects.

Stage Three : Repetition (4th through 8th months) – During the next few months, the infant becomes more and more actively engaged in the outside world and takes delight in being able to make things happen. Repeated motion brings particular interest as the infant can bang two lids together from the cupboard when seated on the kitchen floor.

Stage Four: New Adaptations and Goal-Directed Behavior (8th through 12th months) – Now, the infant can engage in behaviors that others perform and anticipate upcoming events. Perhaps because of continued maturation of the prefrontal cortex, the infant becomes capable of thinking and carrying out a planned, goal-directed activity, such as seeking a toy that has rolled under the couch. The object continues to exist in the infant’s mind even when out of sight, and the infant can now attempt to retrieve it. This is an example of a lack of object permanence.

Was Piaget right? Dr. Rene Baillargeon explains in this clip how infants recognize that objects have permanence at much younger ages, even as young as 3.5 months old.

Stage Five: Active Experimentation of Little Scientists (12th through 18th months) – Infants from one year to 18 months more actively experiment to learn about the physical world. Gravity is comprehended by pouring water from a cup or pushing bowls from highchairs. The caregiver tries to help the child by picking it up again and placing it on the tray. And what happens? Another experiment! The child pushes it off the tray again, causing it to fall, and the caregiver picks it up again! A closer examination of this stage causes us to appreciate how much learning is going on and how many things we take for granted must be learned. I remember handing my daughters (who are close in age) a small container of candy when they were both seated in the car’s back seat. They struggled to move the pieces up and out of the small box and became frustrated when their fingers would lose their grip on the treats before they made it up and out of the top of the boxes. They had not yet learned to use gravity and turn the box over in their hands! This is a beautiful and messy time of experimentation, and most learning occurs by trial and error.

Stage Six: Mental Representations (18th month to 2 years of age) – The child is now able to solve problems using mental strategies, to remember something heard days before and repeat it, to engage in pretend play, and to find objects that have been moved even when out of sight. Take, for instance, the child upstairs in a room with the door closed, supposedly taking a nap. The doorknob has a safety device that makes it impossible for the child to turn the knob. After trying several times in vain to push the door or turn the doorknob, the child carries out a mental strategy to get the door opened and knocks on the door! This is a technique learned from the experience of hearing a knock on the door and observing someone opening the door. The child is now better equipped with mental strategies for problem-solving. This initial movement from the “hands-on” approach to knowing about the world to the more mental world of stage six marked the transition to preoperational intelligence that we will discuss in the next lesson. Part of this stage involves learning to use language.

Language Development

Newborn Communication

Do newborns communicate? Indeed, they do. They do not, however, communicate with the use of language. Instead, they share their thoughts and needs with body posture (relaxed or still), gestures, cries, and facial expressions. A person who spends adequate time with an infant can learn which cries indicate pain and which indicate hunger, discomfort, or frustration.

Intentional vocalizations:   Cooing and taking turns: Infants begin to vocalize and repeat vocalizations within the first few months of life. That gurgling, musical vocalization called cooing can serve as a source of entertainment for an infant laid down for a nap or seated in a carrier on a car ride. Cooing serves as practice for vocalization, and the infant hears the sound of their voice and tries to repeat entertaining sounds. Infants also begin to learn the pace and pause of conversation as they alternate their vocalization with someone else and then turn again when the other person’s vocalization has stopped. Cooing initially involves making vowel sounds like “oooo.” Later, consonants are added to vocalizations, such as “nana nana nana.”

Babbling and gesturing :  At about four to six months, infants begin making even more elaborate vocalizations , including the sounds required for any language. Guttural sounds, clicks, consonants, and vowel sounds stand ready to equip the child with the ability to repeat whatever sounds are characteristic of the speech heard. Eventually, these sounds will no longer be used as the infant grows more accustomed to a particular language. Deaf babies also use gestures to communicate wants, reactions, and feelings. Because gesturing seems easier than vocalization for some toddlers, sign language is sometimes taught to enhance one’s ability to communicate by using the ease of gesturing. The rhythm and speech pattern is used when deaf babies sign, just as when hearing babies babble.

Understanding: At around ten months, the infant can understand more than they can say. You may have also experienced this phenomenon if you have tried to learn a second language. You may have been able to follow a conversation more easily than to contribute to it.

Holophrastic speech: Children begin using their first words at about 12 or 13 months of age and may use partial words to convey thoughts at even younger ages. These one-word expressions are referred to as holophrastic speech. For example, the child may say “ju” for the word “juice” and use this sound when referring to a bottle. The listener must interpret the meaning of the holophrase, and interpretation is not too difficult when this is someone who has spent time with the child. They know that “ju” means “juice,” which means the baby wants milk! But someone who has not been around the child will have trouble understanding what is intended. Imagine the parent who, to a friend, exclaims, “Ezra’s talking all the time now!” The friend hears only “ju da ga,” which, the parent explains, means “I want some milk when I go with Daddy.”

Under-extension: A child who learns that a word stands for an object may initially think that the word can be used for only that particular object. Only the family’s Irish Setter is a “doggie.” This is referred to as under-extension. More often, however, a child may think that a label applies to all objects similar to the original. In overextension, all animals become “doggies,” for example.

First words and cultural influences: The first words tend to be nouns if the child uses English . The child labels objects such as cups or balls. However, children may learn more verbs in a verb-friendly language like Chinese. This may also be due to the different emphasis on objects based on culture. Chinese children may be taught to notice actions and relationships between objects. In contrast, children from the United States may be introduced to name an object and its qualities (color, texture, size, etc.). These differences can be seen when comparing interpretations of art by older students from China and the United States.

Vocabulary growth spurt: One-year-olds typically have a vocabulary of about 50 words. But by the time they become toddlers, they have a language of about 200 words and begin putting those words together in telegraphic speech (I think of it now as “text message” speech because texting is more common and is similar in that text messages typically only include the minimal amount of words to convey the message).

Two-word sentences and telegraphic (text message?) speech: Words are soon combined, and 18-month-old toddlers can express themselves further by using expressions such as “baby bye-bye” or “doggie pretty.” Words needed to convey messages are used, but the articles and other parts of speech necessary for grammatical correctness are not yet used. These expressions sound like a telegraph (or perhaps a better analogy today would be that they read like a text message) where unnecessary words are not used. “Give baby ball” is used rather than “Give the baby the ball.” Or a “Send money now!” text message rather than “Dear Mother. I need some money to take care of my expenses.” You get the idea.

Child-directed speech:  Why is a horse a “horsie”? Have you ever wondered why adults use “baby talk” or sing-song intonation and exaggeration when talking to children? This represents a universal tendency known as child-directed speech, motherese, or parentese . It involves exaggerating the vowel and consonant sounds, using a high-pitched voice, and delivering the phrase with great facial expressions. Why is this done? It may be to clearly articulate the sounds of a word so that the child can hear the sounds involved. Or it may be because when this type of speech is used, the infant pays more attention to the speaker, which sets up a pattern of interaction in which the speaker and listener are in tune with one another. When I demonstrate this in class, the students pay attention and look my way. Amazing! It also works in the college classroom!

Listen to Learn

Parentese occurs across languages and cultures.

Listen to  The science is in: Everyone recognizes and uses baby talk with infants for some examples of parentese in English, Mandarin, Hadza, and Nyang’atom.

Theories of Language Development

The first two theories of language development represent two extremes in the level of interaction required for language to occur (Berk, 2007).

Noam Chomsky and the language acquisition device: The view known as nativism advocated by Noam Chomsky suggests that infants are equipped with a neurological construct called the language acquisition device or LAD that prepares infants for language. Language develops as long as the infant is exposed to it. No teaching, training, or reinforcement is required for language to develop.

B. F. Skinner and reinforcement: Learning theorist B. F. Skinner suggests that language develops through reinforcement. Sounds, words, gestures, and phrases are encouraged by following the behavior with words of praise or treats or anything that increases the likelihood that the behavior will be repeated.

Social pragmatics: Another view emphasizes the child’s active engagement in learning a language out of a need to communicate. The child seeks information, memorizes terms, imitates the speech heard from others, and learns to conceptualize using words as language is acquired. Many would argue that all three of these dynamics foster the acquisition of language (Berger, 2004).

Psychosocial Development and Attachment

Emotional development.

At birth, infants exhibit two emotional responses: attraction and withdrawal. They show attraction to pleasant situations that bring comfort, stimulation, and pleasure. And they withdraw from unpleasant stimulation such as bitter flavors or physical discomfort. At around two months, infants exhibit social engagement in the form of social smiling as they respond with smiles to those who engage their favorable attention. Pleasure is expressed as laughter at 3 to 5 months of age, and displeasure becomes more specific as fear, sadness, or anger between ages 6 and 8 months. This fear is often associated with the presence of strangers or the departure of significant others, known respectively as stranger wariness and separation anxiety, which appear sometime between 6 and 15 months. Some indications indicate that infants may experience jealousy as young as six months (Hart & Carrington, 2002).

During the second year of life, children begin to recognize themselves as they gain a sense of self as an object. This is illustrated in the 15-month-old child’s ability to recognize one’s reflection in a mirror. (The classic mirror or rouge test involves showing a toddler a mirror after secretly rubbing red coloring on the child’s nose. Children younger than 15 months may try to wipe the color from the mirror. But a 15-month-old child may wipe the color from their nose.) Once a child has self-awareness, the child moves toward understanding social emotions such as guilt, shame, embarrassment, sympathy, or empathy. These will require an understanding of the mental state of others that is acquired at around age 3 to 5 and will be explored in our next lesson (Berk, 2007).

Forming Attachments

The significance of early attachments:  An attachment is a desire for physical closeness with someone. The formation of attachments in infancy has been the subject of considerable research as attachments have been viewed as foundations for future relationships, as the basis for confidence and curiosity as toddlers, and as essential influences on self-concept.

Measuring attachment styles: The classic model for studying attachment styles involves having a caregiver and child come into a strange room filled with toys and observing the child’s reactions. A securely attached child will play with the toys and bring one to the caregiver to show and describe occasionally. The child is content and secure as they explore the situation. An insecurely resistant child will cling to the caregiver and refuse to go and play. An insecure-avoidant attachment style is indicated by a child who is neither curious nor clingy; instead, the child sits and waits until it is time to go.

Attachment styles vary in the amount of security and closeness felt in the relationship, and they can change with new experiences.   The type of attachment fostered in parenting styles varies by culture as well. For example, German parents value independence, and Japanese mothers are typically by their children’s sides. As a result, the rate of insecure-avoidant attachments is higher in Germany, and insecure-resistant attachments are more elevated in Japan. However, these differences reflect cultural variation rather than insecurity (van Ijzendoorn and Sagi, 1999). Keep in mind that methods for measuring attachment styles have been based on a model that reflects middle-class, U.S. values and interpretation. Newer methods for assessing attachment styles involve using a Q-sort technique in which many behaviors are recorded on cards, and the observer sorts the cards in a way that reflects the type of behavior that occurs within the situation.

As we explore attachment styles below, consider how these are evidenced in adult relationships.

Types of Attachments

Secure:  A secure attachment is one in which the child feels confident that needs will be met promptly and consistently. In North America, this interaction may include emotional connection and adequate care. However, secure attachments can develop in cultures where mothers do not talk, cuddle, and play with their infants (LeVine et al., 1994). Secure attachments can form provided the child has consistent contact and care from one or more caregivers. Consistency of contacts may be jeopardized if the infant is cared for in a daycare with a high turnover of caregivers or if institutionalized and given little more than primary physical care. And while infants who, perhaps because of being in orphanages with inadequate care, have not had the opportunity to attach in infancy can form initial secure attachments several years later, they may have more emotional problems of depression or anger or be overly friendly as they make adjustments (O’Connor et al., 2003).

Insecure-Resistant: This attachment style is marked by insecurity and resistance to engaging in activities or playing away from the caregiver. It is as if the child fears the caregiver will abandon them and clings accordingly. (Remember that clingy behavior can also be part of a child’s natural disposition or temperament and does not necessarily reflect some parental neglect.) The child may cry if separated from the caregiver and also cry upon their return. They seek constant reassurance that never seems to satisfy their doubt. This type of insecure attachment might result from not meeting needs consistently or timely.

Consequently, the infant is never sure that the world is trustworthy or that they can rely on others without some anxiety. An unavailable caregiver, perhaps because of marital tension, substance abuse, or preoccupation with work, may send a message to the infant they cannot rely on having needs met. A caregiver who attends to a child’s frustration can help teach them to be calm and to relax. However, an infant who receives only sporadic attention when experiencing discomfort may not learn how to calm down.

Insecure-Avoidant:  This, too, is an attachment style marked by insecurity. But this style is also characterized by a tendency to avoid contact with the caregiver and others. This child may have learned that needs typically go unmet and understands that the caregiver does not provide care and cannot be relied upon for comfort, even sporadically. An insecure-avoidant child learns to be more independent and disengaged. Such a child might sit passively in a toy room until it is time to go.

Disorganized: This represents the most insecure attachment style and occurs when the child is given mixed, confused, and inappropriate responses from the caregiver. For example, a mother who has schizophrenia may laugh when a child is hurting or cry when a child exhibits joy. The child does not learn to interpret emotions or connect with the unpredictable caregiver.

How common are the attachment styles among children in the United States? It is estimated that about 65 percent of children in the United States are securely attached. Twenty percent exhibit avoidant styles, and 10 to 15 percent are resistant. Another 5 to 10 percent may be characterized as disorganized. How would this compare with adults in the United States? (We will look at this in our lesson on early adulthood.)

Temperament

Perhaps you have spent time with some infants. How were they alike? How did they differ? Or compare yourself with your siblings or other children you know well. You may have noticed that some seemed in a better mood than others, were more sensitive to noise, or were more easily distracted than others. These differences may be attributed to temperament. Temperament is an inborn quality noticeable soon after birth. According to Chess and Thomas (1996), children vary on six temperament dimensions. These include activity level, regularity (or predictability), sensitivity thresholds, mood, persistence, or distractibility. The New York Longitudinal Study was a long-term study of infants on these dimensions, which began in the 1950s. Most children do not have their temperament clinically measured, but temperament categories have been developed to help understand and work with children. These categories include easy or flexible, slow to warm up or cautious, complex or aggressive, and undifferentiated (or those who can’t easily be categorized).

Think about how you might approach each type of child to improve your interactions. An easy or flexible child will not need much extra attention unless you want to find out whether they are having difficulties that have gone unmentioned. A slow-to-warm-up child may need to be warned if new people or situations are introduced. A difficult or feisty child may need extra time to burn off their energy. A caregiver’s ability to work well and accurately read the child will enjoy goodness of fit, meaning their styles match, and communication and interaction can flow. Rather than believing that discipline alone will improve children’s behavior, our knowledge of temperament may help a parent, teacher, or other gain insight to work more effectively with a child.

Temperament doesn’t change dramatically as we grow up, but we may learn how to work around and manage our temperamental qualities. Temperament may be one of the things about us that stays the same throughout development.

Psychosocial Development

Erikson’s stages for infants and toddlers.

Trust vs. mistrust : Erikson maintained that the first year and a half of life involve establishing trust. Infants are dependent and must rely on others to meet their basic physical needs as well as their needs for stimulation and comfort. A caregiver who consistently meets these needs instills a sense of trust or the belief that the world is a trustworthy place. The caregiver should not worry about overly indulging a child’s need for comfort, contact, or stimulation. This view is in sharp contrast with the Freudian view that a parent who overly indulges the infant by allowing them to suck too long or be picked up too frequently will be spoiled or become fixated at the oral stage of development.

Problems establishing trust:  Consider the implications for establishing trust if a caregiver is unavailable or is upset and ill-prepared to care for a child. Or if a child is born prematurely, is unwanted, or has physical problems that make them less desirable to a parent. Unwanted pregnancies can be experienced by busy, upper-middle-class professional couples as well as young, unmarried mothers or couples amid relational strains. Under these circumstances, we cannot assume that the parent will provide the child with a feeling of trust. However, remember that children can also exhibit strong resiliency to harsh circumstances. Resiliency can be attributed to certain personality factors, such as an easy-going temperament and receiving support from others. So, a positive and strong support group can help a parent and child build a strong foundation by offering assistance and positive attitudes toward the newborn and parent.

Autonomy vs. shame and doubt:  As the child begins to walk and talk, an interest in independence or freedom replaces a concern for trust. The toddler tests the limits of what can be touched, said, and explored. Erikson believed that toddlers should be allowed to explore their environment as freely as safety permits and, in so doing, will develop a sense of independence that will later grow into self-esteem, initiative, and overall confidence. Suppose a caregiver is overly anxious about the toddler’s actions for fear that the child will get hurt or violate others’ expectations. In that case, the caregiver can tell the child they should be ashamed of their behavior and instill a sense of doubt in their abilities. Parenting advice based on these ideas would be to keep your toddler safe but let them learn by doing. A feeling of pride seems to rely on doing rather than being told how capable one is (Berger, 2005).

We have explored the dramatic story of the first two years of life. Rapid physical growth, neurological development, language acquisition, the movement from hands-on to mental learning, an expanding emotional repertoire, and the initial conceptions of self and others make this period of life very exciting. These abilities are shaped into more sophisticated mental processes, self-concepts, and social relationships during early childhood.

Berger, K. S. (2001). The developing person through the life span. New York: Worth.

Berger, K. S. (2005). The developing person through the lifespan(6th ed.). New York: Worth.

Berk, L. E. (n.d.). Development through the lifespan(4th ed.). Boston: Allyn and Bacon.

Bruer, J. T. (1999). The myth of the first three years: A new understanding of early brain development and lifelong learning. New York: Simon and Schuster.

Chess, S., & Thomas, A. (1996). Temperament: Theory and practice. New York: Brunner/Mazel.

Children’s Welfare. (1998). Welfarem-L Digest, June 25. Retrieved August 10, 2006, from [email protected]

Hart, S., & Carrington, H. (2002). Jealousy in 6-month-old infants. Infancy, 3(3), 395-402.

LeVine, R. A., Dixon, S., LeVine, S., Richman, A., Leiderman, P. H., Keefer, C. H., & Brazelton, T. B. (1994). Child care and culture: Lessons from Africa. New York: Cambridge University Press.

O’Connor, T. G., Marvin, R. S., Rotter, M., Olrich, J. T., Britner, P. A., & The English and Romanian Adoptees Study Team. (2003). Child-parent attachment following early institutional deprivation. Development and Psychopathology, 15, 19-38.

Sen, M. G., Yonas, A., & Knill, D. C. (2001). Development of infants’ sensitivity to surface contour information for spatial layout. Perception, 30, 167-176.

Stack, D. M. (2010). Touch and Physical Contact during Infancy: Discovering the Richness of the Forgotten Sense. The Wiley-Blackwell Handbook of Infant Development, 532-567

Sullivan, R., Perry, R., Sloan, A., Kleinhaus, K., & Burtchen, N. (2011). Infant bonding and attachment to the caregiver: insights from basic and clinical science. Clinics in perinatology, 38(4), 643–655. doi:10.1016/j.clp.2011.08.011

Van Ijzendoorn, M. H., & Sagi, A. (n.d.). Cross-cultural patterns of attachment. In J. Cassidy & P. R. Shaver (Eds.), Handbook of attachment: Theory, research, and clinical applications (pp. 713-734). New York: Guilford.

Webb, S. J., Monk, C. S., & Nelson, C. A. (2001). Mechanisms of postnatal neurobiological development: Implications for human development. Developmental Neuropsychology, 19, 147-171.

Attribution

Sections Pain and Touch , Taste and Smell , and Piaget and Sensorimotor  minorly adapt content from  L ifespan Development by Lumen Learning and adapted by Randa Elgendy, Jenna Ernst, and Michelle Gagnon, licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted. Infant Sleep  minorly adapts content from Sleep and Health from Lifespan Development , licensed under multiple Creative Commons licenses. All remaining content is an adaptation of Developmental Psychology Copyright © by Lumen Learning and Bill Pelz Herkimer. It is licensed under a Creative Commons Attribution 4.0 International License , except where otherwise noted, lightly edited for clarity and to resolve errors, and updated throughout with new images and multimedia.

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Concepts for Care: 20 Essays on Infant/Toddler Development and Learning

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Human Infancy … and the Rest of the Lifespan

Marc h. bornstein.

Child and Family Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Public Health Service

Human infancy has been studied as a platform for hypothesis and theory testing, as a major physiological and psychological adjustment, as an object of adults’ effects as well as a source of effects on adults, for its comparative value, as a stage of life, and as a setting point for the life course. Following an orientation to infancy studies, including previous reviews and a discussion of the special challenges infants pose to research, this Annual Review focuses on infancy as a foundation and catalyst of human development in the balance of the life course. Studies of stability and prediction from infancy illustrate the depth and complexity of modern research on infants and provide a long-awaited reply to key philosophical and practical questions about the meaningfulness and significance of infancy.

HUMAN INFANCY

He who … considers things in their first growth and origin . . . will obtain the clearest view of them. -- Aristotle (350 B.C.E.), Politics, Part Two

Human infancy has always offered a certain romantic and simultaneously enigmatic attraction: All of us have been infants, yet perceptions, thoughts, and feelings of our infancy are seemingly lost to us. Infants are irresistible to our senses, engaging of our intellect, and moving to our emotions. Infants are completely dependent and under our care, and the results of our actions towards them become embodied in them. Infancy represents a beginning in which much is invested theoretically, psychologically, and personally. Formal studies of infancy have largely concerned delineating the status of different characteristics (constructs, structures, functions, and processes) in early life. Focusing on characteristics so close to the start, investigators of infancy are also naturally concerned with how biological and experiential forces fuse to shape our origins as well as the unfolding course of future development.

Infancy encompasses only a fraction of the average person’s expected life span, but infancy is characterized by remarkable physiological, physical, and psychological changes, many of which are evident even on casual observation. Within this brief period, the child’s length and weight multiply, and the child changes from an immature being unable to move his or her limbs in a coordinated manner to one who can purposefully control complicated sequences of muscle contractions and flexions necessary to grasp and walk, and from an unintelligible babbler to a sentient being who can verbalize needs and wishes with abundant clarity.

As the baby grows into the child, and the child eventually into the adult, exploring and explaining what transforms as the individual develops from infancy to maturity, and what remains stable and predicts the future person have constituted challenging tasks to philosophy, biology, and psychology. A reply to them is the principal topic of this Annual Review .

DEFINITION, HISTORY, CHALLENGE, AND ORIENTATION

What is an infant? What were the origins of infancy studies? The period of life called infancy is somewhat ambiguous and arbitrary; however, the Latinate root of infant, in + fans (non-speaker), ties the definition to a psychosocial event, viz. the onset of language, rather than to physical characteristics, weaning or walking, educational requirements, or vagaries of legal opinion. For purposes of this review, infancy encompasses roughly the first year of postnatal life.

In response to a note on language acquisition by Taine (see Kessen 1965 ), Charles Darwin (1877) published in the English journal Mind “A Biographical Sketch of an Infant.” The notes that constituted this account of the first years of his firstborn son William Erasmus (Doddy) had been recorded in notebooks almost 40 years earlier. Darwin’s foremost roles in the origins and descent of comparative psychology generally, of developmental science specifically, and of infant studies particularly are by now legendary ( Lerner et al. 2011 ). In the years following Darwin’s publication, a plethora of “baby biographies” appeared, and infancy studies blossomed ( Bornstein, Arterberry, & Lamb 2013 ).

Previous Reviews

Landmark reviews and integrations of the infancy literature to date include Kessen, Haith, and Salpatek’s (1970) overview in Mussen’s third edition of Carmichael’s Manual of Child Psychology , entitled “Infancy: A Bibliography and Guide.” Their survey approach appended more than 2,000 references to works on infants appearing to that time. Stone, Smith, and Murphy’s (1973) The Competent Infant built on Kessen et al., excerpting important original works. Haith and Campos (1977) updated the bibliography in their “Infancy” chapter with copious additional references in the first Annual Review of infancy, and Hay’s last Annual Review organized progress in infancy studies to 1986. In the roughly quarter-century since then, much has happened, and infants have grown up. Articles, essays, chapters, monographs, and books on infancy have appeared at an ever quickening pace. Notable periodic compilations focused on academic approaches to infancy (not trade books) include Haith and Campos’s (1983) Infancy and Developmental Psychobiology , Osofsky’s (1987) Handbook of Infant Development , and Rosenblith’s (1992) In the Beginning ; they have been supplanted by more contemporary treatments, including, Fogel’s (2007) Infancy: Infant, Family, and Society , Bremner and Wachs’s (2010) Handbook of Infant Development , and Bornstein et al.’s (2013) Development in Infancy: A Contemporary Introduction. Several scientific journals, Infancy , the Infant Mental Health Journal , and Infant Behavior and Development , to name a few, are now devoted exclusively to infancy and enjoy robust publication; of course, infant studies also prominently populate a host of other academic periodicals in psychology and allied disciplines. These trends support Haith and Campos’s (1977) valediction that the “allocation of the whole chapter in the Annual Review of Psychology to ‘Infancy’ is only one of many indications that the field has come into its own” (p. 251).

Thus, the literature in infancy is reviewed periodically, but not previously from the perspective that is advanced here. This Annual Review looks at infancy as a setting point in the life course. It has not been possible to do so before now because appropriate longitudinal data on the same participants collected in one study beginning in infancy and extending forward had not yet reached a critical mass.

Challenges of Studying Infants

How much we have learned about infant behavior and development, in approximately the last half-century, is testimony to the ingenuity, patience, and persistence of researchers in meeting and overcoming the formidable challenges posed by infants themselves. First and foremost, infants are by definition nonverbal (but not, of course, noncommunicative), and they are also, especially in the early months of life, motorically incompetent, emotionally labile, and subject to rapid fluctuations in behavioral state. Unlike adults, infants are not motivated to perform for researchers. Other problems too vex investigators like infants’ like short attention spans and their limited response repertoires.

Yet, infants are also important and attractive to study, for a host of reasons spelled out immediately below, not the least of which is their role in the balance of the life span, the principal subject here. The impediments infants present have stimulated researchers to develop strategies geared to overcome various communication barriers that naturally but infelicitously separate infants from the rest of us. Through intense appeal and decades of rigorous investigation, infants have slowly divulged their many secrets. This glimpse into the heretofore private world of infancy, and what it portends for the future, constitutes one of the notable achievements of modern developmental science.

Seven Types of Infancy Studies

Infants contribute to psychological inquiry in the “magical number seven” ( Miller 1956 ) major ways. Here, I touch on six of the seven types very briefly and then dwell on the seventh in detail. Each type merits extended treatment, which is not possible within the confines of an Annual Review . Amplification of one illustrates the breadth and depth of all.

First, as infancy provokes enduring philosophical, juridical, and social dispute and question, it has been the subject of continuing theoretical interest. Because infancy is a period of life that precedes the onset and influence of (much) experiences, for example, traditional nature-nurture debates have turned to infants. A principal task of infancy is radical adaptation from the secure comfort of the intrauterine environment to the kaleidoscopic extrauterine universe. Therefore, second, infancy is a major physiological and psychological adjustment. Third, adults wield extraordinary and nearly limitless control over infants in part because infancy is a period of both helplessness and plasticity. Aside from genetic bequest, caregivers exercise continuing and powerful influence over infants in their roles as ministrators, socializers, and educators. However, fourth, human infants are equally powerful stimuli to adults. Infants inspire song, poetry, literature, humor, art, and Annual Reviews. It is only for heuristic purposes that the otherwise inextricable mutuality between infants and adults into “effects on” and “effects of” can be separated. Transactions rule life: the level at which parents pitch the complexity of speech to their infant depends on the infant’s display of understanding, and infants’ comprehension depends on the complexity of speech addressed to them. Fifth, infancy is a natural arena for comparison of human abilities, behaviors, and development relative to newborns of other species, and, because many sorts of experimentation with human infants fall outside of ethical bounds, comparative animal models of infancy are common. Sixth, infancy appears to be a distinct stage of life, based on biological, cognitive, and social data, and so is meritorious of study in its own right. Infants do not speak, whereas children do; infants creep and crawl, whereas children walk and run. Many outstanding developmental theorists—Freud, Piaget, Erikson, and Werner—have championed stage theories of development, and all identified infancy as one. Finally, but not lastly, infancy has been studied as a basis of stability in development and prediction of the future life course.

STABILITY AND PREDICTION FROM INFANCY

The concept of development is most readily associated with change ( Block & Block 2006a Kagan 1976 , 1998 , Wohlwill 1973 ). As the child rapidly grows from the infant, change in many developmental characteristics are prominent and observable. The measured values of characteristics plotted across age define their developmental functions, and the species-general developmental function of many characteristics (from height to language) is discontinuous ( Emmerich 1964 ).

The other side of the developmental coin to change is consistency, manifest as continuity and stability. In actuality, consistency may be more parsimonious and orderly than change, and many characteristics of human development remain (more or less) consistent over time or connect in regular ways to later points in development. Consistency qua continuity describes maintenance of the group mean level of a characteristic over time; consistency qua stability describes maintenance in the ranks of individuals in a group with respect to the expression of a characteristic over time ( Bornstein & Bornstein 2008 , Hartmann, Pelzel, & Abbott 2011 ). Thus, a stable characteristic is one that some individuals demonstrate at a relatively high level at time 1 (infancy) and again at a relatively high level at time 2 (maturity). Stability has many variations and interpretations. Homotypic stability expresses maintenance of rank order status on an identical characteristic from time 1 to time 2 (e.g., vocabulary size at 12 months and at 12 years). Heterotypic stability or predictive validity expresses maintenance of rank order status between two related, but not identical, characteristics. The two may be related because they share the same underlying process (e.g., vocabulary size at 12 months and reading ability at 12 years both reflect language). Stability and prediction share their side of the developmental coin.

A fundamental conceptual issue that has framed debates in theory and research across the history of developmental science has concerned stability and prediction. What do individual differences in infants tell us about the human being’s future development? The terms “seeds,” “precursors,” “potentials,” and “Anlagen” are commonly applied to constructs, structures, functions, and processes in infants that foretell later characteristics. This Annual Review deliberates on questions of stability and prediction from infancy.

Why and How Developmental Science is Concerned with Stability and Prediction from Infancy

The long-term significance of infancy has engendered intense dispute between two polar theoretical stances. Some authorities rail against so-called “infant determinism” and contend that infancy is not particularly important because the status of the infant or experiences in infancy have little (if any) long-term significance. That is, infant characteristics and experiences leave no irreversible signs on people’s lives but are supplanted later in development. This position emphasizes discontinuities and instabilities between infancy and maturity: Infancy is disconnected from the balance of the life course, and infant characteristics and experiences are peripheral or ephemeral or inconsequential in the sense that they exert little or no enduring effect ( Bruer 2002 , Clarke & Clarke 2000 , Kagan 1998 , Lewis 1997 ). Empirical support for this point of view typically consists of failures to find lagged associations between the same or different characteristics in infancy and maturity, demonstrations of the recovery of functioning from early adversity or deprivation, as well as failures of early experiences or interventions to show sustained effects.

However, others theorists contend that infancy is part of a seamless and united lifeline and that characteristics and experiences in infancy are not only important in themselves but are also crucial to later life. For these theorists, biological functioning, intellectual predilections, personality inclinations, and social orientations in infancy set enduring patterns. Arguments for the specialness of infancy in these ways derive from a diverse and impressive array of theoretical starting points, including psychoanalysis, behaviorism, constructivism, ethology, neuropsychology, attachment, and systems theory. For example, Freud (1949) focused attention on infancy, suggesting that the ways babies are treated establish lifelong personality traits, and Erikson (1963) theorized that the resolution of developmental crises in infancy have implications for the way the person negotiates successive stages of development. For theorists like Watson, Skinner, and Dollard and Miller, learning in infancy is important because it occurs first and promotes easy and rapid later learning. They asserted that early and simpler behavior patterns underlie later and more complex ones. Piaget (1970) likewise opined that advanced developmental capacities build on elementary ones of very early life, all the way back to infancy. For their part, ethologists and embryologists from Lorenz and Tinbergen to Gottlieb emphasized the lifelong legacy of infant experiences (as in sensitive periods; Bornstein 1987 , 1989 ). Bowlby, Ainsworth, and their successors ( Sroufe, Egeland, Carlson, & Collins 2005 ) in turn theorized that attachment experiences and classification in infancy augur future cognitive development, personality, and social relationships. Furthermore, modern systems theorists contend that development consists of hierarchically organized characteristics that incorporate earlier emerging ones ( Lewontin 2005 ). Finally, contemporary life-course theory brackets human development as extending from the prenatal period and infancy to maturity and death. Understanding development requires examining characteristics and experiences over long periods of time to capture how later life depends on early life trajectories ( Elder 1998 , Elder, Shanahan, & Jennings 2015 ).

Infancy has therefore held a certain significance for those interested in stability and prediction, even when the characteristics and long-term effects of experiences from infancy are neither obvious nor direct. Developmental science generally carries three burdens—description, explanation, and prediction. Of these, prediction is the most thorny and problematic (as many a homespun philosopher has quipped: “prediction is difficult, especially if it’s about the future”). However, prediction from infancy has many vital purposes and benefits, its moral and ethical consequences notwithstanding. To put their ambit and value most succinctly, stability and prediction deepen psychological understanding, open the possibility of individual assessment, and lead to greater economy of decision making and more efficacious distribution of resources. These are theoretically worthy as well as highly practical goals.

Stability and prediction are also important constructs for developmental science per se. In interpreting the theoretical significance of a characteristic, it is essential to determine whether the characteristic represents something enduring in individuals or is better viewed as linked to a particular developmental time point or context, with few or no future implications. Knowledge about which characteristics are stable or predictive, beginning when, and over what periods of time, is foundational in the study of development.

Findings of stability and prediction tell us about the nature and overall ontogenetic course of a characteristic. Whether individuals maintain their order on some characteristic, or a characteristic is predictive through time, informs not only about individual variation, but contributes to understanding of the origins, nature, and future of that characteristic as well. Is past performance the best predictor of future performance? Insofar as a characteristic is stable or predictive, we know that individuals who do well or poorly with respect to that characteristic at one time are likely to do well and poorly again later. Moreover, stable and predictive early characteristics tend to shape later emerging ones. Infants who know more words at 1 year tend to know more words at 2 years, and 2-year-olds who know more words may be at a long-term advantage because knowing more words speeds learning to read, improves verbal comprehension, and eventuates in more advanced written language skills ( Marchman & Fernald 2008 ).

Stability and prediction are also meaningful because characteristics with such attributes in childhood signal developmental status to other people, thereby affecting the child’s environment and likely his or her own development. Interactants often adjust their expectations and behaviors to match another’s consistent characteristics (as when adults modify their language to harmonize with the language of a child). On the basis of stability and prediction, infants actively contribute to their own development.

Finally, most developmental scientists believe that individuals understand the world in unique ways that reflect their unique persons, interactions, and experiences. This perspective depends (in part, at least) on stable tendencies and capacities in the individual. In a nutshell, developmentalists are broadly interested in how characteristics manifest themselves in infancy and the developmental course of those characteristics – their stability and prediction through time. Characteristics that are stable or predictive in ontogeny are informative as to the nature of those characteristics per se as well as the individuals who possess them.

Historically, reports of stability and prediction have relied on simple or zero-order lagged correlations and regression analyses, comparing infants’ performance early in life with their performance years later as children, adolescents, or even adults. In addition, growing sophistication in the statistical armamentarium for estimating stability and prediction across time has welcomed latent growth curve modeling ( Asendorpf & van Aken 1999 , Blaga et al. 2009 , Bridgett et al. 2009 , Bridgett & Mayes 2011 , Hill-Soderlund & Braungart-Rieker 2008 , Pasco, Fearon, & Belsky 2011 ), path analysis ( Bornstein et al. 2006 , LaBuda, DeFries, Plomin, & Fulker 1986 ), hierarchical linear modeling ( Bada et al. 2007 , Shafir, Angulo-Barroso, Calatroni, Jimenez, & Lozoff 2006 ), and hazard analyses ( Frank et al. 2011 ). For temporally distal, developmental processes, moreover, tests of indirect paths between predictors and criteria are sometimes more sensitive, powerful, and theoretically appropriate than tests of simple direct relations ( Shrout & Bolger 2002 ). A developmental cascade, for example, defines a longitudinal relation in which a characteristic at time 1 is uniquely associated with another characteristic at time 2 separate from other intrapersonal and extrapersonal factors ( Masten & Cicchetti 2010 ). In cumulative processes, which refer to the growing implications of earlier characteristics or experiences for later outcomes, early individual differences are magnified in prediction ( DiPrete & Eirich 2006 ). That is, in some cases the linear model may be inadequate to the task of assessing stability or prediction, and other statistical techniques may be more appropriate for multi-level longitudinal analysis ( Bergman, Magnusson, & El-Khouri 2003 , Collins & Sayer 2001 , Little, Schnabel, & Baumert 2000 ).

Duncan et al. (2006) usefully described a continuum for evaluating the methodological rigor of studies such as those aimed at stability and prediction. At the popular end of the spectrum are correlational designs that analyze simple associations between measures in infancy and later outcomes, with few adjustments for confounding factors, and so this kind of research likely suffers from various biases. At the rare end are experiments in which infants are randomly assigned to treatment conditions and followed longitudinally; experiments can provide unbiased estimates of prediction (and, of course, are more appropriate to prediction than to stability). Between these extremes fall studies that employ techniques to reduce various biases (e.g., like omitted variables using fixed effects and instrumental variables regression) and natural experiments. Despite the burgeoning literature documenting stability and prediction (reviewed below), it is necessary to be cautious in drawing strong conclusions because still few studies have employed research designs or analytic methods that effectively and comprehensively address threats to internal validity. Increasingly, however, researchers are opting for designs and analyses that seriously address biases from diverse sources.

Furthermore, empirical studies of stability and prediction usually settle for data from only two assessment waves. However, it is less than desirable to discern patterns of stability and prediction from two assessments (i.e., whether stability and prediction stabilize at a nonzero value or approach zero in the limit). Following the logic in Fraley, Roisman, and Haltigan (2013) , a significant relation between measurements of some characteristic at time 1 and the same or a different characteristic at time 2 would seem to indicate that the characteristic is stable or predictive. However, conclusions about stability or prediction would vary depending on the resultant coefficient at other developmental waves. Suppose, on the one hand, that stability and prediction maintained to times 3, 4, and 5. This pattern would suggest that stability and prediction are enduring. Suppose, on the other, that stability or prediction attenuated at times 3, 4, or 5; that is, as the temporal interval increased, stability or prediction approached 0.00 in the limit. This pattern would suggest that, although the time 1 characteristic may play a role in the time 2 characteristic, the association eventually tempers, indicating that longer-term stability or prediction may be trifling. The two patterns have contrasting consequential implications ( McCartney & Rosenthal 2000 ).

Long-Term Stability and Prediction from Infancy

The infancy literature is replete with studies of stability and prediction assessments confined within the first year of life (e.g., Artzi et al. 2011 , Beebe et al. 2010 , Bridgett et al. 2009 , Fish 2001 ), and developmental science more generally abounds with studies that evaluate and substantiate stability and prediction after infancy (e.g., Asendorpf & van Aken 2003 , Gao et al, 2010a , Casey et al. 2011 , Caspi 2000 , Dennissen, Asendorpf, & van Aken 2007 , Guerin, Gottfried, & Thomas 1997 , Martinez-Torteya, Bogat, von Eye, & Levendosky 2009 , Reese, Jack, & White 2010 ). Notably, Bloom (1964) suggested that 50% of an adult intelligence is developed by 4 years of age, basing this conclusion on the strong statistical correlation between IQ at 4 years and IQ at 17 years. The Fels longitudinal study reported that IQ at 3 years predicted attained education and occupational status after 26 years ( McCall 1977 ). Block and Block (2006b) observed that preschool children who were relatively more anxious, indecisive, and prone to guilt were more likely to endorse conservative values when they were 23 years. Many reports now extend from childhood or adolescence well into late life ( Ashby & Schoon 2012 , Benson & Elder 2011 , Casey et al. 2011 , Gao et al. 2010b , Kell, Lubinski, & Benbow 2013 ). Among the oldest, active longitudinal studies, with birth years extending from 1903 to the 1920s, was Terman’s on a sample of talented children: by the 1990s, investigators who continued this project had completed 13 waves of data spanning 70 years ( Crosnoe & Elder, 2004 , Holahan & Sears, 1995 , Shanahan & Elder, 2002 ). Notably, however, past long-term longitudinal studies typically began in adolescence and often assumed that what transpired before—in the first years of life—was little consequential.

Because long-term longitudinal research generally was rare, and research beginning in infancy almost absent, it was not possible previously to answer questions about stability and prediction from infancy. This is unfortunate, because knowing more about which aspects of humanity are stable or predictive is (as argued above) vital to a full understanding of the nature and process of development. Now, however, examples from multiple domains have begun to populate the life course literature, and they reveal pervasive stabilities and predictions from the first year of life (or even before) to childhood, adolescence, and adulthood. To animate the discussion and broaden generalizations, the following sections illustrate stability and prediction from biological, physical, and motor domains of development, from perceptual, cognitive, and communicative domains of development, and from emotion, temperament, and social domains of development. Infant experiences are also considered. Most are recent efforts, but where available, each section begins with reference to classical studies from the 1960s–1970s. In which domains of development are characteristics preserved from infancy? Several, it turns out.

Biological, Physical, and Motor Development

Interest in stability and prediction in biology was reinvigorated when events occurring in early postnatal (or even prenatal) life were traced and found to have long-lasting effects on behavior and health. Barker and his colleagues in the 1980s unearthed an association between low birth weight (LBW) and ischemic heart disease in adulthood ( Barker & Osmond 1986 ). The so-called Barker Hypothesis identified the general importance of early determinants of adult disease. A wealth of data has been published since showing an inverse association between infant size at birth and adult blood pressure, type 2 diabetes, heart disease, and enhanced response to stress ( Barker, Eriksson, Forsén, & Osmond 2002 , Huxley, Shiell, & Law 2000 , Jones et al. 2006 , Hales et al. 1991 , Phillips et al. 2005 ). More generally, this line of research has led to articulation of the developmental origins of health and disease paradigm (DOHaD; Barker 1998 , Bateson et al. 2004 , Gluckman & Hanson 2006 ).

A frequent design encountered in the biological literature consists of between-group comparisons of “treatment” children, adolescents, or adults versus controls where the treatment (preterms vs. fullterms, toxin exposed vs. nonexposed) happened in the first year of life, or sometimes earlier. Publications appear periodically as successive waves of data collection are completed ( Corapci, Radan, & Lozoff 2006 , Gahagan, Yu, Kaciroti, Casillo, & Lozoff 2009 , Geva et al. 2009 , Hane, Henderson, Reeb-Sutherland, & Fox 2010 , Lorenz et al. 2009 , McAnulty et al. 2010 , Paradise et al. 2007 , van Baar, Ultee, Gunning, Soepatmi, & de Leeuw 2006 ). The deduction is that any mature differences between the groups are ascribable to continuing infancy (or prenatal) characteristics or experiences (rather than any intervening factor or experience). These studies concern themselves with an eclectic variety of outcomes, linking different biological, physical, or motor characteristics in the first year of life to many different later criteria. For example, preterm infants, relative to term infants, later in life show anatomical differences in the brain structure, are at increased risk of diabetes and heart disease, more likely display impaired motor skills, higher heart rate, attention and cognition problems, delayed language, low IQs, and developmental and learning disabilities, and they experience increased problems in social and academic functioning ( Aziz, Schlindwein, Wailoo, Biala, & Rocha 2012 , Bhutta, Cleves, Casey, Cradock, & Anand 2002 , Caravale, Tozzi, Albino, & Vicari 2005 , Foster-Cohen, Edgin, Champion, & Woodward 2007 , Gayraud & Kern 2007 , Kerkhof, Breukhoven, Leunissen, Willemsen, & Hokken-Koelega 2012 , Mewes et al. 2006 , Phillips & Barker 1997 , Saigal 2000 , Saigal, Hoult, Streiner, Stoskopf, & Rosenbaum 2000 , Salt & Redshaw 2006 , Sansavini et al. 2006 , Schothorst & Egeland 1996 , Shenkin, Starr, & Deary 2004 , Spassov et al. 1994 , Taylor, Klein, & Hack 2000 Taylor, Klein, Minich, & Hack 2000 , van de Weijer-Bergsma, Wijnroks, & Jongmans 2008 , Woodward, Mogridge, Wells, & Inder 2004 ). Children born before 26 weeks gestation and followed until 6 years report higher rates of cognitive impairment compared their classmates ( Marlow, Wolke, Bracewell, & Samara 2005 ). Smaller babies also grow up to be sadder adults: Birth weight has been linked to both depression and anxiety over 40 years ( Colman, Ploubidis, Wadsworth, Jones, & Croudace 2007 ). Long-term follow-up studies show preterm infants (even those without medical disabilities) have as adults lower educational attainment and income, are less likely to establish a family, and are more likely to receive Social Security benefits ( Moster, Lie, & Markestad 2008 ). Infancy is also a particularly vulnerable period, for example to malnutrition, and growth problems forecast poor cognitive and social functioning in middle childhood and adolescence ( Grantham-McGregor & Fernald 1997 , Guerrant et al 1999 , Kar, Rao, & Chandramouli 2008 ). Postnatal exposure to various toxins, like PCBs, has also shown adverse behavioral and emotional effects as, for example, in decreased sustained activity and high-level play and increased withdrawn and depressed behavior, aggression, and emotional reactivity ( Lai et al. 2002 , Perera et al. 2012 , Rogan & Gladen 1991, Vreugdenhil, Slijper, Mulder, & Weisglas-Kuperus 2002 ).

A more straightforward approach in these domains has been to assess an hormonal or autonomic or central nervous system characteristic in infancy and relate it directly to the same or another (related) characteristic later in development. The diversity is striking. Higher levels of testosterone at 3 months of age predict greater penile growth in early childhood ( Boas et al. 2006 ). Heart rate (HR), heart rate variability (HRV), and parasympathetic control measured in the first year of life are stable up to 5 years ( Bar-Haim, Marshall, & Fox 2000 , Bornstein & Suess 2000 , Calkins & Keane 2004 ). Skin conductance activity in typically developing 1-year-olds predicts mother-rated aggressive behavior problems at 3 years ( Baker, Shelton, Baibazarova, Hay, & van Goozen 2013 ). Thus, hormones and measures of autonomic function during infancy carry through to multiple measures of physical, autonomic, and behavior in childhood and later. Together, these results provide evidence of early postnatal origins of more mature development.

Likewise, evoked response potentials (ERP) in the first year of life predict children’s later language, cognitive, and socioemotional development ( van der Feest 2010 ). Infants who show less neural activity to non-native contrasts at 7.5 months have larger vocabularies at 24 months, suggesting that infants who are more attuned to the sounds in their language are better at learning words ( Kuhl 2009 ); auditory ERPs of English-exposed American infants in response to both Spanish and English voicing contrasts at 11 months of age predict the number of words children produce at 18 through 30 months of age ( Kuhl & Rivera-Gaxiola 2008 ; see also Garcia-Sierra et al. 2011 , Rivera-Gaxiola et al. 2005 ); cortical auditory ERPs at 6 and 9 months predict language at 3 and 4 years ( Choudhury & Benasich 2011 ); a discriminant function analysis of the brain waves of newborns predicts the classification of 8-year-old children into normal- and low-language performance groups with about 80% accuracy ( Molfese 2000 ). Brain electrical activity at 8 months also predicts working memory at 4.5 years ( Wolfe & Bell 2007 ). Stability in frontal brain activity asymmetry at 10 months predicts higher externalizing and internalizing behaviors as rated by mothers at 2.5 years ( Smith & Bell 2010 ), and infants with right frontal EEG asymmetry show higher levels of anxiety and less ability to regulate their emotions in middle childhood ( Hannesdottir, Doxie, Bell, Ollendick, & Wolfe 2010 ).

MRI can be used to measure the sizes of brain structures, and these measures in young infants also predict later language abilities ( Ortiz-Mantilla, Choe, Flax, Grant, & Benasich 2010 ). fMRI studies allow precise localization of brain activity and show remarkable similarity in the structures responsive to language in infants and adults ( Dehaene-Lambertz, Dehaene, & Hertz-Pannier 2002 , Dehaene-Lambertz & Hertz-Pannier 2006 ).

A related characteristic shown to be predictive in the long-term is physical status of the infant. Low birth weight (LBW; < 2kg) is predictive of motor problems at 16 years ( Whitaker et al. 2006 ); height and head circumference at 1 year predict IQ and neurodevelopmental outcomes at 9 and 10 years ( Fattal-Valevenski et al. 2009 ); and being small for gestational age has an independent effect on 16-year full-scale IQ, controlling for other pre- and postnatal risk factors ( Lorenz et al. 2009 ). Small for gestational age newborns have higher HR and lower HRV than newborns adequate for gestational age; babies born with low birth weight have lower HRV in childhood and adulthood as compared to babies born with normal weight; and those born preterm have higher HR at 18 to 24 years, as compared to normal controls ( Aziz et al. 2012 , Kerkhof et al. 2012 , Phillips & Barker 1997 , Spassov et al. 1994 ).

Even infantile colic (excessive crying in an otherwise healthy baby classically defined by Wessel criteria as at least 3 hours of crying at least 3 days a week for 3 weeks; Wessel, Cobb, Jackson, Harris, & Detwiler 1954 ) appears to be associated with migraines in children aged 6 to 18 years ( Gelfand, Thomas, & Goadsby 2012 , Guidetti, Ottaviano, & Pagliarini 1984 ). Other early childhood periodic syndromes (benign paroxysmal vertigo or benign paroxysmal torticollis) are thought to be expressions of genes that later in life also manifest as migraine ( Giffin, Benton, & Groadsby 2002 ).

Early on, Gesell (1937) reported patterns of individuality and consistency in motor behavior from the first to the fifth year of life. Movement and coordination at between 1.5 and 4.5 months are consistent with the later female advantage in finer motor skill and male advantage in gross motor activity ( Piek, Gasson, Barrett, & Case 2002 ). Movement at 4 months predicts motor and cognitive status at 2 years ( Rose-Jacobs, Cabral, Beeghly, Brown, & Frank 2004 ); motor control at 3 months, parent-reported attention problems at 8 years ( Friedman, Watamura, & Robertson 2005 ); manipulative skill at 4 months ( Kohen-Raz 1967 ), the Beery Developmental Test of Visual Motor Integration (VMI; eye-hand coordination) at 5 years ( Siegel 1983a ); activity at 5 months, attention and play after 1 year ( Tamis-LeMonda & Bornstein 1993 ); psychomotor status at 6 months, developmental profiles at 2 years ( McCall, Hogarty, & Hurlburt 1972 ); and motor control at 3 months, attention at 8 years ( Friedman et al. 2005 ). A large-scale ( N = 374) normative prospective 14-year longitudinal multivariate multisource controlled study showed that infants who were more motorically mature and who explored more actively at 5 months achieved higher levels of academic achievement at 14 years through conceptually related and age-appropriate measures of psychometric intelligence at 4 and 10 years and academic achievement at 10 years. This developmental cascade applied equally to girls and boys and was independent of children’s behavioral adjustment and social competence, mothers’ supportive caregiving, verbal intelligence, education, and parenting knowledge, and the material home environment ( Bornstein, Hahn, & Suwalsky 2014 ).

Similarly, the Bayley Scales Psychomotor Development Index (PDI) in the first year of life predicts expressive language at 2 years ( Siegel, 1981 ), 3 years ( Siegel, 1979 ), and 4 years ( Siegel, 1982 ) and the McCarthy GCI at 6 years ( Siegel, 1983a ); 4-month PDI, 6-year VMI ( Siegel 1989 ); and 8-month PDI and 1-year motor development, 7-year intellectual level ( Broman, 1989 ).

Perceptual, Cognitive, and Communicative Development

A second developmental domain in which long-term stabilities and predictions are being documented includes perception, cognition, and communicative functions in the first year of life. Neonatal look duration relates to selective attention at age 12 years ( Sigman, Cohen, Beckwith, Asarnow, & Parmelee 1991 ), and ocular reaction time (RT) to targets in a visual expectation paradigm at age 3.5 months relates to ocular RT at age 4.5 years ( Dougherty & Haith 1997 ). Perceiving a unique face in an anomalous social experience (still-face) at 5 months predicts face recognition at 1.5 years ( Bornstein, Arterberry, & Mash 2004 ). Despite years of visual input being available to both hemispheres following corrective surgery for congenital cataracts that blocked all patterned input to both the left and right eyes in infancy, people later show impaired face processing in the right but not the left hemisphere ( Le Grand, Mondloch, Maurer, & Brent 2003 ). Long-term perceptual effects are not restricted to vision: Infants who nursed for 6 weeks from mothers who placed a balm with a distinctive odor on their nipples retained a representation of the odor for at least 18 months after they had stopped nursing ( Allam, Soussignan, Patris, Marlier, & Schaal 2010 ), and 6.5-month-olds sitting in a dark room who reached out on hearing a sound from the space in front of them reached out when they returned to the lab and were played the sound 2 years later ( Keen & Berthier 2004 ); in both instances, infants without the experience did not react.

Studies of stability in cognition have demonstrated consistencies as well. 6-month-olds’ performance in an action interpretation task predicts their performance on theory of mind tasks at 4 years ( Aschersleben, Hofer, & Jovanovic 2008 ). Infant information processing abilities in the first 6 months of life in three domains (attention, speed, and memory) relate to language and executive functions (working memory, inhibition, and shifting) at age 1.8 (Dixon & Smith 2008), age 4 ( Cuevas & Bell 2013 , Courage, Howe, & Squires 2004 ), and age 11years ( Rose, Feldman, & Jankowski 2012 ), academic achievement at age 14 years ( Bornstein et al. 2012 ), span of apprehension and intelligence at age 18 years ( Sigman, Cohen, & Beckwith 1997 ), and IQ and academic achievement at age 21 years ( Fagan, Holland, & Wheeler 2007 ), even after contributions of biological and psychological third variables have been partialed ( Bornstein et al. 2012 , Laucht, Esser, & Schmidt 1994 ).

The Bayley Scales are often interpreted as a general measure of infant cognition. The Bayley Scales Mental Development Index (MDI) at 4 to 12 months predicts the Reynell Developmental Language Scales (RDLS) performance at 2, 3, and 4 years ( Siegel, 1979 , 1981 , 1982 , 1983a , b , 1985a , b ), the Bayley MDI administered at 3 months predicts the Stanford-Binet at 3 years, the McCarthy Scales of Children’s Abilities (MSCA) at 4 years, and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) at 4, 5, and 6 years ( Wilson 1978 ).

Infants in the first year of life do not command much in the way of verbal abilities per se; however, some speaking patterns we acquire early appear to last a lifetime ( Flege 1991 ). Longitudinal studies demonstrate stability and prediction from a variety of early preverbal skills to measures of later language. Indian infants adopted by American families and only exposed to English relearn Indian-dialect phonemes more quickly than American children who had never heard the Indian phonemes ( Singh, Liederman, Mierzejewski, Barnes 2011 ); speech perception at 6 months predicts language acquisition (word understanding, word production, and phrase understanding) at 2 years ( Tsao, Liu, & Kuhl 2004 ) and Fernald, Perfors, & Marchman 2006 ), and speech discrimination at 6 months predicts phonemic awareness scores at age 5 years ( Cardillo 2010 ); speech processing performance (segmenting words from fluent speech) before 12 months predicts language assessed at 6 years ( Newman, Ratner, Jusczyk, Jusczyk, & Dow 2006 ). The trajectory of learning to discriminate vowels between 7 and 11 months predicts children’s language abilities and pre-literacy skills at age 5 years, an association that holds regardless of SES as well as the level of children’s language skills at 18 and 24 months of age ( Cardillo Lebedeva & Kuhl 2009 ). Infants’ early phonetic perception ( Kuhl et al. 2008 , Kuhl, Conboy, Padden, Nelson, & Pruitt 2005 , Rivera-Gaxiola, Silva-Pereyra, & Kuhl 2005 , Tsao et al. 2004 ), their pattern-detection skills for speech ( Newman et al. 2006 ), mismatch responses to native-language sounds ( Kuhl et al. 2008 ), and processing efficiency for words ( Fernald et al. 2006 ) have all been linked to advanced later language abilities. Studies of communication skills and expressive vocabulary at 8 and 12 months also show predictive relations to mother-reported child symbolic use of objects at 2 years ( Reilly et al. 2009 ); and 12-month-olds’ vocabulary as measured by the CDI predicts their 4-year verbal IQ ( Blaga et al. 2009 , Domsch et al. 2009 ). Finally, 3-month-old boys’ differential vocalizations to their mothers versus a stranger predicts cognitive and academic functioning at 12 years, high-school grade point average and SAT scores, and education completed by 28 years ( Roe, 2001 ).

Emotions, Temperament, and Social Development

A third developmental domain of long-term study includes evaluations of emotions, temperament, and social interactions in the first year as predictive of child, adolescent, or adult criteria. Emotions are normally thought to be transient and fleeting. In consequence, emotions per se might not be expected to cast a long shadow. Nonetheless, low approach behaviors and poor inhibitory control at 4 months have been linked to internalizing behaviors at 4 years ( He et al. 2010 ), and 3- to 4-month-olds who cry during experiments are more likely to be fearful and anxious adolescents ( Ohr, Feingold, & Fagen 2006 ). Institutionalized care beyond 1 year appears undermine emotion identification and labeling in 4- to 5-year-olds ( Camras et al. 2006 ).

Chess followed children at regular intervals from infancy to young adulthood to try to understand the temperamental origins of later behavioral disorders. Their findings suggest that some aspects of early temperament had long-term consequences. For example, the majority (70%) of difficult infants in their sample manifest behavior problems later in life ( Thomas, Chess, & Birch 1970 ). Temperamental difficultness, irritability, and negativity themselves appear to be stable from the first year ( Rothbart & Bates 2006 ). Four-month behavioral inhibition, an infant temperamental style characterized by distress to novelty, predicts social wariness at 7 years (as moderated by maternal negative personality; Degnan, Calkins, Keane, & Hill-Soderlund 2008 ). In more normal bands of temperament, mother as well as father reports of activity level, smiling and laughter, distress to limitations, and fear at 6 months foretell behavioral adjustment at 5.5 years ( Komsi et al. 2006 ), and temperamental exuberance in 4-month-olds predicts 5-year-olds’ externalizing and surgency ( Degnan et al. 2011 ).

In one longitudinal study, 4-month-olds were classified as either high or low in reactivity (depending on levels of motor activity and distress in response auditory, olfactory, and visual stimuli) and were then examined at 14 and 21 months ( Kagan & Arcus, 1994 ), 4.5 years ( Kagan, Snidman, & Arcus 1998 ), and 7 years of age ( Kagan, Snidman, Zentner, & Peterson 1999 ). Temperamental reactivity was stable over time. Moreover, children classified as highly reactive in infancy were more likely to react fearfully to novel stimuli at 14 and 21 months than were children classified as unreactive; by 4.5 years, highly reactive children showed less spontaneity and sociability with adults; and by 7 years, highly reactive children were more likely to behave anxiously than were non-reactive children. In adolescence at 15 years of age, highly reactive infants had become shy and anxious ( Kagan 2013 ), and fMRI examinations at 21 years in the same sample revealed that previously inhibited children showed more amygdala activity than did previously uninhibited children when looking at novel, as opposed to familiar, faces ( Schwartz, Wright, Shin, Kagan, & Rauch 2003 ).

Infants’ expressions of smiling and laughter predict their anticipatory eagerness about upcoming positive events at the age 7 ( Rothbart 1988 , Rothbart, Derryberry, & Hershey 2000 ). Parent-reported infant reactivity to sensory stimulation at 10 months is related to social inhibition at 2 years ( Andersson, Bohlin, & Hagekull 1999 ); fear (distress to novelty) in infancy is associated with increased latency to approach later in childhood ( Rothbart & Mauro 1990 ). In early adopted children followed from infancy to adolescence, temperament was found to be stable over time ( Jaffari-Bimmel, Juffer, van IJzendoorn, Bakermans-Kranenburg, & Mooijaart 2006 ); and physical aggression, as reported by mothers and fathers, in a sample of children initially recruited at 12 months was moderately stable 1 year later ( Alink et al. 2006 ). Infant activity level predicts positive emotionality, and higher anger/frustration and low soothability-falling reactivity at age 7; and infants who show a short latency to grasp objects at 6.5, 10, and 13.5 months show high levels of positive anticipation and impulsivity as well as high anger-frustration and aggression at age 7 ( Rothbart et al. 2000 ). Putnam, Rothbart, and Gartstein (2008) reported stability for fine-grained scales and factor-level temperamental dimensions from the Infant Behavior Questionnaire-Revised to the Early Childhood Behavior Questionnaire to the Children’s Behavior Questionnaire.

Temperamentally difficult 1 year olds who experience negative and intrusive mothering show externalizing behavior at 3 years ( Belsky, Hsieh, & Crnic 1998 ); similarly, infants who are temperamentally difficult and experience harsh parental reactions as 4-year-olds show externalizing behavior in adolescence ( Bates et al. 1995 ).

Social Anxiety Disorder (SAD) causes the experience of intense fear and distress in social situations. Chronis-Tuscano and her colleagues (2009) investigated whether behavioral inhibition, a temperamental disposition to withdraw from unfamiliar social interactions, was an early sign of SAD. They measured temperament at ages 4 months, 24 months, 4 years, and 7 years. When the children were between the ages of 14 and 16 years, they were assessed for SAD. Onset for SAD was normally after 7 years. Temperament proved relatively stable from infancy to adolescence, and infants who showed early stable and high maternal-reported behavioral inhibition were most likely to show SAD by 14 to 16 years at age.

Across domains, temperament at 8 months predicts working memory at 4.5 years ( Wolfe & Bell 2007 ); exuberance in infancy (vigorous motor activity, babbling, and smiling) predicts sociability and risk taking at 5 years ( Lahat et al. 2012 ); hyperreactivity in the first months of life predicts periodic syndromes at 10-11 years ( Guidetti et al. 1984 ); and reactivity at 4 months correlates with ventromedial prefrontal structural brain differences at 18 years ( Schwartz et al. 2010 ).

The social status and social interaction style of infants have also been found to predict later development. In this area, infants’ attachment status (usually measured around or just after the child is 1 year) has been the focus of many follow-on longitudinal investigations. Developmentalists have been drawn to infant attachment especially out of reasoning that the security of the infant’s early relationships influences the ways in which the person relates to others during life after infancy ( Bowlby 1969 ; van IJzendoorn 2005 ). Main and Cassidy (1988) reported a high degree of stability between 12-month attachment assessments in the Strange Situation and 6-year assessments, and meta-analysis confirms that attachment status is moderately stable across (at least) the first 19 years of life ( Fraley 2002 ).

Expectations of its developmental spreading effects are borne out in studies that show that quality of infant attachment predicts later social relationships with siblings and peers ( Furman & Lanthier 2002 , Garner 2006 , Ladd & Pettit 2002 , Volling 2003 , Zimmermann, Maier, Winter, & Grossmann 2001 ). Indeed, different attachment types predict a variety of developmental outcomes. Secure infant-mother attachments at 12 months are associated with more accurate perception of emotion in faces ( Steele, Steele, & Croft 2008 ) and superior problem-solving abilities in diverse stressful and challenging contexts into the preschool years ( Sroufe et al. 2005 ). Babies with secure (Type B) attachments to their mothers are later more cooperatively playful when interacting with a friendly stranger and more popular and socially competent in their peer group in elementary school ( Sroufe et al. 2005 ). The quality of infant attachments also predicts school children’s perceptions of their relationships with teachers, underscoring both the long-lasting and broad impact of infant attachment status ( Howes, Hamilton, & Phillipsen 1998 , NICHD Early Child Care Research Network 2005 , 2006 ). For its part, insecure attachment in infancy and, in particular the disorganized/disoriented classification, predicts antisocial behavior in childhood ( Jafferi-Bimmel et al. 2006 ), PTSD symptoms at 8.5 years (McDonald et al. 2008), externalizing behaviors at 12 years ( Pasco Fearon & Belsky 2011 ), and compromised parent-adolescent relationships and increased likelihood of deviant behavior among youth ( Allen, More, Kuperminc, & Bell 1998 ). A core assumption of attachment theory is that individual differences in adult attachment styles emerge from individuals’ developmental histories ( Hazan & Shaver 1987 , Mikulincer & Shaver 2007 ). An age 18 follow-up of the NICHD SECCYD, a longitudinal investigation that tracked a cohort of children and their parents from birth, reported that individual differences in adult attachment styles could be traced to variations in infants’ caregiving environments in combination with other factors ( Booth-LaForce & Roisman 2012 , Fraley, Booth-LaForce, Roisman, Owen, & Holland 2013 ). Infant attachment security is associated with the security of participants’ romantic relationships in young adulthood ( Roisman, Collins, Sroufe, & Egeland 2005 ). Adults who classify themselves as secure are more likely to describe their early experiences with their parents as being affectionate, caring, and loving ( Hazan & Shaver 1987 ), whereas adults who classify themselves as insecure are more likely to describe their parents as cold or rejecting ( Collins & Read 1990 ).

Attachment classification is not the only long-term social style predictor from infancy. It has been recognized for some time that early (3-month) infant participation in interactions with their mothers predicts their later (6-year) intelligence ( Coates & Lewis 1984 ). Other socioemotional factors in infants appear to predict as well. For example, differences in infants’ perception of intentional agency at 12 months predicts their understanding of others’ theory of mind, mental states, and beliefs as 4-year-olds ( Yamaguchi, Kuhlmeier, Wynn, & vanMarle 2009 ). Infants’ interactions at 7 months predict their expressive and productive vocabulary at 14 months ( Lunden & Silven 2011 ). Infants whose mothers show positive responses at 12 months have higher WPPSI IQ at 4 years ( Pearson et al. 2011 ); and fathers’ diverse vocabulary in interactions with their infants at 6 months predicts children’s communication skills at 15 months, after adjusting for infant developmental level at 6 months and other confounders ( Pancsofar & Vernon-Feagans 2010 ). Noll and Harding (2003) found that, when mothers respond to their 12- to 47-month-olds’ object play in an “options-promoting” manner (encouraging, affirming, and/or expanding on the child’s activities), their children later engaged in higher levels of symbolic play. Socially at-risk mothers who received nurse visitations prenatally and postnatally had 15-year-olds who were relatively protected on a host of criminal and antisocial behaviors ( Olds et al 1998 ). Parents who endorse more egalitarian parenting attitudes at 1 month are more likely to have children who are liberal in their ideologies at age 18 years ( Fraley, Griffin, Roisman, & Belsky 2012 ).

Infants’ extrafamilial social experiences are likewise predictive of later development. Infants who experience longer hours of child care, based on average hours/week since 1 month of age, are rated by caregivers at 4.5 years as showing more problem behaviors, even when extensive family covariates and other child care dimensions are included as covariates ( NICHD ECCRN 1998 , 2003a , b ). Infant child care hours continue to predict outcomes through high school, showing modest associations with self-reports of risk taking and impulsivity ( Belsky et al. 2007 ), and the effects of early child care on cognitive and social functioning appear to persist through age 15 ( Vandell et al. 2010 ). Similar patterns of associations between hours of infant care and child problem behaviors have been reported in other studies conducted in the United States ( Loeb et al. 2007 ) as well as Canada ( Côté, Borge, Geoffroy, & Rutter 2008 ) and the United Kingdom ( Neighbourhood Nurseries Initiative Research Team 2007 ).

Reciprocally, clinical levels of maternal depression, when children are between 3 months and 3 years of age, are associated with aggression and antisocial behaviors at 5 to 8 years of age ( Wright, George, Burke, Gelfand, & Teti 2000 ). Indeed, as pointed out earlier, more severe social deprivation in infancy appears to exert untoward effects on later development. Beckett and colleagues (2006) and Kreppner and colleagues (2007) compared multiple cognitive and socioemotional outcomes in 11-year-olds initially reared in Romanian socially depriving institutions but adopted out of Romania into the United Kingdom (U.K.) prior to 2 years of age with comparison samples of noninstitutionalized children adopted from Romania and nondeprived within-U.K. early (before the age of 6 months) adoptees. By the age of 11 years, Romanian children adopted in the U.K. before 6 months of age largely caught up when compared to within-country U.K. adoptees, and more so than Romanian children placed into adoptive homes after 6 months. For example, their mean IQ score at 11 years exceeded 90. Children adopted before 12 months of age are as securely attached as their non-adopted peers, whereas children adopted after their first birthday show less attachment security than non-adopted children ( van den Dries, Juffer, van IJzendoorn, & Bakermans-Kranenburg 2009 ), and the sequelae of deprivation in infancy are still present in some children at age 11, as evidenced in their quasi-autism (problems in social reciprocity and communication, unusual and circumscribed interests), disinhibited attachment (lack of clear differentiation between familiar and unfamiliar adults), inattention/overactivity (both at home and at school, many ADHD diagnoses), and cognitive impairment (poor academic achievement). Sheridan, Fox, Zeanah, McLaughlin, and Nelson (2012) used structural MRI and EEG to examine brain structure and function in typically developing children in Romania exposed to institutional rearing and children previously exposed to institutional rearing but then randomized to a high-quality foster care intervention to evaluate whether placement in an improved environment mitigates the effects of institutional rearing on neural structure. Children with histories of institutional rearing had smaller cortical gray matter volume than never-institutionalized children. Cortical white matter did not differ for children placed in foster care than never-institutionalized children but was smaller for children not randomized to foster care. Other complementary research shows that institutionalized children possess larger amygdalae than noninstitutionalized children ( Tottenham et al. 2010 ).

Within an adopted sample, current executive functioning (EF) is associated with measures of early deprivation after controlling for IQ, with less time spent in the birth family before placement in an institution and lower quality of physical/social care in institutions predicting poorer EF performance ( Hostinar et al. 2012 ).

In Bronfenbrenner’s bioecological model, the macrosystem is acknowledged to exert effects on development ( Bronfenbrenner & Morris 2006 ). Infancy is apparently vulnerable to macrosystem forces. For example, economic conditions in early life (such as business cycles) have far-reaching consequences for individual mortality rates ( van den Berg, Lindeboom, & Lopez 2009 ): Being born during a recession is associated with an increase in the mortality rate after the first year of life. Birth-year (but not subsequent) family income is negatively associated with adult Body Mass Index among low-income families ( Ziol-Guest et al. 2009 ); likewise, immune-mediated chronic diseases play a role in associations between poverty in the prenatal year through age 2 (but not between ages 3 and 5 years or between ages 6 and 15 years) and limitations on activities of daily living, hypertension, and arthritis and on adult productivity between ages 30 and 41 ( Ziol-Guest et al. 2012 ). Duncan et al. (2015) learned that family income in the period age 0 to 2 years had larger beneficial effects on adolescents’ completed schooling and adults’ college attendance than later family income. Generally speaking, economic disadvantage in very early childhood is linked to worse overall health status and higher rates of mortality in adulthood ( Case, Fertig, & Paxson 2005 ), and early family indigence is linked to heightened risk for several chronic diseases in adulthood ( Johnson & Schoeni 2007 as reported in Duncan et al. 2015 ): By age 50, individuals who experienced poverty in early childhood were 46% more likely to have asthma, 75% more likely to be diagnosed with hypertension, 83% more likely to have been diagnosed with diabetes, 2.25 times more likely to have experienced a stroke or heart attack, and 40% more likely to have been diagnosed with heart disease, in comparison to individuals whose family incomes were 200% of the poverty line or greater.

Illustrative Long-Term Longitudinal Epidemiological Projects

The foregoing summaries recount stability and prediction literatures from infancy which have developed around specific topics in specific studies. A number of large-scale multivariate epidemiological longitudinal efforts have also been initiated that have or will adventitiously address issues in stability and prediction from infancy. Among the most notable is the Dutch “hunger winter” study. Near the end of World War II, western (but not northern or eastern) Holland endured a food blockade which provided an unhappy but significant natural experiment in infant development and long-term public health. Unlike other famines, the Dutch Hunger Winter struck during a precisely circumscribed time and place and in a society that keeps comprehensive and meticulous health records of its population. As a result, researchers could identify children who were malnourished during different specific ontogenetic periods and follow their development periodically well into adulthood. Relative to those children who received proper nutrition, malnourished fetuses and infants suffered more nervous system congenital abnormalities as well as increased risk of schizophrenia in maturity ( Hoek, Brown, & Susser 1998 , 1999 ).

Other notable long-term longitudinal multivariate epidemiological investigations from infancy include the Helsinki Birth Cohort 1934-1944 Study in men now reaching old age ( Tuovinen et al. 2012 ); cohorts in the United Kingdom, marked by birthdates of 1946, 1958, 1970, and (the Millennium National Longitudinal Study) 2000, all scheduled to be followed into the later years of life ( Ferri, Bynner, & Wadsworth 2002 ); the National Longitudinal Survey of Youth that has followed a sample of individuals born in the 1950s and 1960s and their offspring ( Blau 1999 ); the Panel Study of Income Dynamics that has followed a nationally representative sample of U.S. children since 1968 ( Duncan et al. 2010 ); the Dunedin Study from New Zealand that has continuously observed children born in 1972–1973; the Carolina Abecedarian Project in the United States that began in the 1970s with predominantly African American families with 3-month-olds; the Cebu Longitudinal Health and Nutrition Survey in the Philippines that began with a cohort of Filipino women who gave birth between 1983 and 1984; the Avon Longitudinal Study of Parents and Children in the United Kingdom that followed all 1991 – 1992 births in that district; and the NICHD SECCYD that recruited families in 1991 from research sites around the United States. Table 1 presents a representative sampling of such studies.

Longitudinal Epidemiological Studies from Infancy to Maturity

General studies are multivariate epidemiological efforts; specific studies are designed to examine a specific topic.

Stability and prediction from infancy are compelling and long-standing topics of philosophical, biological, psychological, and clinical interest. Should we take these emerging long-term stability and predictive validity data from infancy at face value? In evaluating their merit as well as designing the studies of tomorrow and assessing reports that appear in the future, several considerations warrant attention.

Baby biographies of the late 19th and early 20th centuries that followed on Darwin provided a wealth of ideas about infants, and the evidence developed from those baby biographies had two important implications. First, they showed that infants of different ages were competent at different tasks, and, second, they revealed considerable individual variation among infants. The question that naturally arose was whether individual differences on different tasks were transient or consequential. Stability and prediction alike intimate their meaningfulness. Among the perennial and far-reaching questions about human ontogeny, the issue looms large of what connections (if any) obtain between early individual differences and later life.

In practice, stability and prediction effects and their sizes depend on what variables are considered, the way they are measured and when, the length of time between initial and criterion measurements, which analyses are used, which kinds of infants or families living in which circumstances are studied, whether background variables are statistically controlled, and so forth. The penultimate section of this Annual Review explores some of these critical desiderata.

Longitudinal methodology

In the past, cross-sectional designs prevailed in developmental study, and investigations that followed individuals over their lives were rare, essentially excluding longitudinal data. In consequence, life course study has been late arriving to the scholarly developmental literature ( Elder et al. 2015 ). The fortuitous expansion of long-term longitudinal studies, coupled with conceptual and methodological advances, have generated new knowledge about ontogenetic stability and prediction. There is today, moreover, substantial appreciation of the benefits of longitudinal data ( Ferri, Bynner, & Wadsworth 2003 , Hauser 2009 , Phelps, Furstenberg, & Colby 2002 ), which Butz and Torrey (2006) referred to as one of the greatest innovations of 20 th century social science. Even still, most of this growing literature is correlational, and there are far fewer studies that rely on quasi-experimental designs or use rigorous analysis of longitudinal ones.

Cause, source, and covariates

An association between the same characteristic early and late, or between a different early and late characteristics, forges a lagged link which is suggestive but not determinative of a causal connection between the two. Moreover, stability and prediction presuppose, but do not prove, that the stable or predictive characteristic is in the individual. It could be that other endogenous or even exogenous variables theoretically carry or mediate lagged associations.

Stability between infancy and maturity might depend, in part or in whole, on stability in the child’s environment: stability in how significant people interact with the child or in the physical surroundings they provide. For example, one characteristic (easy temperament) at time 1 in infancy could relate to the same or to another characteristic (open personality) at time 2 in maturity because of stability in the individual characteristic or because some environmental characteristic (parents who support well-being) is stable. Individuals inherit a species-typical genome and a species-typical environment. Species-universal conditions constrain development – they limit the contexts in which genes will be expressed – and thus an individual’s life course. For the most part naturalistic circumstances favor environmental stability, and children are reared in stable material and social environments ( Holden & Miller 1999 ), so that consistent experiences across (at least) early development are likely. For example, observer ratings of maternal sensitivity in parent–child relationships correlate across multiple assessment waves ranging from early infancy to age 15 ( Fraley, Roisman, & Haltigan 2012 ). The likelihood of stability and predictive validity is enhanced when environmental contexts remain relatively stable. Of importance to the interpretation of stability and prediction, beyond temporal ordering, is therefore the control of continuing environmental supports to stability and prediction.

Similarly, inclusion and elimination of other third variable common causes that could mediate observed links is requisite to apt interpretation. If third variables mediate stability or prediction, once the contribution of the common cause is removed, individual stability or prediction should attenuate. For this reason, third variables are increasingly being taken into account through the application of partial correlations ( Lozoff, Jimenez, & Wolf 1991 ), hierarchical regression approaches ( Rose-Jacobs et al. 2009 ), or other statistical maneuvers. Path analysis modeling makes it possible to reduce the influence of key confounds and initial covariances, as it allows control for spurious effects related to covariances between infant and other exogenous factors. Structural equation modeling is often also employed to assess stabilities and predictions controlling for other variables, and here the use of latent variables capitalizes on the shared contributions of different approaches, allows for measurement of a characteristic to vary (appropriately) across time while retaining comparability, and permits purer representations of characteristics because variance arising from sources unique to particular indicators that is not accounted for by the factor is relegated to its error term ( Bentler 1995 , Bentler & Wu 1995 , Bollen 1989 , Kline, 1998 ).

Prediction failures

Bell, Taylor, and Dockrell (1965) examined relations between low birth weight and incidence of disease or deformity at 10 years; they found no relation. Kagan, Lapidus, and Moore (1978) showed 2-year-olds distinctive and unusual pictures which they failed to recognize as 10-year-olds. Some studies produce mixed or inconclusive stability or prediction. In essence, it could be that there actually is little or no stability or prediction from infancy. However, it would be invalid to accept this null hypothesis about human development before examining measures that redress a raft of alternative explanations for null results. The want of a connection between a characteristic in infancy and later life could be attributable to several different possibilities (such as the measurement instrument or the measure) or correlations may be misleading (if development follows a progression of discrete stages) or if the range of scores at either anchor age is truncated ( Smolak & Levine 1984 ) or if the experience is brief, unimportant or not meaningful ( Kagan 2013 ).

Of course, some development may seem discontinuous. New abilities emerge that often qualitatively differ from anything preceding. Do all early attainments qualify as precursors to later ones? Are nonverbal gestures precursors to language? Is the newborn stepping reflex a precursor to walking?

Moreover, there are many reasons to expect null or small associations between infancy and maturity. One reason is that individual differences in maturity are influenced by concurrent experiences. For example, daily-diary study indicates that variation in adult attachment patterns reflects contemporaneous experiences in interpersonal relationships ( La Guardia, Ryan, Couchman, & Deci 2000 , Pierce & Lydon 2001 ). The likelihood that early status or experience plays a role in shaping later individual differences has to be judged in the context of understanding that later variance can result from more proximate cause. Likewise, environments are subject to change. Furthermore, all mature characteristics are likely a function of a number of factors. To the extent that multiple factors contribute to variation in the mature phenotype, the explanatory power of any one relative to the rest is diminished ( Ahadi & Diener 1989 , Strube, 1991 ).

IVs and DVs

Stability and prediction depend crucially on the infant variable, the criterion variable, and the fit between the two. This admonition has several constituents. First, to be valuable and meaningful, a characteristic observed in an infant needs to be reliable, meaning that observed one day it ought to be similar how it is that observed in the same infant a short time later. Otherwise, the characteristic would not constitute a reliable index of the infant. Statistically speaking, as Spearman noted, unreliability places inexorable limits on predictive validity ( Cohen, Cohen, West, & Aiken 2003 ). (Similarly, it is unreasonable to expect an early experience to predict later to a greater degree than it predicts subsequent assessments of itself.) Additionally, a characteristic may not be stable at one point in the life course, but stabilize at a later age.

Second, use of a single IV may underestimate the true effect on a mature criterion. Generally, the less information that is available, the lower the stability estimate ( Hartmann et al. 2011 ). Colombo ( Colombo, Mitchell, & Horowitz 1988 , Colombo, Shaddy, Richman, Maikranz, & Blaga 2004 ) showed that the predictive validity of infant performance is improved by combining or aggregating items or tasks. Because the effects of individual differences can be expected to accumulate across development, focus on a single predictive index measured at a single point in time may underestimate its true contribution. Focus on a single outcome variable measured at a single point in time may likewise underestimate stability and prediction in development ( Caspi, Bem, & Elder 1989 , Rutter & Rutter 1993 ).

In considering IVs, third, it may be critical to distinguish between performance and competence, because one may predict better than the other. Relatively rapid development also makes it difficult to determine which performance is more representative of the baby and therefore predictive: optimal performance, average performance, or minimal performance.

Last, across time the same measures (that assess homotypic stability) are (usually) more highly related than are different measures (that assess heterotypic stability or prediction). Thus, homotypic stability may represent liberal (upper bound) estimates which are augmented because of shared source and method variance, practice effects, and the like, whereas heterotypic stability may represent conservative (lower bound) estimates because of the variance introduced by differences in assessment instruments and procedures used at different times. Greater stability might be expected between variables that conceptually relate than between those which do not. (Similarly, whether assessments are made across consistent or inconsistent contexts may make a difference: the former enhance stability and the latter attenuate stability; Bornstein, Tamis-LeMonda, & Haynes 1999 .) Finally, although surface manifestations of characteristics change over the life course, some latent variable of surface variables might reflect an enduring individual difference ( Bornstein & Putnick 2012 ).

Different patterns of stability and prediction could emerge depending on the ages at which individuals are initially and terminally assessed, and concomitantly longitudinal effects are a complex function of the interval between assessments. Measures taken early in development are (usually) less highly predictive than are measures taken later in development ( Asendorpf 1992 , McGrew & Knopik 1993 ), as people are thought to become increasingly consistent in relation to one another as they age ( Roberts & DelVecchio 2000 ), and so stabilities tend to increase with increasing age. Furthermore, the shorter the inter-assessment interval, normally the higher the stability estimate, a phenomenon sometimes called the Guttman (1954) “simplex” ( Conley 1984 ).

Both catch-up and sleeper effects moderate stability and prediction. Catch-up effects define situations where a relation between time 1 and time 2 may hold, but not between time 1 and time 3 ( Wilson 1978 ). For example, compared to infants born at term very low birth weight infants show deficits in reading comprehension at 9 years that no longer obtain at 15 years ( Samuelsson et al. 2006 ). Reciprocally, sleeper effects define situations where a relation between time 1 and time 2 may not hold, but may emerge between time 1 and time 3 ( Betancourt et al. 2011 , Bridgett & Mayes 2011 ). For example, infants who were born during the Dutch hunger winter and experienced chronic malnutrition in their first trimester in utero manifest elevated rates of schizophrenia, which did not emerge until late in development ( Hoek et al. 1999 , Roseboom, de Rooij, & Painter 2006 ).

Developmental research has primarily focused attention on micro timescales to assess normative ontogenetic patterning. Less attention has been focused on longer timescales to explore stability and prediction, and even less has been done to explore development in terms of very long timescales (our concern here). Comprehensive explanations in development need to consider all timescale perspectives.

Sample size and composition moderate stability and prediction. Small samples may lack the power to detect existing associations that large samples possess. Homogenous samples may harbor associations that are masked by diverse samples ( Bornstein, Jager, & Putnick 2013 ). In some subsamples stability and prediction may be smaller, in other subsamples larger. Loss of follow-up over time (attrition) may introduce bias, as stability and prediction apply only to those individuals who survive longitudinal study.

Effect size

Effect size (like the correlation coefficient which is often the main statistic used to authenticate the relation between infant scores and mature scores) quantifies stability or prediction. Stability and prediction effect sizes tend to be small to modest. However, judgments of the importance of an effect are subjective. As many theoreticians and empiricists have emphasized, small effect sizes can be meaningful, as for example from a public health perspective ( Abelson 1985 , Ahadi & Diener 1989 , Cortina & Landis 2009 , Prentice & Miller 1992 , Rosenthal & Rubin 1982 , 1983 , Vacha-Haase & Thompson 2004 , Yeaton & Sechrest 1981 ). The correlation coefficient, moreover, is subject to the nature of the distribution and does not necessarily provide useful information about individual cases. Lack of heterogeneity in the distribution of scores (restriction of range) at either anchor age can attenuate correlation, and failure to examine individual patterns may account for the apparent lack of stability or predictability.

Stability and prediction need to be interpreted taking into consideration assumptions of a field. Background theory, classical research, and even the temporal distance of the relation can create a situation in which any non-zero effect reasonably supports conclusions about stability and prediction. That is, importance is at least partly a function of whether stability or prediction is expected at all. Theory and empiricism once established the strong expectation of no stability or predictive validity of mental development from infancy ( Bayley 1949 ), and the implications of this position were far-reaching for the nature of infancy and conceptions of mental development. To be meaningful new predictive data may need only fail to disconfirm such expectations. In the field of stability and prediction from infancy, small effects can represent impressive support, and showing that stability or prediction holds under unlikely and unexpected circumstances can be as striking as (or, in some cases, more striking than) showing that one or the other accounts for a great deal of variance. The fact that an effect survives a stringent test, as in the inclusion of multiple controls, is additionally probative.

Direct and Indirect Effects

Some stability or prediction effects are direct, others indirect. Direct effects may be evidenced by associations between IVs and DVs. Indirect effects play theoretically appealing and essential roles, as in developmental cascades, but may be more elusive and challenging to detect than direct effects. They are also destined to be small mathematically due to the statistical fact that, as the number of intervening variables in an indirect effect increases, the magnitude of the overall indirect effect decreases. (The indirect effect is the product of path coefficients leading from an independent variable through intervening variable(s) to a criterion variable.)

Weaknesses and Strengths of the Literature

On the one hand, longitudinal study is subject to design flaws. Reusing the same measures, a good thing for strict assessments of stability, can capitalize on practice effects and shared method variance, a bad thing re conclusions. Similarly, the use of the same reporters or testers at different ages capitalizes on shared source variance that may inflate stability correlations, and staff who are familiar with participants may carry over their familiarity from one testing session to another. Most stability and prediction reports do not indicate whether testers are masked (but see Rose-Jacobs et al. 2004 , Rose-Jacobs et al. 2011 ). On the other hand, the stability and prediction literature doubtlessly suffers the “file drawer” problem, it being unlikely that nonsignificant findings have been published ( Rosenthal 1979 ).

Considerations of stability and prediction often do not speak to the specific mechanisms through which each occurs, but they should. The assessment and demonstration stability or prediction constitute the (important) descriptive phase of investigation, and either may obtain even if specific developmental processes remain unspecified. However, clarifying mechanisms of stability and prediction will constitute an important next wave in future research. Ultimate criteria for success in developmental science turn on how well we can explain and understand processes underlying individual functioning and development and on how well we can predict.

On first observation, newborns and infants often appear disorganized and erratic. At a given moment, babies seem to be constantly moving their eyes, hands, and feet without apparent purpose. Over longer periods, they appear to shift randomly and unpredictably between sleep and alertness. However, infants are not quite so irregular and unpredictable. Close and consistent inspection reveals that infants are regular in many ways and their systems cycle in detectable patterns. Indeed, infant activity is organized at fast, medium, and slow rhythms. Some actions regularly cycle at high frequencies, perhaps once or more every second. Heartbeats, breathing, and sucking exemplify fast biological rhythms that maintain life, and kicking and rocking illustrate other fast-cycling behaviors. General movements of the body cycle at intermediate rates, on the order of once every minute or two. States of waking, quiet sleep, and active sleep cycle at low frequencies in periods of up to 24 hours. By observing activity over extended times and carefully decomposing it, it is possible to detect regularity underlying infants’ seeming randomness. A snapshot of the infant at any one time captures the simultaneous and independent cycling of several complex rhythms. In short, apparent irregularity is only just that, apparent, and much infant behavior is characterized by underlying regularity.

Macken and Burton (1979) wished to know how infants acquire the voicing contrast in American English word-initial stop consonants, and so they recorded the speech of four monolingual children at 2-week intervals, beginning in infancy. They then submitted recordings of infants’ spontaneous speech to two kinds of analyses: transcriptions by trained phoneticians and instrumental analysis. The human judges divided infant data into three general stages: (1) the child has no contrast; (2) the child has a contrast but one that falls within the adult perceptual boundaries and thus is presumably not perceptible to adults; and (3) the child has a contrast that resembles the adult contrast. Some Stage 2 contrasts which children maintained went unnoted by the transcribers and were presumably not perceptible to adults. However, spectrograms with high temporal resolution and scale magnification revealed a statistically significant number of distinct phonemically voiceless stop productions. In short, judgments of adults did not capture significant facts about the child’s language production where spectrographic analysis provided insight. Speech contrasts that infants had learned and were maintaining would not have been detected by parents or other adults, and it might have taken up to another year before the children’s productions improved to the point where the contrasts that the infants were making were perceived by adults. These two homilies impart pointed lessons for understanding stability and prediction from infancy. Not the least, methods and measures applied today that fail to substantiate preservation in development leave open the possibility that methods and measures applied tomorrow may reverse current conclusions.

Development is governed by genetic and biological factors in combination with experiences and environmental influences. Thus, developmental stability and prediction of any characteristic are attributable to endogenous factors that transact exogenous ones. Biological forces generally tend to reinforce homeostasis in the individual. Moreover, the consistent social network in which development normally transpires also contributes to stability and prediction. Thus, individual ←→ environmental relational processes actually tilt to promote stability and prediction in development. Contrary to first blush, stability and prediction in development are expectable.

That said, even the strongest stability or prediction coefficient one could practicably expect to see, say r = .90, leaves substantial common variance unaccounted for, ≈20%. Here, theoretical perspective comes into play. Focusing on instability and prediction failures would lead to the singular but limited view that development is disorderly; focusing on stability and prediction risks overlooking necessary adaptability and change in the developing organism. Despite stability and prediction, children can and do alter over time in their status relative to one another. The life-span perspective in developmental science specifies that human beings are open systems, and the plastic nature of psychological functioning ensures both stability and instability across the life course. Both confer advantage. Many developmental processes are Janus-like with both stable and unstable, continuous and discontinuous aspects. Infant status does not fix a child’s health or height, perceptiveness or personality. To be stable or predictable does not mean to be immutable or impervious to experience or adaptation. Like stability, adoption is an identifying characteristic of development, and children change in both their relative standing and mean level on every characteristic as they grow.

The mature status of each aspect of a person is influenced by contemporary circumstances and by expectations of the future, but it is also affected by prenatal and infancy status and experiences and, in some instances, by circumstances of prior generations ( Elder et al. 2015 ). Interdisciplinary life-course study, coupled with the arrival of long-term longitudinal research, is occupying increasing attention, as the precursors to mature status are explored among early sensitive periods, cascades, cumulative effects, and other temporal associations that extend over decades ( Bauldry, Shanahan, Boardman, Miech, & Macmillan 2012 , Bornstein 1989 , Kuh & Ben-Schlomo 2004 ).

Long-term studies of stability and prediction are identifying relations between late-life adaptation and the earliest phases of life-span development. Although this Annual Review has documented links between early and later life, those links require reinforcement as much as reassessment, and there is much more to learn. Important efforts should start with refinement, replication, and reflection.

CONCLUSIONS

…The childhood shews the man … -- John Milton (1671) , Paradise Regained , Book 4, line 220

A key goal of contemporary developmental science is mapping temporal trajectories from early characteristics to mature phenotypes. Many developmentalists have maintained that different stages of life vary qualitatively, that infancy stands apart from the balance of the life course, and that development from infancy is unstable and noncontinuous. However, the “blooming, buzzing confusion” of infancy cloaks order. Some relations between infancy and maturity may be obscured because they are displaced in time, and others may go unnoticed because surface manifestations of different characteristics at different developmental periods appear unrelated. We now know too that much of development consists of hierarchically organized abilities that subsume one another. An implication of contemporary relational systems perspectives is that earlier emerging characteristics in development lay foundations for and so likely exert impact on later appearing characteristics.

A central issue in developmental study is evaluation of forces bound up in ontogenetic advance. Central to understanding developmental advance is recognizing the contributions of the individual, experience, and their transactions. Individuals contribute to their own development, and we are increasingly aware that people are agents in their own lives. The emerging literature in stability and prediction indicates that infants bring substantial variation in their individuality to their own long-term development.

Stability and predictive validity in development from infancy have several noteworthy implications. First, they have meaning for developmental science in terms of more adequately describing the growth of individuals. Second, they have implications for more completely understanding the nature of diverse biological and psychological phenomena. Through elucidation of stability and prediction, infancy studies can lead to insights that have significance for psychology as a whole. Studies of stability and prediction between infancy and maturity are therefore important to theory building; they are equally important to understanding clinical populations. Because there are threads of stability and prediction from infancy, third, measures in infancy might one day serve as screening tools for early detection of later (risk) status and so infancy has implications for the identification, prevention, and treatment of disorders. The emerging critical mass of data on stability and prediction overturn the argument that infancy is not meaningful in itself and that it is unrelated to later life. Early childhood exposure to microorganisms that are common in the natural environment adjusts the immune system so that even disadvantaged adults living under unhealthy conditions in low and middle income countries have lower blood concentrations of proteins that signal inflammations that portend cancer, diabetes, and heart disease ( McDade 2012 ). The contemporary life-course perspective on human development supports some stability and prediction, even from the prenatal period.

The developmental changes that take place during the first year of life are as or more dramatic than any others in the human lifespan. The most remarkable involve the changing shape and capacity of the body, the complexity of the nervous system, the dawning of sensory and perceptual capacities, the increasing abilities to make sense of, understand, and master things in the world, the achievement of communication, the emergence of characteristic personal styles, and the formation of specific social bonds. At no other time is development so fast-paced or thoroughgoing in so many different spheres of life. Yet, at the core of the infant, and later the toddler, child, adolescent, and adult, is the same individual, and some stability and predictability from infancy – whatever their dynamic endogenous and exogenous origins – is expectable.

Deconstructing infancy studies in this way contributes to elaborating and to explaining infancy qua a dimension of human fascination and intellectual significance. The ineffable romance of infancy may haunt us in many ways, but in other ways we now see more clearly that infancy contributes concretely to our understanding ourselves. The fact that infants are unvolitional, uncooperative, unstable, nonverbal, and motorically inept once warded off all but philosophical speculation about them. Developmental scientists have finally overcome infants’ formidable and intractable posture to extract information of all sorts from and about them. In recent years, a revolution has taken place in infancy studies, fueled by technological and methodological advances. We now know a great deal about babies’ perceptions, thoughts, and feelings. Taken together, longitudinal studies are coming to bind infancy more tightly to the tapestry of life span development. Longitudinality is a social science Hubble telescope ( Butz & Torrey 2006 ).

Infancy is the first phase of life lived outside the womb, and the characteristics developed and acquired then help to forge a foundation for the balance of the life course; some individual differences in infancy may endure, at least in part, and they are certainly those that later experiences build on or modify. Infancy is only one phase in the lifespan, however, and so our physical development, nervous system maturity, motor capacities, perceptual abilities, cognitive competencies, and personalities and social styles are also shaped by development and experiences after infancy. Living is to experience consequential and life-altering events. The start does not fix the course or outcome of development, but it clearly exerts an impact on both. Ascribing certain prospects to the future may be unachievable, but the longitudinal literature from infancy is starting to reveal enduring effects that we should not ignore or dismiss. The future may not be an utterly random bet. “ At first the infant …” Shakespeare has Jacques recite in As You Like It . Infancy introduces the part and also sets the stage for the unfolding drama that is to follow.

Acknowledgments

Supported by the Intramural Research Program of the NIH, NICHD. I thank A. Dovidio, H. Simon, and D. L. Putnick.

DISCLOSURE STATEMENT

The author is not aware of any affiliations, memberships, funding, or financial affiliations that might be perceived as affecting the objectivity of this review.

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• Case report
• Open access
• Published: 11 September 2017

A case of a four-year-old child adopted at eight months with unusual mood patterns and significant polypharmacy

• Magdalena Romanowicz   ORCID: orcid.org/0000-0002-4916-0625 1 ,
• Alastair J. McKean 1 &
• Jennifer Vande Voort 1  

BMC Psychiatry volume  17 , Article number:  330 ( 2017 ) Cite this article

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Long-term effects of neglect in early life are still widely unknown. Diversity of outcomes can be explained by differences in genetic risk, epigenetics, prenatal factors, exposure to stress and/or substances, and parent-child interactions. Very common sub-threshold presentations of children with history of early trauma are challenging not only to diagnose but also in treatment.

Case presentation

A Caucasian 4-year-old, adopted at 8 months, male patient with early history of neglect presented to pediatrician with symptoms of behavioral dyscontrol, emotional dysregulation, anxiety, hyperactivity and inattention, obsessions with food, and attachment issues. He was subsequently seen by two different child psychiatrists. Pharmacotherapy treatment attempted included guanfacine, fluoxetine and amphetamine salts as well as quetiapine, aripiprazole and thioridazine without much improvement. Risperidone initiated by primary care seemed to help with his symptoms of dyscontrol initially but later the dose had to be escalated to 6 mg total for the same result. After an episode of significant aggression, the patient was admitted to inpatient child psychiatric unit for stabilization and taper of the medicine.

Conclusions

The case illustrates difficulties in management of children with early history of neglect. A particular danger in this patient population is polypharmacy, which is often used to manage transdiagnostic symptoms that significantly impacts functioning with long term consequences.

Peer Review reports

There is a paucity of studies that address long-term effects of deprivation, trauma and neglect in early life, with what little data is available coming from institutionalized children [ 1 ]. Rutter [ 2 ], who studied formerly-institutionalized Romanian children adopted into UK families, found that this group exhibited prominent attachment disturbances, attention-deficit/hyperactivity disorder (ADHD), quasi-autistic features and cognitive delays. Interestingly, no other increases in psychopathology were noted [ 2 ].

Even more challenging to properly diagnose and treat are so called sub-threshold presentations of children with histories of early trauma [ 3 ]. Pincus, McQueen, & Elinson [ 4 ] described a group of children who presented with a combination of co-morbid symptoms of various diagnoses such as conduct disorder, ADHD, post-traumatic stress disorder (PTSD), depression and anxiety. As per Shankman et al. [ 5 ], these patients may escalate to fulfill the criteria for these disorders. The lack of proper diagnosis imposes significant challenges in terms of management [ 3 ].

J is a 4-year-old adopted Caucasian male who at the age of 2 years and 4 months was brought by his adoptive mother to primary care with symptoms of behavioral dyscontrol, emotional dysregulation, anxiety, hyperactivity and inattention, obsessions with food, and attachment issues. J was given diagnoses of reactive attachment disorder (RAD) and ADHD. No medications were recommended at that time and a referral was made for behavioral therapy.

She subsequently took him to two different child psychiatrists who diagnosed disruptive mood dysregulation disorder (DMDD), PTSD, anxiety and a mood disorder. To help with mood and inattention symptoms, guanfacine, fluoxetine, methylphenidate and amphetamine salts were all prescribed without significant improvement. Later quetiapine, aripiprazole and thioridazine were tried consecutively without behavioral improvement (please see Table  1 for details).

No significant drug/substance interactions were noted (Table 1 ). There were no concerns regarding adherence and serum drug concentrations were not ordered. On review of patient’s history of medication trials guanfacine and methylphenidate seemed to have no effect on J’s hyperactive and impulsive behavior as well as his lack of focus. Amphetamine salts that were initiated during hospitalization were stopped by the patient’s mother due to significant increase in aggressive behaviors and irritability. Aripiprazole was tried for a brief period of time and seemed to have no effect. Quetiapine was initially helpful at 150 mg (50 mg three times a day), unfortunately its effects wore off quickly and increase in dose to 300 mg (100 mg three times a day) did not seem to make a difference. Fluoxetine that was tried for anxiety did not seem to improve the behaviors and was stopped after less than a month on mother’s request.

J’s condition continued to deteriorate and his primary care provider started risperidone. While initially helpful, escalating doses were required until he was on 6 mg daily. In spite of this treatment, J attempted to stab a girl at preschool with scissors necessitating emergent evaluation, whereupon he was admitted to inpatient care for safety and observation. Risperidone was discontinued and J was referred to outpatient psychiatry for continuing medical monitoring and therapy.

Little is known about J’s early history. There is suspicion that his mother was neglectful with feeding and frequently left him crying, unattended or with strangers. He was taken away from his mother’s care at 7 months due to neglect and placed with his aunt. After 1 month, his aunt declined to collect him from daycare, deciding she was unable to manage him. The owner of the daycare called Child Services and offered to care for J, eventually becoming his present adoptive parent.

J was a very needy baby who would wake screaming and was hard to console. More recently he wakes in the mornings anxious and agitated. He is often indiscriminate and inappropriate interpersonally, unable to play with other children. When in significant distress he regresses, and behaves as a cat, meowing and scratching the floor. Though J bonded with his adoptive mother well and was able to express affection towards her, his affection is frequently indiscriminate and he rarely shows any signs of separation anxiety.

At the age of 2 years and 8 months there was a suspicion for speech delay and J was evaluated by a speech pathologist who concluded that J was exhibiting speech and language skills that were solidly in the average range for age, with developmental speech errors that should be monitored over time. They did not think that issues with communication contributed significantly to his behavioral difficulties. Assessment of intellectual functioning was performed at the age of 2 years and 5 months by a special education teacher. Based on Bailey Infant and Toddler Development Scale, fine and gross motor, cognitive and social communication were all within normal range.

J’s adoptive mother and in-home therapist expressed significant concerns in regards to his appetite. She reports that J’s biological father would come and visit him infrequently, but always with food and sweets. J often eats to the point of throwing up and there have been occasions where he has eaten his own vomit and dog feces. Mother noticed there is an association between his mood and eating behaviors. J’s episodes of insatiable and indiscriminate hunger frequently co-occur with increased energy, diminished need for sleep, and increased speech. This typically lasts a few days to a week and is followed by a period of reduced appetite, low energy, hypersomnia, tearfulness, sadness, rocking behavior and slurred speech. Those episodes last for one to 3 days. Additionally, there are times when his symptomatology seems to be more manageable with fewer outbursts and less difficulty regarding food behaviors.

J’s family history is poorly understood, with his biological mother having a personality disorder and ADHD, and a biological father with substance abuse. Both maternally and paternally there is concern for bipolar disorder.

J has a clear history of disrupted attachment. He is somewhat indiscriminate in his relationship to strangers and struggles with impulsivity, aggression, sleep and feeding issues. In addition to early life neglect and possible trauma, J has a strong family history of psychiatric illness. His mood, anxiety and sleep issues might suggest underlying PTSD. His prominent hyperactivity could be due to trauma or related to ADHD. With his history of neglect, indiscrimination towards strangers, mood liability, attention difficulties, and heightened emotional state, the possibility of Disinhibited Social Engagement Disorder (DSED) is likely. J’s prominent mood lability, irritability and family history of bipolar disorder, are concerning for what future mood diagnosis this portends.

As evidenced above, J presents as a diagnostic conundrum suffering from a combination of transdiagnostic symptoms that broadly impact his functioning. Unfortunately, although various diagnoses such as ADHD, PTSD, Depression, DMDD or DSED may be entertained, the patient does not fall neatly into any of the categories.

This is a case report that describes a diagnostic conundrum in a young boy with prominent early life deprivation who presented with multidimensional symptoms managed with polypharmacy.

A sub-threshold presentation in this patient partially explains difficulties with diagnosis. There is no doubt that negative effects of early childhood deprivation had significant impact on developmental outcomes in this patient, but the mechanisms that could explain the associations are still widely unknown. Significant family history of mental illness also predisposes him to early challenges. The clinical picture is further complicated by the potential dynamic factors that could explain some of the patient’s behaviors. Careful examination of J’s early life history would suggest such a pattern of being able to engage with his biological caregivers, being given food, being tended to; followed by periods of neglect where he would withdraw, regress and engage in rocking as a self-soothing behavior. His adoptive mother observed that visitations with his biological father were accompanied by being given a lot of food. It is also possible that when he was under the care of his biological mother, he was either attended to with access to food or neglected, left hungry and screaming for hours.

The current healthcare model, being centered on obtaining accurate diagnosis, poses difficulties for treatment in these patients. Given the complicated transdiagnostic symptomatology, clear guidelines surrounding treatment are unavailable. To date, there have been no psychopharmacological intervention trials for attachment issues. In patients with disordered attachment, pharmacologic treatment is typically focused on co-morbid disorders, even with sub-threshold presentations, with the goal of symptom reduction [ 6 ]. A study by dosReis [ 7 ] found that psychotropic usage in community foster care patients ranged from 14% to 30%, going to 67% in therapeutic foster care and as high as 77% in group homes. Another study by Breland-Noble [ 8 ] showed that many children receive more than one psychotropic medication, with 22% using two medications from the same class.

It is important to note that our patient received four different neuroleptic medications (quetiapine, aripiprazole, risperidone and thioridazine) for disruptive behaviors and impulsivity at a very young age. Olfson et al. [ 9 ] noted that between 1999 and 2007 there has been a significant increase in the use of neuroleptics for very young children who present with difficult behaviors. A preliminary study by Ercan et al. [ 10 ] showed promising results with the use of risperidone in preschool children with behavioral dyscontrol. Review by Memarzia et al. [ 11 ] suggested that risperidone decreased behavioral problems and improved cognitive-motor functions in preschoolers. The study also raised concerns in regards to side effects from neuroleptic medications in such a vulnerable patient population. Younger children seemed to be much more susceptible to side effects in comparison to older children and adults with weight gain being the most common. Weight gain associated with risperidone was most pronounced in pre-adolescents (Safer) [ 12 ]. Quetiapine and aripiprazole were also associated with higher rates of weight gain (Correll et al.) [ 13 ].

Pharmacokinetics of medications is difficult to assess in very young children with ongoing development of the liver and the kidneys. It has been observed that psychotropic medications in children have shorter half-lives (Kearns et al.) [ 14 ], which would require use of higher doses for body weight in comparison to adults for same plasma level. Unfortunately, that in turn significantly increases the likelihood and severity of potential side effects.

There is also a question on effects of early exposure to antipsychotics on neurodevelopment. In particular in the first 3 years of life there are many changes in developing brains, such as increase in synaptic density, pruning and increase in neuronal myelination to list just a few [ 11 ]. Unfortunately at this point in time there is a significant paucity of data that would allow drawing any conclusions.

Our case report presents a preschool patient with history of adoption, early life abuse and neglect who exhibited significant behavioral challenges and was treated with various psychotropic medications with limited results. It is important to emphasize that subthreshold presentation and poor diagnostic clarity leads to dangerous and excessive medication regimens that, as evidenced above is fairly common in this patient population.

Neglect and/or abuse experienced early in life is a risk factor for mental health problems even after adoption. Differences in genetic risk, epigenetics, prenatal factors (e.g., malnutrition or poor nutrition), exposure to stress and/or substances, and parent-child interactions may explain the diversity of outcomes among these individuals, both in terms of mood and behavioral patterns [ 15 , 16 , 17 ]. Considering that these children often present with significant functional impairment and a wide variety of symptoms, further studies are needed regarding diagnosis and treatment.

Abbreviations

Attention-Deficit/Hyperactivity Disorder

Disruptive Mood Dysregulation Disorder

Disinhibited Social Engagement Disorder

Post-Traumatic Stress Disorder

Reactive Attachment disorder

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We are also grateful to patient’s legal guardian for their support in writing this manuscript.

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MR, AJM, JVV conceptualized and followed up the patient. MR, AJM, JVV did literature survey and wrote the report and took part in the scientific discussion and in finalizing the manuscript. All the authors read and approved the final document.

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Correspondence to Magdalena Romanowicz .

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Romanowicz, M., McKean, A.J. & Vande Voort, J. A case of a four-year-old child adopted at eight months with unusual mood patterns and significant polypharmacy. BMC Psychiatry 17 , 330 (2017). https://doi.org/10.1186/s12888-017-1492-y

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Quality Assessment

Analysis and reporting, flow of studies and study characteristics, quality of studies, associations between neonatal stress and clinical outcomes, associations between neonatal stress and laboratory and imaging outcomes, strengths and limitations, implications, conclusions, acknowledgments, neonatal stress, health, and development in preterms: a systematic review.

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Nienke H. van Dokkum , Marlou L.A. de Kroon , Sijmen A. Reijneveld , Arend F. Bos; Neonatal Stress, Health, and Development in Preterms: A Systematic Review. Pediatrics October 2021; 148 (4): e2021050414. 10.1542/peds.2021-050414

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An overview of the full range of neonatal stressors and the associated clinical, laboratory, and imaging outcomes regarding infants’ health and development may contribute to the improvement of neonatal care.

To systematically review existing literature on the associations between all kinds of neonatal stressors and the health and development of preterm infants.

Data sources included Embase, Medline, PsycINFO, the Cumulative Index to Nursing and Allied Health Literature, and reference lists.

Studies were eligible if they included a measure of neonatal stress during the NICU stay, reported clinical, laboratory, and/or imaging outcomes regarding health and/or development on discharge from the NICU or thereafter, included preterm infants, and were written in English or Dutch.

Two reviewers independently screened the sources and extracted data on health and development. Study quality was assessed by using the Newcastle-Ottawa Quality Assessment Scale.

We identified 20 articles that reported on neonatal stress associated negatively with clinical outcomes, including cognitive, motor, and emotional development, and laboratory and imaging outcomes, including epigenetic alterations, hypothalamic-pituitary-adrenal axis functioning, and structural brain development. We found no evidence regarding associations with growth, cardiovascular health, parent-infant interaction, the neonatal immune system, and the neonatal microbiome.

The studies were all observational and used different definitions of neonatal stress.

Neonatal stress has a profound impact on the health and development of preterm infants, and physicians involved in their treatment and follow-up should be aware of this fact.

During their stay in a NICU, preterm infants (gestational age of <37 weeks) are exposed to a variety of potential stressors. These stressors include noise and bright lights, medical interventions, and skin-breaking procedures, but routine handling by physicians and nursing staff and maternal separation also constitute stress. 1   Regarding painful skin-breaking procedures, for example, averages of 7.5 to 17.1 per day have been reported. 2   Because these procedures are known to elicit obvious pain responses, they have been studied most often. Other, perhaps less obvious stressors, such as handling by medical staff, maternal separation, and environmental stress, evoke similar responses 3   (a phenomenon known as sensitization 4   ), adding to the extensive range of neonatal stress. All procedures experienced by preterm infants during their stay in a NICU should therefore be taken into consideration. For the purpose of this study, we defined stress as “an adverse circumstance that disturbs, or is likely to disturb, the normal physiological or psychological functioning of an individual,” thereby basing ourselves on the definition given by the Oxford English Dictionary. 5   Although a few overviews of literature on the topic of neonatal stress exist, 4 , 6   to date, a comprehensive systematic literature review on the broad range of neonatal stressors, which extends beyond skin-breaking procedures, is lacking.

The environment of the NICU, and the stress associated with it, is thought to have major long-lasting effects on neonatal health and development. 7   These effects may include poorer clinical outcomes on cognitive, psychomotor, and emotional and behavioral development, all representing domains in which preterm children run a higher risk of impairment. 8 – 12   Effects may also include laboratory and imaging findings because these may reflect pathways between stressors and concurrent or later clinical outcomes. First, for example, the hypothalamic-pituitary-adrenal (HPA) axis, which is responsible for the production of glucocorticoids, including cortisol (dubbed the “stress hormone”), is likely to be involved in shaping reactions to neonatal stress. 4   Second, evidence emerging rapidly from the field of behavioral epigenetics is that epigenetic alterations (changes to the DNA profile without changing the nucleotide sequence) may play a role in development. 13   Third, the role of the neuroendocrine system and microbiome is receiving increasing attention, especially in the field of psychiatry. This discipline associates early life experiences with proinflammatory immune profiles, changes to the gut-brain axis, and psychiatric disorders, such as anxiety, depression, or dementia. 14 , 15   Finally, imaging studies show that the preterm brain develops differently from that of term infants 16 , 17   because synaptic connections are being formed and cortical networks are being established during this period. 18  

An overview of literature on the associations between neonatal stress in the broad sense, as outlined here, and various health and developmental outcomes is important because it may well contribute to improvement of neonatal care. 4 , 7   We therefore aimed to systematically review the literature dealing with the assessment of associations between all kinds of neonatal stress and clinical, laboratory, and imaging outcomes in the domains of health and development of preterm infants.

We performed our search strategy according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for systematic reviews. 19   We used Endnote X8 as a reference manager. Two researchers (N.H.v.D and M.L.A.d.K.) conducted the independent systematic searches in the Embase, Medline, PsycINFO, and the Cumulative Index to Nursing and Allied Health Literature databases for all literature up to and including April 2021. In addition, the same 2 authors independently screened the reference lists of all the retrieved articles for potential inclusion of relevant publications.

Our search comprised 3 main elements: (1) stress, (2) preterm birth, and (3) clinical, laboratory, and imaging outcomes of health and development. Regarding the element stress, we included all kinds of stress neonates might experience during their NICU stay, such as pain-related (skin-breaking) procedures, nursing and handling, noise and light, and maternal separation. We did not include studies that measured an immediate reaction to neonatal stress because our interest lay in collective circumstances during the NICU stay. Regarding the element preterm birth, we included studies with infants born at a gestational age of <37 weeks with or without a term control group. Regarding the element outcomes of health and development, we first searched for clinical outcomes: growth, cardiovascular health, motor development, cognitive development, emotional and behavioral development, language development, and parent-infant interaction. Second, we searched for laboratory and imaging outcomes, including epigenetic alterations (such as DNA methylation and telomere length), alterations of the microbiome, immunologic changes, alterations in the functioning of the HPA axis as expressed in cortisol levels, and changes in structural brain development. These outcomes had to be reported on discharge from the NICU or thereafter to encompass the effects of the entire NICU stay. We excluded studies that regarded animal research and studies written in languages other than English and Dutch. The full search strategy is presented in Table 1 .

Mesh, Medical Subject Headings.

To assess the quality of the studies, we used the Newcastle-Ottawa Quality Assessment Scale for case-control and cohort studies. 20   This scale covers 3 domains: selection, comparability, and exposure in case of case-control studies or outcome in cohort studies. Selection focused on representativeness of the cases and the selection of controls in case-control studies or representativeness of the cohort and the selection of a nonexposed group in cohort studies. Comparability focused on the factors controlled by the study in the statistical analyses. Exposure, in the case of case-control studies, focused on ascertaining exposure and nonresponse rates in follow-up assessments, whereas outcome, in cohort studies, focused on the length and adequacy of follow-up. The total quality assessment score consists of the sum of these 3 domains and ranges from 0 to 9, in which 9 indicates the highest quality. 20  

As far as analysis and reporting is concerned, we first present the flow of studies and the characteristics of the included studies and their quality. Second, we provide a detailed summary of the studies we included regarding associations between neonatal stress and clinical, laboratory, and imaging outcome measures of health and development.

Our search resulted in 20 485 articles. Figure 1 is a flowchart of the study selection procedures. After removing duplicates, we screened 13 670 articles on the basis of their titles and abstracts and found 66 relevant studies. Of these, we excluded 45 because they were conference abstracts, doctoral theses, comments, or books ( n = 22); because they did not meet our inclusion criteria regarding the moment at which neonatal stress occurred ( n = 1); because they did not meet our inclusion criteria regarding the moment at which the outcome had been measured ( n = 12); or because they did not involve original research or fell outside the scope of our search ( n = 10). The latter, for example, dealt with an immediate response to a painful stimulus, with parenting or parental psychosocial stress, or with the predictive value of epigenetic alterations for outcomes later in life, without presenting a measure of neonatal stress. We selected an additional 5 articles from the reference lists, 2 of which fulfilled the inclusion criteria.

Flow of studies. a Two studies included an association with a clinical outcome and a laboratory or imaging outcome, bringing the total number of studies included in qualitative analysis to n = 20. CINAHL, Cumulative Index to Nursing and Allied Health Literature; N/A, not applicable.

Finally, our review consisted of 20 studies. Most studies involved very preterm infants with gestational ages of <32 weeks, as well as control groups of term infants, and examined pain-related stress. In general, the measure used to assess neonatal stress during the NICU stay was skin-breaking procedures. Eleven studies were part of a large cohort study by Grunau and colleagues. 21 – 31   A mere 7 studies extended the scope of neonatal stress beyond pain-related stressors by including exposure to all stressors during the NICU stay: the quality of developmental care, medical stressors (such as all potentially stressful events during the NICU stay associated with medical care based on the Neonatal Infant Stressor Scale 3   ), and maternal separation. 32 – 38   We did not identify studies fulfilling our inclusion criteria that investigated noise or light exposure as stressors. Two studies addressed both clinical and laboratory or imaging outcomes. One study assessed cortisol levels and cognitive and motor development, 35   and the other addressed epigenetic alterations and emotional and behavioral development. 22  

By and large, the quality of the studies was moderate. In most studies, a preterm cohort was combined with a nonexposed group, mainly term children, who had been selected from either the same or a different hospital. 21 – 29 , 33 – 35 , 37 , 39 , 40   A few studies did not include a nonexposed group. 30 – 32 , 36 , 38   In 5 studies, the statistical analyses had not been adjusted for confounding factors, and only unadjusted associations between the stressor and outcome were reported. 24 , 27 , 33 , 34 , 36   Most studies failed to report nonresponse and the characteristics of the participants lost to follow-up. 21 – 29 , 31 , 35 , 40   The authors of 3 studies, in particular, reported on blind assessment of the outcome measures. 25 , 30 , 38   In Supplemental Table 4 , we present detailed quality scores of all the studies, and the total scores are summarized in Tables 2 and 3 .

Findings on Associations Between Neonatal Stress and Clinical Outcomes in Preterm Infants

ECBQ, Early Childhood Behavior Questionnaire; ICC, infant-centered care; IPM, infant pain management; SES, socioeconomic status; → associated with; ↑ increased; ↓ decreased.

Findings on Associations Between Neonatal Stress and Laboratory and Imaging Outcomes in Preterm Infants

BRIEF, Behavioral Inventory of Executive Functioning; CpG, 5′—C—phosphate—G—3′ site; SNAP-II, Score for Acute Neonatal Physiology version II; WISC, Weschler Scale of Intelligence; → associated with; ↑ increased; ↓ decreased.

Medical risk assessed by using a therapeutic intensity or neonatal illness severity score.

Our search yielded studies on cognitive, motor, behavioral, and emotional development, which we summarize in Table 2 . We found no studies on language development, parent-infant bonding, or interaction. Nor did we find studies on the associations between neonatal stress and growth indicators, such as weight, height, BMI, or energy expenditure. Cardiovascular outcomes, such as blood pressure, were not reported either.

Cognitive and Motor Development

In 2 studies, cognitive and motor development were assessed as outcome measures in early infancy and toddlerhood by using the Bayley Scales of Infant and Toddler Development, Second Edition (BSID-II). 24 , 35   One study assessed maternal separation as a neonatal stressor and found no differences between the separated and nonseparated groups on the BSID-II mental and motor subscales. 35   The other study found an association between higher numbers of skin-breaking procedures and lower scores on the mental and motor subscales of the BSID-II at 8 and 18 months. 24  

Emotional and Behavioral Development

Five studies assessed emotional and behavioral outcomes, and all 5 used the Child Behavior Checklist (CBCL) as an outcome measure. 22 , 29 , 34 , 37 , 38   In addition, one study used the Symptom Checklist, 37   and another used the Early Childhood Behavior Questionnaire, which is focused on attention problems in toddlers. 38   In 3 studies, emotional and behavioral problems were assessed during early childhood, 18 to 36 months, 34 , 37 , 38   and at school age, 7 to 11 years. 22 , 29 , 37   Studies consistently reported more emotional and behavioral problems with neonatal stress assessed as either skin-breaking procedures, 22 , 29 , 38   the quality of infant-centered care regarding pain management (assessed by using a 29-item quality of care questionnaire operationalized in these indices), 34   or medical stress (assessed by using the perinatal risk inventory, an 18-item scale on severity of perinatal complications). 37  

Table 3 provides a summary of the laboratory outcomes we found in studies on the functioning of the HPA axis, as expressed in cortisol levels, and epigenetic alterations, both in DNA methylation and telomere length. Our search also yielded studies on structural brain development, which are included in Table 3 . None of the studies we found reported on associations between neonatal stress and changes to the neonatal microbiome or immune system.

HPA Axis Functioning: Cortisol Levels

We identified 5 studies that examined the association between neonatal stress and cortisol levels as an indicator of the functioning of the HPA axis. Measurements were performed in early childhood, 6 to 18 months, 26 , 35   and at school age, 4 to 7 years. 21 , 25 , 31   Cortisol levels were measured in saliva in 4 studies 21 , 26 , 31 , 35   and in hair in another. 25   Findings were contradictory as far as the association between neonatal stress and cortisol levels was concerned. Studies on skin-breaking procedures 21 , 25 , 26 , 31   either found lower levels in diurnal cortisol patterns and during cognitive assessments, 21 , 25   higher levels (particularly in the case of children who were born at extremely low gestational ages), 26   or no relation at all. 31   One study on maternal separation reported no differences in cortisol levels. 35  

Epigenetic Alterations

We found 5 studies that assessed associations between neonatal stress and epigenetic alterations, such as changes in DNA methylation 22 , 33 , 36 , 40   and in telomere length. 39   Four of these studies assessed epigenetic changes between birth and discharge, thus incorporating the full extent of neonatal stress during the NICU stay, 33 , 36 , 39 , 40   whereas one study assessed DNA methylation at the age of 7 years. 22   Three studies assessed DNA methylation of the serotonin transporter gene, SLC6A4 , with consistent results of hypermethylation across different sites. 22 , 33 , 40   In one study, DNA methylation of the glucocorticoid receptor gene, NR3C1, was assessed, and the authors reported that infants with more neonatal stress showed hypomethylation at one specific site. 36   For NR3C1 , the reported hypomethylation is most likely associated with a decrease in gene transcription of the glucocorticoid receptor, whereas for SLC6A4 , hypermethylation is most likely associated with an increased transcription of the serotonin transporter gene. Strikingly, none of the studies reported differences at birth between preterm and term infants in DNA methylation of these 2 genes. Finally, one study reported that in very preterm infants, more neonatal stress was associated with shorter telomere lengths across the epigenome on discharge from the NICU. 39  

Structural Brain Development

Five studies assessed structural brain development as an imaging outcome. Two of these studies used magnetoencephalography, 23 , 27   whereas the other 3 used MRI. 28 , 30 , 32   In the studies using magnetoencephalography, the authors reported that more neonatal stress, assessed as skin-breaking procedures, was associated with increased connectivity, especially in the frontal lobe of the brain. 27   This atypical magnetoencephalography pattern of increased connectivity was in turn associated with decreased visual-perceptual abilities, especially in children born before 28 weeks’ gestation. 23   The studies using MRI reported that more neonatal stress, assessed as the total number of medical stressors during the NICU stay and measured by using either the Neonatal Infant Stressor Scale 32   or skin-breaking procedures, 28 , 30   was associated with increased cortical thickness across the entire brain, more cerebellar hemorrhages, reduced brain volumes in several areas of the brain (including the amygdala and thalamus), or diffuse injury throughout the brain. 28 , 30 , 32  

Our systematic review demonstrates that neonatal stress is associated with a variety of clinical, laboratory, and imaging outcomes directly after an infant’s stay in a NICU and beyond. A higher level of neonatal stress is associated with poorer cognitive, motor, emotional, and behavioral development. In addition, a higher level of neonatal stress is associated with changes in structural brain development in several areas of the brain. We also identified associations between neonatal stress and the functioning of the HPA axis and epigenetic alterations. Our review provides no evidence for other health and developmental outcomes, such as growth, cardiovascular health, language development, parent-infant interaction, and alterations in the neonatal immune system and neonatal microbiome.

We found that neonatal stress is associated with clinical outcomes, that is, cognitive, motor, emotional, and behavioral development. For cognitive and motor development, we identified only 2 studies in early life, 24 , 35   whereas for emotional and behavioral development, several studies over the course of childhood were identified. 22 , 29 , 34 , 37 , 38   Internalizing behavioral and attentional problems in particular seem to increase after higher stress exposure during the NICU stay. 29 , 34 , 37   For preterm infants, neonatal stress during the NICU stay thus seems to be an additional factor that increases the risk of poorer outcomes in these domains. We think that laboratory and imaging outcome measures provide clues regarding the lines along which associations between neonatal stress and these clinical outcomes may be explained.

One intermediate outcome supporting the association between neonatal stress and clinical presentations of neurodevelopmental issues regards structural brain development. In our review, we found stress to be associated with a variety of changes in the structure of the brain. 23 , 27 , 28 , 30 , 32   For example, neonatal stress was associated with alterations in the structure of the frontal lobe, a part of the brain that is essential for social, attentional, and executive development and processing. 27   Moreover, stress was associated with more cerebellar hemorrhages, 32   which may result in coordination disorders, cognitive dysfunction, and behavioral problems because the cerebellum is involved in those functions. 41   Furthermore, the authors of several studies reported that cortical thickness across diffuse brain regions was affected. 27 , 28 , 32   An increase in cortical thickness may lead to a variety of problems involving intellect and other high-order cognitive functions. 42   Previously, many of the regions affected were reported to be involved in spatial orientation and memory. 30   The findings underline the hypothesis that structural brain development may be affected by stress occurring in the neonatal period, during which the brain is extremely sensitive to environmental stimuli. The mediating role of structural changes to the brain is also confirmed by the fact that, particularly, internalizing and attention problems were found to be associated with neonatal stress. Functions relating to emotion and attention indeed originate in the frontal lobe, cerebellum, and cortical areas throughout the brain, which are reported to be affected by neonatal stress.

In our review, laboratory findings, particularly those related to the functioning of the HPA axis, were other outcomes we identified that supported the associations between neonatal stress and clinical presentations of neurodevelopmental problems. These alterations in function of the HPA axis (ie, cortisol dysregulation) had conflicting directions (ie, either increased 26   or decreased levels 21 , 25   ). Both directions may contribute to a deterioration of the infants’ health. 43   In preterm-born children, altered cortisol levels are associated with attention problems. 21   In studies on other areas of stress during early life, including maltreatment or traumatic events, alterations in HPA axis settings were also reported. 43   This phenomenon is labeled stress sensitization and is hypothesized to be a mechanism responsible for the observed association between exposure to stressors in early life and emotional and behavioral development, specifically anxiety and depression. 43 , 44   Additionally, altered cortisol levels are associated with growth and cardiovascular health. 45   Alterations in the settings of the HPA axis may therefore also be a mechanism in the association between neonatal stress and clinical outcomes.

Moreover, we identified several studies reporting that epigenetic alterations of the two most studied genes, NR3C1 and SLC6A4 , were associated with exposure to neonatal stressors. 22 , 33 , 36 , 40   These alterations are also associated with social-emotional development, 46   poorer neurodevelopmental outcomes, 13   and brain growth. 47   Several studies on other circumstances in which stress occurs during early life also reported associations between epigenetic alterations and problems later on, including stress hypersensitivity, 48   neuroendocrine dysregulation, 39   anxiety, and depression. 49   In addition, cross-links exist with the HPA axis because epigenetic alterations have been associated with altered cortisol reactivity in preterm-born infants. 50   Thus, epigenetic alterations may be the molecular mechanism underlying the functioning of the HPA axis and associated clinical findings. Moreover, these alterations may also be the basis for structural changes in brain development because these receptors are widely expressed in the human brain and are involved in the early processes of neuronal formation. 47  

By using the Newcastle-Ottawa Scale for Quality Assessment 20   the quality of the included studies appeared to be moderate. All included studies were observational, that is, either cohort or case-control studies. This cannot be considered a real limitation nor can it be avoided because, for ethical reasons, observational studies are the only type of study on stress exposure possible in human neonates. Studies further differed regarding their definition of neonatal stress, which hampered comparisons between them. Many studies only investigated skin-breaking procedures as neonatal stress, thus possibly underestimating the accumulation of stressors infants are exposed to during the NICU stay. The kind of neonatal stress may also have influenced the results. In the cognitive and motor outcomes, for example, maternal separation was not associated with lower BSID-II scores, 35   whereas this was the case for skin-breaking procedures. 24   Finally, we were surprised that we did not find any studies investigating sound and light as stressors during the NICU stay in relation to long-term outcomes. A definition of neonatal stress incorporating the full extent of exposure to neonatal stressors therefore warrants urgent attention.

This is the first systematic review of the literature on a wide range of health and developmental outcomes, including clinical, laboratory, and imaging outcome measures associated with all kinds of neonatal stress. The strengths of the review lie in the extensive search algorithm deployed and in the full assessment of the studies by two reviewers. A limitation is that given the limited number of eligible studies, we were unable to provide a meta-analysis. Second, we only included studies in English and Dutch, which may have led to missing some studies.

Our review implies that a wide range of neonatal stressors should be taken into consideration during neonatal care and follow-up of preterm children. Follow-up programs for preterm NICU graduates should address the impact of neonatal stress and should highlight the need for structural recording of neonatal stress during the NICU stay. Physicians and NICU nursing staff alike should watch for any early signs of developmental and health-related effects of neonatal stress that may warrant early intervention aimed at improving day-to-day functioning. 51 – 53   Minimizing the exposure of neonates to stress during the NICU stay is therefore of the utmost importance and is achieved either through improving individualized developmental care or through initiating nonpharmacologic interventions. In animal studies, for example, the effect of the exposure to neonatal pain-related stress is buffered by maternal licking and grooming, 54 , 55   behavior that may also hold true for human neonates. 56  

For the purpose of future research, the definition of neonatal stress should be expanded to include stressors beyond skin-breaking procedures to determine if a composite of stressors represent the total burden of neonatal stress in preterm infants more accurately. Unraveling these various types of neonatal stress and their associations with clinical outcomes is key for improvement of neonatal care. With this review, we show that only few long-term studies exist beyond skin-breaking procedures. Studies are needed on the full extent of exposures during the NICU stay, including noise, light, handling, maternal separation, nursing procedures, and medical procedures. A broader definition of neonatal stress is also key to expanding our knowledge of the effects of neonatal stress on health and development in preterm-born infants and to further elucidating the pathways between neonatal stress and laboratory, imaging, and clinical outcomes, as was conceptualized in a recent study. 57   In such research, several outcome domains and potential mechanisms may be of interest because of their likely associations with neonatal stress. Outcome domains should also include growth and cardiovascular health, 58 , 59   whereas a potential mechanism may be the role of the neonatal immune system. 14  

Our review underscores that neonatal stress is associated with a wide range of outcomes, including clinical (neurologic development as well as emotional and behavioral development), laboratory (altered HPA axis settings and epigenetic alterations), and imaging (structural brain development), after preterm birth. Nevertheless, to date evidence is lacking regarding several other clinical outcomes, such as growth and cardiovascular health, language development, and parent-infant interaction, as well as outcomes related to potential mechanisms, such as functioning of the neuroendocrine and immune systems and the neonatal microbiome. Pediatricians and neonatologists should try to minimize exposure to stressors during the NICU stay as much as possible. Physicians and other caregivers involved in neonatal care and follow-up should be consciously aware of the impact of neonatal stress on preterm children.

We kindly thank D.G. van Ittersum for her help with assembling the search strategy and performing the literature search. We also thank T. van Wulfften Palthe, PhD, for correcting the English manuscript.

Ms van Dokkum conceptualized and designed the study, performed the literature search, drafted the initial manuscript, and revised the manuscript after feedback from coauthors; Dr de Kroon conceptualized and designed the study, performed the literature search, and critically reviewed and revised the manuscript; Drs Reijneveld and Bos conceptualized and designed the study and critically reviewed and revised the manuscript; and all authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.

FUNDING: No external funding.

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Case Study of an Infancy Period

Infancy is a period when the most dramatic developmental changes happen in a human. The following essay will investigate multiple aspects of an infant’s development and the role of caregivers illustrated by the example of a 4-year old girl named Ann.

Ann was born full-term, weighing about 6 lbs with a length of 18 in. After 6 months, she weighed 14 lbs, and her length was 24 in. By the age of 2, the girl gained a significant amount of weight , which was 25 lbs, and her length became 32 in. As a newborn, Ann had erratic and irregular sleeping patterns falling asleep when it was time to eat or staying up all night crying. The situation changed when she was around 6-months old, and her sleeping patterns became more predictable. Ann needed 9 hours as she approached her first year of life. Toilet training began as the girl stopped using nappies at 18-months. She did not feel comfortable using a potty initially, but by the age of 3, she was completely ready to use it regularly.

Ann was able to stand and sit with support at 3 months. During her first year of life, she reached another milestone and learned to walk without support maintaining balance. As her motor development progressed by the age of 2, she could walk confidently and squat to pick up toys from the floor. Ann’s favorite visual stimuli was a brightly-colored bear-shaped pillow. She also loved lullabies and nursery rhymes , such as Twinkle Twinkle Little Star and One Little Finger. As Ann got older, she started to enjoy listening to bedtime stories about princesses like Cinderella or Snow White. Her favorite toy at the time when her teeth started to show up was a bunny-shaped teether, which would bring her comfort and relief the pain. It was later replaced by a soft teddy bear that she enjoyed to touch . Ann did not sustain any serious injuries as a baby and a toddler, but she would sometimes get bumps and scratches after playing outside. As a baby, she would cry a lot from pain , but later became more confident and cried less in case of a minor injury.

Before the age of 2, Ann disliked most meals that she was offered. Later on, she began to enjoy the taste of her favorite foods , such as eggs or cheese, and the smell of fruit. However, most vegetables were still her least favorite foods . Ann learned mostly through classical ways of observation as well as imitation during play and activities with her mother. Operant conditioning , which involves rewards and punishment, was also present in Ann’s development during her toilet training and feeding. By the age of 6 months, her language development included making different sounds to interact with parents and trying to repeat the words after them. By 12 months, the girl was able to say a few words and respond to simple phrases. By the age of 18 months, she could point at familiar things, while a 2-year old Ann became confident with action words and used them during playtime.

Ann was an emotional child before the age of 2, who cried a lot when she could not get whatever she wanted. After her 2nd birthday, she became more patient. Her crying patters changed too, and she cried considerably less. Ann used to get scared in situations that involved meeting strangers walking away from unfamiliar people and feeling anxious when they touched her. She did not show any signs of stranger anxiety at the age of 2. In general, infants have different emotional styles that reflect their temperament i.e., “individual differences in behavioral styles, emotions, and characteristic ways of responding” (Santrock, 2018, p. 117). According to the classification based on temperament, there are 3 types of children: easy, difficult, and slow-to-warm-up. An easy child is usually in a good mood and adjusts easily to new events. A difficult child has a negative attitude, cries often, and has difficulty adapting to change. Slow-to-warm-up child might be negative and has a low intensity of mood. Based on the definitions, Ann might be classified as a difficult child since she used to cry a lot and expressed a negative attitude to her environment.

Santrock (2018) defined attachment as “a close emotional bond between two people” (p. 124). The Strange Situation is used to measure infants’ attachment during a series of “introductions, separations, and reunions with caregiver” (p. 125). Babies can be described as securely attached, insecure avoidant, insecure resistant, and insecure disorganized based on their response to the Strange Situation. Securely attached babies feel safe when their caregiver is present, while insecure avoidant babies express their negative feelings by avoiding the caregiver. Insecure resistant babies get close to the caregiver at first but then push her/ him away. Finally, insecure disorganized babies are disoriented, fearful, and confused in the Strange Situation. Ann was a securely attached baby, as she would cling to her mother when faced with unfamiliar situations refusing to let her mother go. Because of Ann’s strong attachment, her mother decided to take care of the baby by herself instead of putting her in daycare . As a result, the girl became more attached to her parents and had difficulties interacting with strangers and other children.

Overall, the real-life example of Ann helped to illustrate the gradual changes in behavior, attitude, and cognitive development of a child as these characteristics are becoming more complex as time goes by. The analysis of the infant’s developmental peculiarities at different stages of life demonstrated how dramatic these changes are and how they can be affected by caregivers.

Santrock, J. W. (2018). Essentials of life-span development (5th ed.). New York, NY: McGraw-Hill Education.

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The lasting impact of neglect

Psychologists are studying how early deprivation harms children — and how best to help those who have suffered from neglect.

By Kirsten Weir

June 2014, Vol 45, No. 6

Print version: page 36

10 min read

• Mental Health

The babies laid in cribs all day, except when being fed, diapered or bathed on a set schedule. They weren't rocked or sung to. Many stared at their own hands, trying to derive whatever stimulation they could from the world around them. "Basically these kids were left on their own," Fox says.

Fox, along with colleagues Charles Nelson, PhD, at Harvard Medical School and Children's Hospital Boston, and Charles Zeanah, MD, at Tulane University, have followed those children for 14 years. They describe their Bucharest Early Intervention Project in a new book, "Romania's Abandoned Children: Deprivation, Brain Development, and the Struggle for Recovery" (2014).

Neglect isn't just a Romanian problem, of course. UNICEF estimates that as many as 8 million children are growing up in institutional settings around the world. In the United States, neglect is a less obvious — though very real — concern. According to a report by the U.S. Department of Health and Human Services, 676,569 U.S. children were reported to have experienced maltreatment in 2011. Of those, more than 78 percent suffered from neglect.

The list of problems that stem from neglect reads like the index of the DSM: poor impulse control, social withdrawal, problems with coping and regulating emotions, low self-esteem, pathological behaviors such as tics, tantrums, stealing and self-punishment, poor intellectual functioning and low academic achievement. Those are just some of the problems that David A. Wolfe, PhD, a psychologist at the University of Toronto, and his former student Kathryn L. Hildyard, PhD, detailed in a 2002 review ( Child Abuse & Neglect , 2002).

"Across the board, these are kids who have severe problems throughout their lifetime," says Wolfe, recent past editor-in-chief of Child Abuse & Neglect .

Now, researchers are beginning to understand some of the ways that early deprivation alters a person's brain and behavior — and whether that damage can be undone.

The Bucharest project

In 1989 Romanian dictator Nicolae Ceauşescu was overthrown, and the world discovered that 170,000 children were being raised in Romania's impoverished institutions. As the children's plight became public, Fox, Nelson and Zeanah realized they had a unique opportunity to study the effects of early institutionalization.

The trio launched their project in 2000 and began by assessing 136 children who had been living in Bucharest's institutions from birth. Then they randomly assigned half of the children to move into Romanian foster families, whom the researchers recruited and assisted financially. The other half remained in care as usual. The children ranged in age from 6 months to nearly 3 years, with an average age of 22 months.

Over the subsequent months and years, the researchers returned to assess the development of the children in both settings. They also evaluated a control group of local children who had never lived in an institution.

They found many profound problems among the children who had been born into neglect. Institutionalized children had delays in cognitive function, motor development and language. They showed deficits in socio-emotional behaviors and experienced more psychiatric disorders. They also showed changes in the patterns of electrical activity in their brains, as measured by EEG.

For kids who were moved into foster care, the picture was brighter. These children showed improvements in language, IQ and social-emotional functioning. They were able to form secure attachment relationships with their caregivers and made dramatic gains in their ability to express emotions.

While foster care produced notable improvements, though, children in foster homes still lagged behind the control group of children who had never been institutionalized. And some foster children fared much better than others. Those removed from the institutions before age 2 made the biggest gains. "There's a bit of plasticity in the system," Fox says. But to reverse the effects of neglect, he adds, "the earlier, the better."

In fact, when kids were moved into foster care before their second birthdays, by age 8 their brains' electrical activity looked no different from that of community controls. The researchers also used structural MRI to further understand the brain differences among the children. They found that institutionalized children had smaller brains, with a lower volume of both gray matter (which is made primarily of the cell bodies of neurons) and white matter (which is mainly the nerve fibers that transmit signals between neurons).

"A history of institutionalization significantly affected brain growth," Fox says.

The institutionalized children who were moved into foster homes recovered some of that missing white matter volume over time. Their gray matter volume, however, stayed low, whether or not they had been moved into stable homes ( PNAS , 2012). Those brain changes, the researchers found, were associated with an increased risk of ADHD symptoms.

Many of the children remain with their foster families. (The researchers no longer support those families financially, but the Romanian government continues to provide stipends for the children's care.) Soon, Fox says, he and his colleagues will begin the 16-year assessment. They expect that to be particularly telling, since the effects of adversity in early childhood can re-emerge during adolescence.

Regardless of future findings, Fox has seen enough evidence to draw hard conclusions. "Children need to be in socially responsive situations. I personally think that there aren't good institutions for young children," he says. With millions of children growing up in similar conditions, he adds, "this is a worldwide public health issue."

Coming to America

In the United States, Megan Gunnar, PhD, director of the Institute of Child Development at the University of Minnesota, has helped fill in other pieces of the puzzle. In 1999, she and her colleagues launched the International Adoption Project, an extensive examination of children adopted from overseas. She now has nearly 6,000 names on her registry and her research is ongoing.

Gunnar has found certain brain changes are common among children who came to the United States from orphanages, including a reduction in brain volume and changes in the development of the prefrontal cortex.

"Neglect does a number on the brain. And we see behaviors that follow from that," she says.

She's found post-institutionalized kids tend to have difficulty with executive functions such as cognitive flexibility, inhibitory control and working memory. They are often delayed in the development of theory of mind, the ability to understand the mental states of others. Many struggle to regulate their emotions. Often, they suffer from high anxiety.

One of the most common behaviors she sees among post-institutionalized children is indiscriminate friendliness. "A child who doesn't know you from Adam will run up, put his arms around you and snuggle in like you're his long-lost aunt," Gunnar says. That friendliness was probably an important coping technique in their socially starved early lives, she says. "What's interesting is it just doesn't go away."

Fox and his colleagues had also noted such disarming friendliness in the Romanian orphanages. Initially, children with indiscriminate friendliness were thought to have an attachment disorder that prevented them from forming healthy connections with adult caregivers. But findings from the Bucharest Project as well as Gunnar's own research have demonstrated otherwise, she says.

In a study of 65 toddlers who had been adopted from institutions, Gunnar found that most attached to their new parents relatively quickly, and by nine months post-adoption, 90 percent of the children had formed strong attachments to their adoptive parents. Yet that attachment was often "disorganized," marked by contradictory behaviors ( Development and Psychopathology , in press). A child might appear confused in the presence of a caregiver, for instance, sometimes approaching the caregiver for comfort, and other times showing resistance.

"There were things that happened in terms of early development, when they lacked that responsive caregiver, that they're carrying forward," Gunnar says.

One of those things may be a disrupted cortisol pattern. Cortisol, commonly known as the "stress hormone," typically peaks shortly after waking, then drops throughout the day to a low point at bedtime. But Gunnar found that children with a history of neglect typically have a less marked cortisol rhythm over the course of the day. Those abnormal cortisol patterns were correlated with both stunted physical growth and with indiscriminate friendliness ( Development and Psychopathology , 2011).

Indiscriminate friendliness may also be tied to the amygdala. In a study using fMRI, Aviva Olsavsky, MD, at the University of California, Los Angeles, and colleagues found that when typical children viewed photos of their mothers versus photos of strangers, the amygdala showed distinctly different responses. In children who had been institutionalized, however, the amygdala responded similarly whether the children viewed mothers or strangers. That response was particularly notable among kids who exhibited more friendliness toward strangers ( Biological Psychiatry , 2013).

Closer to home

Other researchers are also exploring physiological differences in children who have experienced neglect. Around the time Gunnar was launching her adoption study, Philip Fisher, PhD, a psychologist and research scientist at the University of Oregon, was working with American foster children. Initially, he suspected the behavioral and developmental difficulties they experienced stemmed from physical abuse. But as he shared data with Gunnar and others, he realized they looked a lot like post-institutionalized children.

Though cortisol tends to follow a daily cycle, it also spikes during times of stress. Fisher expected that his foster children, who had clearly experienced stressful situations, might show high levels, too. Instead, he discovered something quite different. "Their levels were low in the morning and stayed low throughout the day," he says.

Combing through the case records of the children in his sample, he discovered that disregulated cortisol was not associated with physical or sexual abuse, but with early neglect. "This blunted daily pattern with low morning cortisol seemed to be a hallmark of neglect," he says. "That was a pretty powerful picture."

In fact, abnormal cortisol cycles have previously been noted in a variety of psychological disorders, Fisher says, including anxiety, mood disorders, behavior problems and post-traumatic stress disorder. But the good news: Cortisol patterns appear to be changeable.

Fisher found that foster kids living with more responsive caregivers were more likely to develop more normal cortisol patterns over time. Kids living with caregivers who were stressed out themselves didn't show that recovery ( Psychoneuroendocrinology , 2007). "We're more likely to see that blunted pattern when they don't get that support, and there's a lot of stress in the family," he says.

Helping caregivers manage their own stress and develop more positive interactions with their children may help reset the kids' stress responses. Fisher is now developing and testing video coaching programs that aim to identify and reinforce the positive interactions foster parents are already having with their young children. "We can show people very precisely the things we know are at the core of promoting healthy development," he says.

Meanwhile, he's also looking for other physiological systems affected by early adverse experience — particularly those that are malleable. "If we can impact those systems, especially without pharmacology, we have great tools we can leverage," he says.

For instance, kids with a history of neglect are known to have trouble with executive functioning. One way that presents itself is that the kids don't show much brain response to corrective feedback; instead, they often make the same mistakes over and over. Targeted interventions may help those children learn to tune in to the important cues they're missing, Fisher says. Though more research is needed, he adds, computer-based brain-training games and other novel interventions might prove to be useful complements to more traditional therapy.

Despite progress, child neglect remains underfunded and understudied, says Wolfe. Politically, it's a prickly subject. "Neglect is not a disease. It's entwined with the delivery of proper social and medical services. It's embedded in socioeconomic disadvantage," he says.

Politics aside, science is making strides toward erasing the stamp that early neglect leaves on a child. New understanding of the ways that neglect changes a person's physiology is helping to push the field forward, Wolfe says.

That progress is sorely needed, but the most important first step is to remove neglected children to a safe, loving environment, he adds. "The brain will often recover, if it's allowed to."

Kirsten Weir is a journalist in Minneapolis.

Further reading

• Bruce, J., Gunnar, M. R., Pears, K. C., and Fisher, P. A. (2013). Early adverse care, stress neurobiology, and prevention science: Lessons learned. Prevention Science, 14 (3), 247–256.
• Nelson, C. A., Fox, N. A., and Zeanah, C. H. (2014). Romania's abandoned children: Deprivation, brain development, and the struggle for recovery . Cambridge, MA, and London, England: Harvard University Press.
• Nelson III, C. A., Zeanah, C. H., Fox, N. A., Marshall, P. J., Smyke, A. T., and Guthrie, D. (2007). Cognitive recovery in socially deprived young children: the Bucharest Early Intervention Project. Science, 318 (5858), 1937–2940.

Digital Edition

• Video: Izidor Ruckel is a Romanian orphan who has made it his life’s work to help other orphans .

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1 Introduction to Infant and Child Development

Learning objectives.

After reading Chapter 1, you should be better equipped to:

• Describe the principles that underlie development.
• Differentiate  periods of human development
• Understand the theoretical questions posed by developmental psychologists.
• Explain the concept of a theory.
• Compare and contrast different theories of child development.

  Why Study Infants and Children from a Psychological Perspective?

From the perspective of a parent, seeing your child develop can be both rewarding and challenging.  Hearing your child say his or her first word, or watching your child take their first steps are memories a parent will never forget. However, why should the development of infants and children be of interest from a psychological perspective?  What information can be gained from such study, and how can this information be used to benefit others? [1]

Two of the key goals involved in the study of infant and child development focus on:

• Describing change – many of the studies we will examine simply involve the first step in investigation, which is description. Arnold Gesell’s study on infant motor skills, for example.
• Explaining change – Theories provide explanations for why we change over time. For example, Erikson offers an explanation about why a two-year-old might be temperamental.

Think about how you were 5, 10, or even 15 years ago.  In what ways have you changed?  In what ways have you remained the same?  You have probably changed physically; perhaps you have grown taller and become heavier.  But you may have also experienced changes in the way you think and solve problems. [2]

Development is multidimensional and as we grow, we change across three general domains or dimensions, the physical, the cognitive, and the social/emotional.

The physical domain includes changes in height and weight, changes in gross and fine motor skills, sensory capabilities, the nervous system, as well as the propensity for disease and illness.  The cognitive domain encompasses the changes in intelligence, wisdom, perception, problem-solving, memory, and language.  The social and emotional domain (also referred to as psychosocial) focuses on changes in emotion, self-perception, and interpersonal relationships with families, peers, and friends. [3]

Emotional, social, and cognitive change is noticeable when we compare how 1-year-olds, 3-year-olds, and 6-year-olds think and reason.  Their thoughts about others and the world are quite different.  Consider play for instance.  The typical 1-year-old will play alone with little interaction, whereas the 3-year-old will play alongside others, but not play together, and the 6-year-old plays cooperatively with others often with a shared goal. [4]

It is important to understand that all three domains influence each other, and that change in one domain may cascade and prompt changes in the other domains.  In addition, development in each domain is characterized by plasticity, which is our ability to change and many of our characteristics are malleable. Early experiences are important, but children are remarkably resilient and able to overcome adversity.

Finally, Development is multi-contextual .  We are influenced by both nature (genetics) and nurture (the environment) – when and where we live and our actions, beliefs, and values are a response to circumstances surrounding us, and it is important to understand that physical growth, behavior, motivation, emotion, and choice are all part of a bigger picture. [5]

Periods of Development

Think about what periods of development that you think a course on Child Development would address. How many stages are on your list? Perhaps you have three: infancy, childhood, and teenagers. Developmentalists (those that study development) break this part of the life span into these five stages as follows:

Prenatal Development (conception through birth)

Infancy and Toddlerhood (birth through two years)

Early Childhood (3 to 5 years)

Middle Childhood (6 to 11 years)

Adolescence (12 years to adulthood)

This list reflects unique aspects of the various stages of childhood and adolescence that will be explored in this book. So while both an 8 month old and an 8 year old are considered children, they have very different motor abilities, social relationships, and cognitive skills. Their nutritional needs are different and their primary psychological concerns are also distinctive.

Prenatal Development

Conception occurs and development begins. All of the major structures of the body are forming and the health of the mother is of primary concern. Understanding nutrition, teratogens (or environmental factors that can lead to birth defects), and labor and delivery are primary concerns.

Infancy and Toddlerhood

The first two years of life are ones of dramatic growth and change. A newborn, with a keen sense of hearing but very poor vision is transformed into a walking, talking toddler within a relatively short period of time. Caregivers are also transformed from someone who manages feeding and sleep schedules to a constantly moving guide and safety inspector for a mobile, energetic child.

Early Childhood

Early childhood is also referred to as the preschool years and consists of the years which follow toddlerhood and precede formal schooling. As a three to five-year-old, the child is busy learning language, is gaining a sense of self and greater  workings of the physical world. This knowledge does not come quickly, however, and preschoolers may initially have interesting conceptions of size, time, space and distance such as fearing that they may go down the drain if they sit at the front of the bathtub or by demonstrating how long something will take by holding out their two index fingers several inches apart. A toddler’s fierce determination to do something may give way to a four-year old’s sense of guilt for action that brings the disapproval of others.

Middle Childhood

The ages of six through eleven comprise middle childhood and much of what children experience at this age is connected to their involvement in the early grades of school. Now the world becomes one of learning and testing new academic skills and by assessing one’s abilities and accomplishments by making comparisons between self and others. Schools compare students and make these comparisons public through team sports, test scores, and other forms of recognition. Growth rates slow down and children are able to refine their motor skills at this point in life. And children begin to learn about social relationships beyond the family through interaction with friends and fellow students.

Adolescence

Adolescence is a period of dramatic physical change marked by an overall physical growth spurt and sexual maturation, known as puberty. It is also a time of cognitive change as the adolescent begins to think of new possibilities and to consider abstract concepts such as love, fear, and freedom. Ironically, adolescents have a sense of invincibility that puts them at greater risk of dying from accidents or contracting sexually transmitted infections that can have lifelong consequences. [6]

Theoretical Questions in Development

Nature and nurture.

Why are you the way you are? As you consider some of your features (height, weight, personality, being diabetic, etc.), ask yourself whether these features are a result of heredity or environmental factors, or both. Chances are, you can see the ways in which both heredity and environmental factors (such as lifestyle, diet, and so on) have contributed to these features. For decades, scholars have carried on the "nature/nurture" debate . For any one feature, those on the side of nature would argue that heredity plays the most important role in bringing about that feature. Those on the side of nurture would argue that one’s environment is most significant in shaping the way we are. This debate continues in all aspects of human development, and most scholars agree that there is a constant interplay between the two forces. It is difficult to isolate the root of any single behavior as a result solely of nature or nurture.

Continuity versus Discontinuity

Is human development best characterized as a slow, gradual process, or is it best viewed as one of more abrupt change? The answer to that question often depends on which developmental theorist you ask and what topic is being studied. The theories of Freud, Erikson, Piaget, and Kohlberg are called stage theories. Stage theories or discontinuous development assume that developmental change often occurs in distinct stages that are qualitatively different from each other, and in a set, universal sequence. At each stage of development, children and adults have different qualities and characteristics. Thus, stage theorists assume development is more discontinuous. Others, such as the behaviorists, Vygotsky, and information processing theorists, assume development is a more slow and gradual process known as continuous development . For instance, they would see the adult as not possessing new skills, but more advanced skills that were already present in some form in the child. Brain development and environmental experiences contribute to the acquisition of more developed skills.

Continuous versus Discontinuous Development

A graphic image describing continuous and discontinuous stage development.  The tree represents continuous development, while the ladybug represents discontinuous  development . [7]

Active versus Passive

How much do you play a role in your own developmental path? Are you at the whim of your genetic inheritance or the environment that surrounds you? Some theorists see humans as playing a much more active role in their own development. Piaget, for instance believed that children actively explore their world and construct new ways of thinking to explain the things they experience. In contrast, many behaviorists view humans as being more passive in the developmental process.

Stability versus Change

How similar are you to how you were as a child? Were you always as out-going or reserved as you are now? Some theorists argue that the personality traits of adults are rooted in the behavioral and emotional tendencies of the infant and young child. Others disagree and believe that these initial tendencies are modified by social and cultural forces over time.

Investment in Early Childhood Development Lays the Foundation for a Prosperous and Sustainable Society [8]

The first years of life are important, because what happens in early childhood can matter for a lifetime. Science shows us what children must have, and what they need to be protected from, in order to promote their healthy development. Stable, responsive, nurturing relationships and rich learning experiences in the earliest years provide lifelong benefits for learning, behavior and both physical and mental health.  In contrast, research on the biology of stress in early childhood shows how chronic stress caused by major adversity, such as extreme poverty, abuse or neglect, can weaken developing brain architecture and permanently set the body’s stress response system on high alert, thereby increasing the risk for a range of chronic diseases.

The following basic concepts established over decades of neuroscience and behavioral research, help illustrate why healthy child development from birth to five years provides a foundation for a prosperous and sustainable society.

Brains are built over time, from the bottom up. The basic architecture of the brain is constructed through an ongoing process that begins before birth and continues into adulthood. Early experiences affect the quality of that architecture by establishing either a sturdy or a fragile foundation for the learning, health and behavior that follow.  In the first few years of life, 700 new neural connections (called synapses) are formed every second.  After this period of rapid proliferation, these connections are reduced through a process called pruning, so that brain circuits become more efficient.  Sensory pathways, like those for basic vision and hearing, are the first to develop, followed by early language skills and later by higher cognitive functions. Connections proliferate and prune in a prescribed order, with later, more complex brain circuits built upon earlier, simpler circuits.

The interactive influences of genes and experience shape the developing brain. Scientists now know a major ingredient in this developmental process is what has been called a “serve and return” relationship between children and their parents and other caregivers in the family or community. Young children naturally reach out for interaction through babbling, facial expressions and gestures, and adults respond with similar kinds of vocalizing and gesturing back at them.  In the absence of such responses – or if the responses are unreliable or inappropriate – the brain’s architecture does not form as expected, which can lead to disparities in learning and behavior.

The brain’s capacity for change decreases with age. It is most flexible, or “plastic,” early in life to accommodate a wide range of environments and interactions, but as the maturing brain becomes more specialized to assume more complex functions, it is less capable of reorganizing and adapting to new or unexpected challenges. For example, by the end of the first year, the parts of the brain that differentiate sounds are becoming specialized according to the language the baby has heard. At the same time, the brain is already starting to lose the ability to recognize different sounds found in other languages. Although the “windows” for complex language learning and other skills remain open, these brain circuits become increasingly difficult to alter over time. Early plasticity means it’s easier and more effective to influence a baby’s developing brain architecture than to rewire parts of its circuitry during adolescence and the adult years.

Cognitive, emotional, and social capacities are inextricably intertwined throughout the life course. The brain is a highly integrated organ, and its multiple functions operate in a richly coordinated fashion. Emotional well-being and social competence provide a strong foundation for emerging cognitive abilities, and together they are the bricks and mortar that make up the foundation of human development. The emotional and physical health, social skills and cognitive-linguistic capacities that emerge in the early years are all important prerequisites for success in school and, later, in the workplace and community.

Although learning how to cope with adversity is an important part of healthy child development, excessive or prolonged stress can be toxic to the developing brain. When we are threatened, our bodies activate a variety of physiological responses, including increases in heart rate, blood pressure, and stress hormones, such as cortisol. When a young child is protected by supportive relationships with adults, he learns how to adapt to everyday challenges and his stress response system returns to baseline. Scientists call this positive stress. Tolerable stress occurs when more serious difficulties, such as the loss of a loved one, a natural disaster, or a frightening injury, are buffered by caring adults who help the child adapt, thereby mitigating the potentially damaging effects of abnormal levels of stress hormones. When strong, frequent or prolonged adverse experiences, such as extreme poverty or repeated abuse, are experienced without adult support, stress becomes toxic and disrupts developing brain circuits. Toxic stress experienced early in life can also have a cumulative toll on learning capacity as well as physical and mental health. The more adverse experiences in childhood, the greater the likelihood of developmental difficulties and other problems. Adults with more adverse experiences in early childhood are also more likely to have chronic health problems, including alcoholism, depression, heart disease and diabetes.

Early intervention can prevent the consequences of early adversity. Research shows that later interventions are likely to be less successful – and in some cases are ineffective. For example, when children who experienced extreme neglect were placed in responsive foster care families before age two, their IQs increased more substantially and their brain activity and attachment relationships were more likely to become normal than if they were placed after the age of two. While there is no “magic age” for intervention, it is clear that, in most cases, intervening as early as possible is significantly more effective than waiting.

Stable, caring relationships are essential for healthy development. Children develop in an environment of relationships that begin in the home and include extended family members, early care and education providers, and other members of the community.  Studies show that toddlers who have secure, trusting relationships with their parents or non-parent caregivers experience minimal stress hormone activation when frightened by a strange event, and those who have insecure relationships experience a significant activation of the stress response system.  Numerous scientific studies support the conclusion that providing supportive, responsive relationships as early in life as possible can prevent or reverse the damaging effects of toxic stress.

The basic principles of neuroscience indicate that providing supportive conditions for early childhood development is more effective and less costly than attempting to address the consequences of early adversity later. To this end, a balanced approach to emotional, social, cognitive and language development will best prepare all children for success in school and later in the workplace and community. For children experiencing toxic stress, specialized interventions – as early as possible – are needed to target the cause of the stress and protect the child from its consequences.

From pregnancy through early childhood, all of the environments in which children live and learn, and the quality of their relationships with adults and caregivers, have a significant impact on their cognitive, emotional and social development. A wide range of policies, including those directed toward early care and education, primary health care, child protective services, adult mental health, and family economic supports, among many others, can promote the safe, supportive environments and stable, caring relationships that children need.

Theories of Development

What is a theory.

Students sometimes feel intimidated by theory ; even the phrase, “Now we are going to look at some theories…” is met with blank stares and other indications that the audience is now lost. But theories are simply an explanation of something and can be valuable tools for understanding human behavior.  In fact, developmental theories offer explanations about how we develop, why we change over time and the kinds of influences that impact development. [9]

Theories help guide and interpret research findings by providing researchers with help putting together various research findings. Think of theories as a story that is used to both explain behaviors and to guide research.  Each time a researcher conducts an experiment to test the validity of a theory another page is being added to the story.  The instructions can help one piece together smaller parts more easily than if trial and error are used.

Historical Theories of Development

John locke(1632-1704) [10].

John Locke, a British philosopher, refuted the idea of innate knowledge and instead proposed that children are largely shaped by their social environments, especially their education as adults teach them important knowledge. He believed that through education a child learns socialization, or what is needed to be an appropriate member of society. Locke advocated thinking of a child’s mind as a tabula rasa or blank slate, and whatever comes into the child’s mind comes from the environment. Locke emphasized that the environment is especially powerful in the child’s early life because he considered the mind the most pliable then. Locke indicated that the environment exerts its effects through associations between thoughts and feelings, behavioral repetition, imitation, and rewards and punishments (Crain, 2005). Locke’s ideas laid the groundwork for the behavioral perspective and subsequent learning theories of Pavlov, Skinner and Bandura.

Jean-Jacques Rousseau (1712-1778) [11]

Like Locke, Rousseau also believed that children were not just little adults. However, he did not believe they were blank slates, but instead developed according to a natural plan which unfolded in different stages (Crain, 2005). He did not believe in teaching them the correct way to think but believed children should be allowed to think by themselves according to their own ways and an inner, biological timetable. This focus on biological maturation resulted in Rousseau being considered the father of developmental psychology. Followers of Rousseau’s developmental perspective include Gesell, Montessori, and Piaget. [12]

Contemporary Theories of Development

Psychoanalytic theories, sigmund freud (1856-1939) and psychoanalytic theory [13].

Freud’s Background

Sigmund Freud (1856-1939) was a Viennese M. D. who was trained in neurology and asked to work with patients suffering from hysteria, a conditioned marked my uncontrollable emotional outbursts, fears and anxiety that had puzzled physicians for centuries. He was also asked to work with women who suffered from physical symptoms and forms of paralysis which had no organic causes. During that time, many people believed that certain individuals were genetically inferior and thus more susceptible to mental illness. Women were thought to be genetically inferior and thus prone to illnesses such as hysteria (which had previously been attributed to a detached womb which was traveling around in the body).

However, after World War I, many soldiers came home with problems similar to hysteria. This called into questions the idea of genetic inferiority as a cause of mental illness.  Freud began working with hysterical patients and discovered that when they began to talk about some of their life experiences, particularly those that took place in early childhood, their symptoms disappeared. This led him to suggest the first purely psychological explanation for physical problems and mental illness. What he proposed was that unconscious motives and desires, fears and anxieties drive our actions. When upsetting memories or thoughts begin to find their way into our consciousness, we develop defenses to shield us from these painful realities. These defense mechanisms include denying a reality, repressing or pushing away painful thoughts, rationalization or finding a seemingly logical explanation for circumstances, projecting or attributing our feelings to someone else, or outwardly opposing something we inwardly desire (called reaction formation). Freud believed that many mental illnesses are a result of a person’s inability to accept reality. Freud emphasized the importance of early childhood experiences in shaping our personality and behavior. In our natural state, we are biological beings. We are driven primarily by instincts. During childhood, however, we begin to become social beings as we learn how to manage our instincts and transform them into socially acceptable behaviors. The type of parenting the child receives has a very power impact on the child’s personality development. We will explore this idea further in our discussion of psychosexual development.

Freud’s Theory of the Mind

Freud believed that most of our mental processes, motivations and desires are outside of our awareness. Our consciousness , that of which we are aware, represents only the tip of the iceberg that comprises our mental state. The preconscious represents that which can easily be called into the conscious mind. During development, our motivations and desires are gradually pushed into the unconscious because raw desires are often unacceptable in society.

Freud’s Theory of the Self

As adults, our personality or self consists of three main parts: the id , the ego and the superego . The id is the part of the self with which we are born. It consists of the biologically driven self and includes our instincts and drives. It is the part of us that wants immediate gratification. Later in life, it comes to house our deepest, often unacceptable desires such as sex and aggression. It operates under the pleasure principle which means that the criteria for determining whether something is good or bad is whether it feels good or bad. An infant is all id .  The ego is the part of the self that develops as we learn that there are limits on what is acceptable to do and that often, we must wait to have our needs satisfied. This part of the self is realistic and reasonable. It knows how to make compromises. It operates under the reality principle or the recognition that sometimes need gratification must be postponed for practical reasons. It acts as a mediator between the id and the superego and is viewed as the healthiest part of the self. [14]

The superego’s function is to control the id’s impulses, especially those which society forbids, such as sex and aggression. It also has the function of persuading the ego to turn to moralistic goals rather than simply realistic ones and to strive for perfection.

The superego consists of two systems: The conscience and the ideal self . The conscience can punish the ego through causing feelings of guilt. For example, if the ego gives in to the id’s demands, the superego may make the person feel bad through guilt.

The ideal self (or ego-ideal) is an imaginary picture of how you ought to be, and represents career aspirations, how to treat other people, and how to behave as a member of society.

Behavior which falls short of the ideal self may be punished by the superego through guilt. The super-ego can also reward us through the ideal self when we behave ‘properly’ by making us feel proud.  If a person’s ideal self is too high a standard, then whatever the person does will represent failure. The ideal self and conscience are largely determined in childhood from parental values and how you were brought up. [15]

Freud’s Levels of Consciousness in Relation to the Id, Ego, and Superego

Freud’s description of personality shows that the ego operates primarily at the conscious level, but also operates somewhat at both the preconscious and unconscious level as does the superego. However, the superego operates mostly at the unconscious level whereas the id totally functions at the unconscious level . [16]

Defense mechanisms emerge to help a person distort reality so that the truth is less painful. Defense mechanisms include repression which means to push the painful thoughts out of consciousness (in other words, think about something else). Denial is basically not accepting the truth or lying to the self. Thoughts such as “it won’t happen to me” or “you’re not leaving” or “I don’t have a problem with alcohol” are examples. Regression refers to going back to a time when the world felt like a safer place, perhaps reverting to one’s childhood. This is less common than the first two defense mechanisms. Sublimation involves transforming unacceptable urges into more socially acceptable behaviors. For example, a teenager who experiences strong sexual urges uses exercise to redirect those urges into more socially acceptable behavior. Displacement involves taking out frustrations on to a safer target. A person who is angry at a boss may take out their frustration at others when driving home or at a spouse upon arrival. Projection is a defense mechanism in which a person attributes their unacceptable thoughts onto others. If someone is frightened, for example, he or she accuses someone else of being afraid. Finally, reaction formation is a defense mechanism in which a person outwardly opposes something they inwardly desire, but that they find unacceptable. An example of this might be homophobia or a strong hatred and fear of homosexuality. This is a partial listing of defense mechanisms suggested by Freud. If the ego is strong, the individual is realistic and accepting of reality and remains more logical, objective, and reasonable. Building ego strength is a major goal of psychoanalysis (Freudian psychotherapy). So, for Freud, having a big ego is a good thing because it does not refer to being arrogant, it refers to being able to accept reality.

The superego is the part of the self that develops as we learn the rules, standards, and values of society. This part of the self takes into account the moral guidelines that are a part of our culture. It is a rule-governed part of the self that operates under a sense of guilt (guilt is a social emotion-it is a feeling that others think less of you or believe you to be wrong). If a person violates the superego, he or she feels guilty. The superego is useful but can be too strong; in this case, a person might feel overly anxious and guilty about circumstances over which they had no control. Such a person may experience high levels of stress and inhibition that keeps them from living well. The id is inborn, but the ego and superego develop during the course of our early interactions with others. These interactions occur against a backdrop of learning to resolve early biological and social challenges and play a key role in our personality development.

Psychosexual Stages

Freud’s psychosexual stages of development are presented in the table below. At any of these stages, the child might become “stuck” or fixated if a caregiver either overly indulges or neglects the child’s needs. A fixated adult will continue to try and resolve this later in life. Examples of fixation are given after the presentation of each stage.

Freud’s Psychosexual Stages

During the anal stage which coincides with toddlerhood or mobility and potty-training, the child is taught that some urges must be contained, and some actions postponed. There are rules about certain functions and when and where they are to be carried out. The child is learning a sense of self-control. The ego is being developed.  If the caregiver is extremely controlling about potty training (stands over the child waiting for the smallest indication that the child might need to go to the potty and immediately scoops the child up and places him on the potty chair, for example), the child may grow up fearing losing control. He may become fixated in this stage or “anal retentive” -fearful of letting go. Such a person might be extremely neat and clean, organized, reliable, and controlling of others. If the caregiver neglects to teach the child to control urges, he may grow up to be “ anal expulsive ” or an adult who is messy, irresponsible, and disorganized.

The Phallic stage occurs during the preschool years (ages 3-5) when the child has a new biological challenge to face. Freud believed that the child becomes sexually attracted to his or her opposite sexed parent. Boys experience the “ Oedipal Complex ” in which they become sexually attracted to their mothers but realize that Father is in the way. He is much more powerful. For a while, the boy fears that if he pursues his mother, father may castrate him ( castration anxiety ). So rather than risking losing his penis, he gives up his affections for his mother and instead learns to become more like his father, imitating his actions and mannerisms and thereby learns the role of males in his society. From this experience, the boy learns a sense of masculinity. He also learns what society thinks he should do and experiences guilt if he does not comply. In this way, the superego develops. If he does not resolve this successfully, he may become a “phallic male” or a man who constantly tries to prove his masculinity (about which he is insecure) by seducing women and beating up men! A little girl experiences the “ Electra Complex ” in which she develops an attraction for her father but realizes that she cannot compete with mother and so gives up that affection and learns to become more like her mother. This is not without some regret, however. Freud believed that the girl feels inferior because she does not have a penis (experiences “ penis envy ”). But she must resign herself to the fact that she is female and will just have to accept her inferior role in society as a female.  However, if she does not resolve this conflict successfully, she may have a weak sense of femininity and grow up to be a “castrating female” who tries to compete with men in the workplace or in other areas of life.

During middle childhood (6-11), the child enters the latency stage focusing his or her attention outside the family and toward friendships. The biological drives are temporarily quieted (latent) and the child can direct attention to a larger world of friends. If the child is able to make friends, he or she will gain a sense of confidence. If not, the child may continue to be a loner or shy away from others, even as an adult.

The final stage of psychosexual development is referred to as the genital stage . From adolescence throughout adulthood a person is preoccupied with sex and reproduction.  The adolescent experiences rising hormone levels and the sex drive and hunger drives become very strong. Ideally, the adolescent will rely on the ego to help think logically through these urges without taking actions that might be damaging. An adolescent might learn to redirect their sexual urges into safer activity such as running, for example. Quieting the id with the superego can lead to feeling overly self-conscious and guilty about these urges. Hopefully, it is the ego that is strengthened during this stage and the adolescent uses reason to manage urges.

Strengths and Weaknesses of Freud’s Theory

Freud’s theory has been heavily criticized for several reasons. One is that it is very difficult to test scientifically. How can parenting in infancy be traced to personality in adulthood? Are there other variables that might better explain development? The theory is also considered to be sexist in suggesting that women who do not accept an inferior position in society are somehow psychologically flawed. Freud focuses on the darker side of human nature and suggests that much of what determines our actions is unknown to us. So why do we study Freud? As mentioned above, despite the criticisms, Freud’s assumptions about the importance of early childhood experiences in shaping our psychological selves have found their way into child development, education, and parenting practices. Freud’s theory has heuristic value in providing a framework from which elaborate and modify subsequent theories of development. Many later theories, particularly behaviorism and humanism, were challenges to Freud’s views. [17]

Erik Erikson (1902-1994) and Psychosocial Theory [18]

Erikson suggested that our relationships and society’s expectations motivate much of our behavior in his theory of psychosocial development . Erikson was a student of Freud’s but emphasized the importance of the ego, or conscious thought, in determining our actions. In other words, he believed that we are not driven by unconscious urges. We know what motivates us and we consciously think about how to achieve our goals. He is considered the father of developmental psychology because his model gives us a guideline for the entire life span and suggests certain primary psychological and social concerns throughout life.

Erikson expanded on his Freud’s by emphasizing the importance of culture in parenting practices and motivations and adding three stages of adult development (Erikson, 1950; 1968).

He believed that we are aware of what motivates us throughout life and the ego has greater importance in guiding our actions than does the id. We make conscious choices in life and these choices focus on meeting certain social and cultural needs rather than purely biological ones. Humans are motivated, for instance, by the need to feel that the world is a trustworthy place, that we are capable individuals, that we can make a contribution to society, and that we have lived a meaningful life. These are all psychosocial problems.

Erikson divided the lifespan into eight stages. In each stage, we have a major psychosocial task to accomplish or crisis to overcome. Erikson believed that our personality continues to take shape throughout our lifespan as we face these challenges in living. Here is a brief overview of the eight stages:

Erik Erikson’s Psychosocial Theory

These eight stages form a foundation for discussions on emotional and social development during the life span. Keep in mind, however, that these stages or “crises” can occur more than once. For instance, a person may struggle with a lack of trust beyond infancy under certain circumstances. Erikson’s theory has been criticized for focusing so heavily on stages and assuming that the completion of one stage is prerequisite for the next crisis of development. His theory also focuses on the social expectations that are found in certain cultures, but not in all. For instance, the idea that adolescence is a time of searching for identity might translate well in the middle-class culture of the United States, but not as well in cultures where the transition into adulthood coincides with puberty through rites of passage and where adult roles offer fewer choices. [19]

Learning Theories

While Freud and Erikson looked at what was going on in the mind, learning theories  rejected any reference to mind and viewed overt and observable behavior as the proper subject matter of psychology. Through the scientific study of behavior, it was hoped that laws of learning could be derived that would promote the prediction and control of behavior. [20]

Ivan Pavlov (1870-1937) and Classical Conditioning [21] and Classical Conditioning with Animals

Ivan Pavlov was a Russian physiologist interested in studying digestion. As he recorded the amount of salivation his laboratory dogs produced as they ate, he noticed that they began to salivate before the food arrived as the researcher walked down the hall and toward the cage. “This,” he thought, “is not natural!” One would expect a dog to automatically salivate when food hit their palate, but BEFORE the food comes? Of course, what had happened was . . . you tell me. That’s right! The dogs knew that the food was coming because they had learned to associate the footsteps with the food. The key word here is “learned”. A learned response is called a “conditioned” response.

Pavlov began to experiment with this concept of classical conditioning . He began to ring a bell, for instance, prior to introducing the food. Sure enough, after making this connection several times, the dogs could be made to salivate to the sound of a bell. Once the bell had become an event to which the dogs had learned to salivate, it was called a conditioned stimulus . The act of salivating to a bell was a response that had also been learned, now termed in Pavlov’s jargon, a conditioned response . Notice that the response, salivation, is the same whether it is conditioned or unconditioned (unlearned or natural). What changed is the stimulus to which the dog salivates. One is natural (unconditioned) and one is learned (conditioned).

Summary of Classical Conditioning Process (Animals)

Pavlovian Conditioning of a dog to salivate upon hearing a bell.

To summarize, classical conditioning (later developed by Watson, 1913) involves learning to associate an unconditioned stimulus that already brings about a particular response (i.e., a reflex) with a new (conditioned) stimulus, so that the new stimulus brings about the same response.

Pavlov developed some rather unfriendly technical terms to describe this process. The unconditioned stimulus (or UCS) is the object or event that originally produces the reflexive /natural response.  The response to this is called the unconditioned response (or UCR). The neutral stimulus (NS) is a new stimulus that does not produce a response.  Once the neutral stimulus has become associated with the unconditioned stimulus, it becomes a conditioned stimulus (CS). The conditioned response (CR) is the response to the conditioned stimulus. [22]

Now, let’s think about how classical conditioning is used on us. One of the most widespread applications of classical conditioning principles was brought to us by the psychologist, John B. Watson. [23]

John B. Watson (1878-1958) and Classical Conditioning [24] and Classical Conditioning in Humans

Watson believed that most of our fears and other emotional responses are classically conditioned. He had gained a good deal of popularity in the 1920s with his expert advice on parenting offered to the public.  He tried to demonstrate the power of classical conditioning with his famous experiment with an 18-month-old boy named “Little Albert”. Watson sat Albert down and introduced a variety of seemingly scary objects to him: a burning piece of newspaper, a white rat, etc. But Albert remained curious and reached for all of these things. Watson knew that one of our only inborn fears is the fear of loud noises so he proceeded to make a loud noise each time he introduced one of Albert’s favorites, a white rat. After hearing the loud noise several times paired with the rat, Albert soon came to fear the rat and began to cry when it was introduced. Watson filmed this experiment for posterity and used it to demonstrate that he could help parents achieve any outcomes they desired, if they would only follow his advice. Watson wrote columns in newspapers and in magazines and gained a lot of popularity among parents eager to apply science to household order. [25]

Summary of Classical Conditioning Process (Humans)

Watson’s conditioning of Little Albert to fear a white rat. [26]

Operant conditioning, on the other hand, looks at the way the consequences of a behavior increase or decrease the likelihood of a behavior occurring again. So, let’s look at this a bit more. [27]

B.F. Skinner (1904-1990) and Operant Conditioning [28] and Operant Conditioning in Animals and Humans

Skinner (1904-1990), who brought us the principles of operant conditioning , suggested that reinforcement is a more effective means of encouraging a behavior than is punishment. By focusing on strengthening desirable behavior, we have a greater impact than if we emphasize what is undesirable.

Reinforcement is the process by which a consequence increases the probability of a behavior that it follows. A reinforcer is a specific stimulus or situation that encourages the behavior that it follows. Intrinsic or primary reinforcers are reinforcers that have innate reinforcing qualities. These kinds of reinforcers are not learned and satisfy a biological need. Water, food, sleep, shelter, sex, pleasure, and touch, among others, are primary reinforcers. Swimming in a cool lake on a very hot day would be innately reinforcing because the water would cool the person off (a physical need), as well as provide pleasure.  Extrinsic or secondary reinforcers have no inherent value and only have reinforcing qualities when linked with primary reinforcers.  They can be traded in for what is ultimately desired.  Praise, when linked to affection, is one example of a secondary reinforcer.  Another example is money, which is only worth something when you can use it to buy other things—either things that satisfy basic needs (food, water, shelter—all primary reinforcers) or other secondary reinforcers.   Extrinsic or secondary reinforcers are things that have a value not immediately understood.

Positive reinforcement occurs when the addition of a stimulus strengthens behavior.  For example,  positively reinforcing a child with the addition of a cookie for cleaning up will likely make encourage that behavior in the future.  Negative reinforcement , on the other hand, occurs when removing a desired stimulus (or preventing access to it) strengthens behavior. For example, an alarm clock makes a very unpleasant, loud sound when it goes off in the morning. As a result, one gets up and turns it off.  Therefore, getting up from bed is negatively reinforced through the termination of the aversive sound.

Punishment is the process by which there decrease in the probability of behavior as a result of the consequence that follows it.  Positive punishment occurs when the addition of an unpleasant or painful stimulus weakens behavior.  For example, if a child is naughty and receives a spanking, the child will be less likely to misbehave in the future.   Negative punishment, on the other hand, weakens a behavior through the removal of a desirable stimulus or preventing access to it.  For example, a child who misbehaves and as a result has their favorite toy will be less likely to misbehave in the future.   Punishment is often less effective than reinforcement for several reasons. It doesn’t indicate the desired behavior, it may result in suppressing rather than stopping a behavior, (in other words, the person may not do what is being punished when you’re around, but may do it often when you leave), and a focus on punishment can result in not noticing when the person does well.

Examples of Operant Conditioning Using Positive and Negative Reinforcement and Positive and Negative Punishers

Not all behaviors are learned through association or reinforcement. Many of the things we do are learned by watching others. This is addressed in social learning theory. [29]

Schedules of Reinforcement

Imagine a rat in a “Skinner box.” In operant conditioning, if no food pellet is delivered immediately after the lever is pressed then after several attempts the rat stops pressing the lever (how long would someone continue to go to work if their employer stopped paying them?). The behavior has been extinguished.

Behaviorists discovered that different patterns or schedules of reinforcement had different effects on the speed of learning and extinction. Ferster and Skinner (1957) devised different ways of delivering reinforcement and found that this had effects on

• The Response Rate – The rate at which the rat pressed the lever (i.e., how hard the rat worked).
• The Extinction Rate – The rate at which lever pressing dies out (i.e., how soon the rat gave up).

Skinner found that the type of reinforcement which produces the slowest rate of extinction (i.e., people will go on repeating the behavior for the longest time without reinforcement) is variable-ratio reinforcement . The type of reinforcement which has the quickest rate of extinction is continuous reinforcement.

Continuous Reinforcement :

An animal/human is positively reinforced every time a specific behavior occurs, e.g., every time a lever is pressed a pellet is delivered, and then food delivery is shut off.

Response rate is SLOW

Extinction rate is FAST

Fixed Ratio Reinforcement :

Behavior is reinforced only after the behavior occurs a specified number of times. e.g., one reinforcement is given after every so many correct responses, e.g., after every 5th response. For example, a child receives a star for every five words spelled correctly.

Response rate is FAST

Extinction rate is MEDIUM

Fixed Interval Reinforcement :

One reinforcement is given after a fixed time interval providing at least one correct response has been made. An example is being paid by the hour. Another example would be every 15 minutes (half hour, hour, etc.) a pellet is delivered (providing at least one lever press has been made) then food delivery is shut off.

Response rate is MEDIUM

Variable Ratio Reinforcement :

Behavior is reinforced after an unpredictable number of times. For examples gambling or fishing.

Extinction rate is SLOW (very hard to extinguish because of unpredictability)

Variable Interval Reinforcement :

Providing one correct response has been made, reinforcement is given after an unpredictable amount of time has passed, e.g., on average every 5 minutes. An example is a self-employed person being paid at unpredictable times.

Extinction rate is SLOW [30]

Graphic Representation of Schedules of Reinforcement

Each dash indicates the point where reinforcement is given. [31]

Applied Behavior Analysis

Applied behavior analysis (ABA) , also known as behavior modification, is based on the application of experimental analysis of behavior findings to create meaningful behavior change in children and adults; thereby improving their well-being.  ABA consists of a set of therapies/techniques based on operant conditioning principles (Skinner, 1938, 1953). The main principle comprises changing environmental events that are related to a person’s behavior such as the reinforcement of desired behaviors and the extinction of undesired ones.

Techniques in ABA:  Token Economy

One type of applied behavioral analytic technique is the token economy which is frequently used in institutional settings.  Tokens, generally in the form of fake money, buttons, poker chips, stickers, etc., can be exchanged for special foods, television time, activities, or other positive reinforcers.  For example, teachers use token economies at primary schools by giving young children stickers to reinforce good behavior.  Token economies have also been found to be very effective in the management of behavior in people staying in psychiatric hospitals.

Techniques in ABA:  Shaping

A further important technique proposed by Skinner (1951) is the concept of shaping . Skinner argues that shaping can be used to produce extremely complex behavior through the differential reinforcement of successive approximations towards that terminal behavior.  Upon the successful completion of each behavior in the chain, the contingencies of reinforcement become more stringent.  That is, the organism only is reinforced upon the completion of all previous steps plus the next step in the behavior chain.  Reinforcement must be discontinued for the previous step(s) in order to propel the organism forward to the terminal behavior.  According to Skinner, most animal and human behavior (including language) can be explained through shaping.

Educational Application of Applied Behavior Analysis

A simple way to shape behavior in the classroom is to provide feedback on learner performance, e.g., compliments, approval, encouragement, and affirmation.  For example, if a teacher wanted to encourage students to answer questions in class the teacher should praise them for every attempt (regardless of whether their answer is correct). Gradually the teacher will only praise the students when their answer is correct, and over time only exceptional answers will be praised.  Unwanted behaviors, such as tardiness and dominating class discussion can be extinguished through the discontinuation of reinforcement by the teacher (i.e., the teacher will stop reinforcing attention-seeking behaviors).  Desirable behaviors can be maintained by varying reinforcers. [32]

Albert Bandura (1925-2021) and Social Learning Theory [33] and Social Learning Theory

Albert Bandura is a leading contributor to social learning theory . He calls our attention to the ways in which many of our actions are not learned through conditioning; rather, they are learned by watching others (1977). Young children frequently learn behaviors through imitation .

Sometimes, particularly when we do not know what else to do, we learn by observing others model their behavior and then imitating or copying that behavior. A kindergartner on his or her first day of school might eagerly look at how others are acting and try to act the same way to fit in more quickly. Adolescents struggling with their identity rely heavily on their peers to act as role-models. Sometimes we do things because we’ve seen it pay off for someone else. They were operantly conditioned, but we engage in the behavior because we hope it will pay off for us as well. This is referred to as vicarious reinforcement (Bandura, Ross and Ross, 1963).

Bandura (1986) suggests that there is interplay between the environment and the individual. We are not just the product of our surroundings, rather we influence our surroundings. Parents not only influence their child’s environment, perhaps intentionally through the use of reinforcement, etc., but children influence parents as well. Parents may respond differently with their first child than with their fourth. Perhaps they try to be the perfect parents with their firstborn, but by the time their last child comes along they have very different expectations both of themselves and their child. Our environment creates us, and we create our environment. [34]

Cognitive Developmental Theories

Jean piaget (1896-1980) and theory of cognitive development [37].

Jean Piaget is one of the most influential cognitive theorists, and in Chapter 7 we will discuss his work and his legacy in much more detail. Piaget was inspired to explore children’s ability to think and reason by watching his own children’s development. He was one of the first to recognize and map out the ways in which children’s thought differs from that of adults. His interest in this area began when he was asked to test the IQ of children and began to notice that there was a pattern in their wrong answers. He believed that children’s intellectual skills change over time through maturation. Children of differing ages interpret the world differently.

Piaget believed our desire to understand the world comes from a need for cognitive equilibrium. This is an agreement or balance between what we sense in the outside world and what we know in our minds. If we experience something that we cannot understand, we try to restore the balance by either changing our thoughts or by altering the experience to fit into what we do understand. Perhaps you meet someone who is very different from anyone you know. How do you make sense of this person? You might use them to establish a new category of people in your mind or you might think about how they are similar to someone else.

A schema or schemes are categories of knowledge. They are like mental boxes of concepts. A child has to learn many concepts. They may have a scheme for “under” and “soft” or “running” and “sour”. All of these are schema. Our efforts to understand the world around us lead us to develop new schema and to modify old ones.

One way to make sense of new experiences is to focus on how they are similar to what we already know. This is assimilation . So, the person we meet who is very different may be understood as being “sort of like my brother” or “his voice sounds a lot like yours.” Or a new food may be assimilated when we determine that it tastes like chicken!

Another way to make sense of the world is to change our mind. We can make a cognitive accommodation to this new experience by adding new schema. This food is unlike anything I’ve tasted before. I now have a new category of foods that are bitter-sweet in flavor, for instance. This is accommodation. Do you accommodate or assimilate more frequently? Children accommodate more frequently as they build new schema. Adults tend to look for similarity in their experience and assimilate. They may be less inclined to think “outside the box.”

Piaget suggested different ways of understanding that are associated with maturation. He divided this understanding into the following four stages which will be discussed in much more detail in Chapter 7:

Piaget’s Stages of Cognitive Development [38]

Criticisms of Piaget’s Theory

Piaget has been criticized for overemphasizing the role that physical maturation plays in cognitive development and in underestimating the role that culture and interaction (or experience) plays in cognitive development. Looking across cultures reveals considerable variation in what children are able to do at various ages. Piaget may have underestimated what children are capable of given the right circumstances. [39]

Lev Vygotsky (1896-1934) and Sociocultural Theory [40]

Lev Vygotsky was a Russian psychologist who wrote in the early 1900s but whose work was discovered in the United States in the 1960s but became more widely known in the 1980s. Vygotsky differed with Piaget (this difference will be discussed in more detail in Chapter 7) in that he believed that a person not only has a set of abilities, but also a set of potential abilities that can be realized if given the proper guidance from others. His sociocultural theory emphasizes the importance of culture and interaction in the development of cognitive abilities. He believed that through guided participation known as scaffolding , with a teacher or capable peer, a child can learn cognitive skills within a certain range known as the zone of proximal development . [41]

Have you ever taught a child to perform a task? Maybe it was brushing their teeth or preparing food. Chances are you spoke to them and described what you were doing while you demonstrated the skill and let them work along with you all through the process. You gave them assistance when they seemed to need it, but once they knew what to do-you stood back and let them go. This is scaffolding and can be seen demonstrated throughout the world. This approach to teaching has also been adopted by educators. Rather than assessing students on what they are doing, they should be understood in terms of what they are capable of doing with the proper guidance. You can see how Vygotsky would be very popular with modern day educators. [42]

Comparing Piaget and Vygotsky

Vygotsky concentrated more on the child’s immediate social and cultural environment and his or her interactions with adults and peers. While Piaget saw the child as actively discovering the world through individual interactions with it, Vygotsky saw the child as more of an apprentice, learning through a social environment of others who had more experience and were sensitive to the child’s needs and abilities. [43]

Information Processing

Information Processing is not the work of a single theorist but based on the ideas and research of several cognitive scientists studying how individuals perceive, analyze, manipulate, use, and remember information. This approach assumes that humans gradually improve in their processing skills; that is, cognitive development is continuous rather than stage-like. The more complex mental skills of adults are built from the primitive abilities of children. We are born with the ability to notice stimuli, store, and retrieve information. Brain maturation enables advancements in our information processing system. At the same time, interactions with the environment also aid in our development of more effective strategies for processing information. [44]

Urie Bronfenbrenner (1917-2005) and  Ecological Systems Theory [45]

Bronfenbrenner offers us one of the most comprehensive theories of human development. Bronfenbrenner studied Freud, Erikson, Piaget, and learning theorists and believed that all those theories could be enhanced by adding the dimension of context. What is being taught and how society interprets situations depends on who is involved in the life of a child and on when and where a child lives.  Bronfenbrenner’s ecological systems model explains the direct and indirect influences on an individual’s development. [46]   The individual is impacted by several systems including:

• Microsystem includes the individual’s setting and those who have direct, significant contact with the person, such as parents or siblings. The input of those is modified by the cognitive and biological state of the individual as well. These influence the person’s actions, which in turn influence systems operating on him or her.
• Mesosystem includes the larger organizational structures, such as school, the family, or religion. These institutions impact the microsystems just described. The philosophy of the school system, daily routine, assessment methods, and other characteristics can affect the child’s self-image, growth, sense of accomplishment, and schedule thereby impacting the child, physically, cognitively, and emotionally.
• Exosystem includes the larger contexts of community. A community’s values, history, and economy can impact the organizational structures it houses. Mesosystems both influence and are influenced by the exosystem.
• Macrosystem includes the cultural elements, such as global economic conditions, war, technological trends, values, philosophies, and a society’s responses to the global community.
• Chronosystem is the historical context in which these experiences occur. This relates to the different generational time periods previously discussed, such as the baby boomers and millennials.

In sum, a child’s experiences are shaped by larger forces, such as the family, schools, religion, culture, and time period. Bronfenbrenner’s model helps us understand all the different environments that impact each one of us simultaneously. Despite its comprehensiveness, Bronfenbrenner’s ecological system’s theory is not easy to use. Taking into consideration all the different influences makes it difficult to research and determine the impact of all the different variables (Dixon, 2003). Consequently, psychologists have not fully adopted this approach, although they recognize the importance of the ecology of the individual. [47]

Bronfenbrenner’s Ecological Systems Theory [48]

Esther Thelen and Dynamic Systems Theory [49]

The dominant view of motor development for much of the 20th century was that the development of action occurred in a series of relatively fixed motor milestones. The emphasis was on normative development, the concept of motor programs that controlled action, and a sequence of milestones that was largely under genetic or biological control (for review, see Adolph & Berger, 2006). The landscape has shifted dramatically in the last 20 years, thanks in large part to the work of Esther Thelen (as well as other systems thinkers, most notably, Gibson, 1988; see Adolph & Berger, 2006). Today the field views motor development as emergent and exploratory with a new emphasis on individual development in context. Although this revolution in thinking was spurred by dynamic systems concepts, it was also driven forward by a wealth of empirical research.

For instance, Esther Thelen conducted a now-classic set of studies investigating the early disappearance of the stepping reflex. Thelen’s early work on stepping revealed that the coordination patterns that underlie stepping and kicking were strikingly similar. The puzzle was that newborn stepping disappeared within the first three months, whereas kicking continued and increased in frequency. To explain the disappearance of stepping, several researchers had proposed that maturing cortical centers inhibit the primitive stepping reflex or that stepping was phylogenetically programmed to disappear (e.g., Andre-Thomas & Autgaerden, 1966).

To probe the mystery of the disappearing steps, Thelen conducted a longitudinal study that focused on the detailed development of individual infants. Thelen, Fisher, and Ridley-Johnson (1984) found a clue in the fact that chubby babies and those who gained weight fastest were the first to stop stepping. This led to the hypothesis that it requires more strength for young infants to lift their legs when upright (in a stepping position) than when lying down (in a kicking position). To test this idea, Thelen and colleagues conducted two ingenious studies. In one, they placed small leg weights on two-month-old babies, similar in amount to the weight they would gain in the ensuing month. This significantly reduced stepping. In the other, they submerged older infants whose stepping had begun to wane in water up to chest levels. Robust stepping now reappeared. These data demonstrated that traditional explanations of neural maturation and innate capacities were insufficient to explain the emergence of new patterns and the flexibility of motor behavior.

Since this seminal work, Thelen and her colleagues have intensively examined the development of alternating leg movements (Thelen & Ulrich, 1991), the emergence of crawling (Adolph, Vereijken, & Denny, 1988), the emergence of walking (e.g., Adolph, 1997; Thelen & Ulrich, 1991), and the development of reaching (Corbetta, Thelen, & Johnson, 2000; Thelen, Corbetta & Spencer, 1996; Thelen et al., 1993). In all cases, these researchers have shown that new action patterns emerge in the moment from the self-organization of multiple components. The stepping studies elegantly illustrated this, showing how multiple factors cohere in a moment in time to create or hinder leg movements. And, further, these studies illustrate how changes in the components of the motor system over the longer time scale of development interact with real-time behavior. [50]

Many early theories of human development were created and popularized in the early 1900s. These are referred to as stage theories because they present development as occurring in stages. The assumption is that once one stage is completed, a person moves into the next stage and that stages tend to occur only once. Some examples of stage theories that we will be studying include Freud’s psychosexual stages, Erikson’s psychosocial stages, and Piaget’s stages of cognitive development, to name a few.

These theories are appealing in a way because they provide the ability to predict what will happen next and they allow us to attribute behavior to a person’s being ‘in a stage’. These theories offered the security of understanding human behavior in a time of rapid change during industrialization in the early 1900s. Science seemed to be laying a predictable groundwork we could rely upon. But these early theories also implied that those who did not progress through stages in the predictable way were delayed somehow and this led to the idea that development had to occur in a patterned way.

Today we understand that development does not occur in a straight line. Sometimes we change in many directions depending on our experiences and surroundings. For example, there can be growth and decline in cognitive functioning at any age depending on nutrition, health, activity, and stimulation. And that both nature (heredity) and nurture (the environment) shape our abilities throughout life. Some things about us are continuous such as our temperament or sense of self, perhaps. And we may revisit a stage of life more than once. For instance, Erikson suggests that we struggle with trust as infants and then begin to focus more on independence or autonomy. But if we are in circumstances in which our independence is jeopardized, such as becoming physically dependent, we may struggle with trust again. Keep these thoughts in mind as we explore stage theories in our next lesson.

The study of human development is based on research. The next chapter looks at some of the different types of research methods used to understand development. In other words, how do we know what we know? [51]

Test Yourself: Review of  Theories of Childhood Development

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The development of physical changes, such as the development of fine and gross motor skills.

The development of such things as memory and the ability to incorporate new information.

The ability manage and control expressions of emotion.

Relating to multiple contexts.

The genetically determined characteristics and behaviors of an individual.

The environmental factors that influence development and behavior.

Anything that can lead to developmental abnormalities in the developing fetus or embryo.

The dispute over the contributions of heredity (nature) and the environment (nurture) to the development of an individual.

The viewpoint that development takes place as specific steps or stages.

Development is seen as a cumulative process that gradually takes place and improves on existing skill sets.

A set of supported hypotheses that have been tested using empirical facts and is used to predict, explain, and understand behaviors.

Locke's conception that all knowledge comes from sensory experiences from the environment.

The branch of medicine that deals with the nervous system (the brain, digestion, breathing, and sexual development)

the historical name for the condition now largely classified as conversion disorder but with symptoms dispersed across other formal diagnoses as well (e.g., histrionic personality disorder). Although technically outdated, it is often used as a lay term for any psychogenic disorder characterized by symptoms such as paralysis, blindness, loss of sensation, and hallucinations and often accompanied by suggestibility, emotional outbursts, and histrionic behavior.

the region of the psyche containing memories, emotional conflicts, wishes, and repressed impulses that are not directly accessible to awareness but that have dynamic effects on thought and behavior.

an unconscious reaction pattern employed by the ego to protect itself from the anxiety that arises from psychic conflict.

the region of the psyche that contains thoughts, feelings, perceptions, and other aspects of mental life currently present in awareness.

refers to something that one is not currently aware of but could be brought into consciousness at any given moment.

The personality component made up of unconscious psychic energy that works to satisfy basic urges, needs, and desires.

That portion of the human personality which is in contact with the external world through perception. It is the part that remembers, evaluates, plans, and in other ways is responsive to and acts in the surrounding physical and social world.

The moral component of the personality that represents parental and societal standards and determines personal standards of right and wrong, or conscience, as well as aims and aspirations

the psychic force that motivates people to seek immediate gratification of instinctual, or libidinal, impulses, such as sex, hunger, thirst, and elimination. It dominates the id and operates most strongly during childhood.

the regulatory mechanism that represents the demands of the external world and requires the individual to forgo or modify instinctual gratification or to postpone it to a more appropriate time.

the ethical component of personality, which acts as judge and critic of one’s actions and attitudes.

the inner image of oneself as one wants to become, and the image by which one measures their actual self.

The conscious refusal to perceive that painful facts exist

An unconscious defense mechanism, which causes the temporary or long-term reversion of the ego to an earlier stage of development (instead of handling unacceptable impulses in a more adult manner).

a defense mechanism in which unacceptable sexual or aggressive drives are unconsciously channeled into socially acceptable behaviors.

the transfer of feelings or behavior from their original object to less threatening target.

a defense mechanism in which unpleasant or unacceptable impulses, stressors, ideas, affects, or responsibilities are attributed to others.

a defense mechanism in which unacceptable or threatening unconscious impulses are denied and are replaced in consciousness with their opposite.

the inappropriate attachment to an early psychosexual object or mode of gratification, such as anal or oral activity.

the first stage of psychosexual development, occupying the 1st year of life, in which the libido is concentrated on the mouth as the principal erotic zone.

the second stage of psychosexual development, typically occurring during the 2nd year of life, in which the child’s interest and sexual pleasure are focused on the expulsion and retention of feces

excessively orderly and fussy (supposedly owing to conflict over toilet-training in infancy).

Indicating personality traits, such as conceit, ambition, and generosity, originating in habits, attitudes, or values associated with infantile pleasure in the expulsion of feces.

the third stage of psychosexual development beginning around age 3, when the libido is focused on the genital area (penis or clitoris) and discovery and manipulation of the body become a major source of pleasure.

(in Freudian theory) the complex of emotions aroused in a young child, typically around the age of four, by an unconscious sexual desire for the parent of the opposite sex and wish to exclude the parent of the same sex.

fear of injury to or loss of the genitals.

a term used to describe the female version of the Oedipus complex, where a young girl becomes subconsciously sexually attached to her father and increasingly hostile toward her mother.

the hypothesized desire of girls and women to possess the male genital organ.

the stage of psychosexual development in which overt sexual interest is sublimated and the child’s attention is focused on skills and peer activities with members of his or her own sex.

the final stage of psychosexual development, where sexual interest and activity are focused on intercourse with a sexual partner.

according to Erik Erikson, personality development as a process influenced by social and cultural factors throughout the lifespan.

a type of learning in which an initially neutral stimulus—the conditioned stimulus (CS)—when paired with a stimulus that elicits a reflex response—the unconditioned stimulus (US)—results in a learned, or conditioned, response (CR) when the CS is presented.

a neutral stimulus that is repeatedly associated with an unconditioned stimulus until it acquires the ability to elicit a response that it previously did not.

the learned or acquired response to a conditioned stimulus.

a stimulus that elicits an unconditioned response, as in salivation when food is in the mouth.

the unlearned response to a stimulus (e.g., salivation in response to the presentation of food).

a stimulus that does not elicit a response of the sort to be measured as an index of conditioning. For example, the sound of a bell has no effect on salivation, therefore it is a neutral stimulus with respect to salivation.

the process where learning occurs as a result of the consequences of behavior.

the process whereby the probability of a response increases based on its contingency with a stimulus or circumstance.

a stimulus or situation that produces reinforcement when it occurs.

reinforcers that occur naturally and do not need to be learned, for example food, water, sleep and sex.

a stimulus that reinforces a behavior after it has been associated with a primary reinforcer, for example, money.

The introduction of a stimulus that will likely increase the probability of behavior.

the removal of a stimulus or situation after a behavior that will potentially result in a likely increase of the behavior.

any change in behavior that occurs after that behavior reduces the likelihood of repeating that behavior.

rules that are used to present and remove reinforcers following a specified operant behavior.

a type of reinforcement schedule that reinforces the target behavior after an unpredictable number of responses.

a schedule whereby reinforcement is delivered after the completion of a specific number of responses.

a schedule of reinforcement where the first response is rewarded only after a specified amount of time has elapsed.

a schedule of reinforcement where a response is rewarded after an unpredictable amount of time has passed.

the extension of B. F. Skinner’s behavioral principles (i.e., operant conditioning) to practical settings. Variations of applied behavior analysis may be used clinically (in the form of behavior modification or behavior therapy) as treatment for abnormal or problematic behaviors.

an approach to experimental psychology that explores the relationships between particular experiences and changes in behavior, emphasizing the behavior of individuals rather than group averages. It is concerned especially with describing how contingencies of reinforcement control the rate of an instrumental response.

a program where desired behaviors are reinforced by offering tokens that can be exchanged for rewards.

the production of new forms of operant behavior by reinforcement of successive approximations to the behavior. (Also referred to as the method of successive approximations)

the general view that learning is largely or wholly due to modeling, imitation, and other social interactions.

an observer repeats the behavior that is performed by a model

the process in which one or more individuals serve as examples (models) that a child will imitate. Models are often parents, other adults, or other children, but they may also be symbolic (e.g., a book or television character)

a collection of basic knowledge about a concept that serves as a guide to perception, interpretation, imagination, or problem solving.

the cognitive process whereby we fit new information readily into our existing knowledge or shema.

altering one's existing schema or knowledge as a result of new information or new experiences.

stresses the idea that the ways people interact with others and the culture they live in shape their mental abilities.

teaching material that is just beyond the level at which at which a student could learn on their own without the help of another.

the difference between a child's actual level of ability and the level of ability that he or she can reach with the help of an experienced "other."

describes the individuals, groups, and institutions that directly influence a child's development.

where a person's individual microsystems do not function independently, but are interconnected and assert influence upon one another. For instance, if a child's parents communicate with the child's teachers, this interaction may influence the child's development.

refers to the parts of the environment which impact an individual's development, even though they do not directly interact with the individual

focuses on how cultural elements affect a child's development, such as socioeconomic status, wealth, poverty, and ethnicity.

all of the experiences that a person has had during his or her lifetime, including environmental events, major life transitions, and historical events.

Infant and Child Development: From Conception Through Late Childhood Copyright © by Marie Parnes and Maria Pagano is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

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Case Study of the Development of an Infant with Autism from Birth to Two Years of Age

Affiliation.

• 1 University of Washington.
• PMID: 23667283
• PMCID: PMC3650850
• DOI: 10.1016/S0193-3973(99)00042-8

This report describes a case study of the development of an infant with autism who was observed closely by professionals from birth and to whom a comprehensive psychological evaluation was administered at approximately 1 and 2 years of age. During the first 6 months of life, this infant displayed difficulties in oral motor coordination and muscle tone that fluctuated between hypotonia and hypertonia. He startled easily, had poor state regulation, and was hypersensitive to touch. Notably, however, during the first 6 months, this infant vocalized and responded socially to others by smiling and cooing. During the second half of the first year, he continued to demonstrate diffuse sensorimotor difficulties and diminished oral motor control. Hypersensitivity now extended to a wider range of stimuli. He had problems in sleep regulation. Motor stereotypies, including rocking, head banging, and toe walking, were observed. Difficulties in the domain of social interaction began to emerge during the second 6 months, including poor eye contact, failure to engage in imitative games, and lack of imitative vocal responses. By a little over 1 year of age, this infant met diagnostic criteria for autism based on the Autism Diagnostic Interview. There were several domains in which this toddler with autism did not show impairments. In the areas of immediate memory for actions, working memory, response inhibition, and speech perception, this 1-year old with autism displayed no evidence of significant impairment on the tests administered. This case study offers clues regarding the nature of autism at its earliest stages. Understanding early development in autism will be important for developing early screening and diagnostic tools.

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Media Advisory: Atypical metabolite levels at birth may increase SIDS risk

Nih-funded study suggests checking for metabolite pattern at birth could provide means to estimate sids risk.

Newborns who had an atypical pattern of metabolites were more than 14 times as likely to die of sudden infant death syndrome ( SIDS ), compared to infants who had more typical metabolic patterns, according to a study funded in part by the National Institutes of Health. Metabolites are molecules produced by the body’s various chemical reactions. Researchers found that infants who died of SIDS had a specific pattern of metabolites compared to infants who lived to their first year. The researchers believe that checking for this pattern could provide a way to identify infants at risk for SIDS. The study was conducted by Scott Oltman, M.S., of the University of California San Francisco School of Medicine, and colleagues. It appears in JAMA Pediatrics .

SIDS is the sudden, unexplained death of an infant younger than 1 year of age that remains unexplained after a complete investigation. From more than 2 million infants born in California, researchers compared newborn screening test results of 354 SIDS cases to those of 1,416 infants who survived to at least one year old. The state screens all its newborns for many serious disorders. Test results include checking for metabolites that are markers for disorders and conditions. In the study, infants identified with the highest risk metabolic profile involving eight metabolites were 14.4 times more likely to have SIDS than infants with the lowest risk metabolic profile.

The authors say that testing for metabolic patterns may provide a way to identify infants at risk for SIDS soon after birth, which could inform efforts to reduce SIDS risk. Similarly, research on the biochemical pathways that produce the metabolites linked to SIDS may yield insights into the causes of SIDS and ways to reduce its risk. NIH funding for the study was provided by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD).

Marion Koso Thomas, M.D., of the NICHD Pregnancy and Perinatology Branch, is available for comment.

Oltman, SP. Early Newborn Metabolic Patterning and Sudden Infant Death Syndrome. JAMA Pediatrics. 2024. DOI: 10.1001/jamapediatrics.2024.3033

About the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) : NICHD leads research and training to understand human development, improve reproductive health, enhance the lives of children and adolescents, and optimize abilities for all. For more information, visit https://www.nichd.nih.gov .

About the National Institutes of Health (NIH) : NIH, the nation's medical research agency, includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit https://www.nih.gov .

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Sustainable spatial development of multifunctional villages: a case study of eastern poland.

1. Introduction

Spatial characteristics of a sustainable village, 2. materials and methods, 3.1. changes in the compactness of development, 3.2. preservation of traditional rural spatial arrangements, 3.3. availability of services, 4. discussion, 5. conclusions, author contributions, data availability statement, conflicts of interest.

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Soszyński, D.; Kociuba, P.; Tucki, A. Sustainable Spatial Development of Multifunctional Villages: A Case Study of Eastern Poland. Sustainability 2024 , 16 , 7965. https://doi.org/10.3390/su16187965

Soszyński D, Kociuba P, Tucki A. Sustainable Spatial Development of Multifunctional Villages: A Case Study of Eastern Poland. Sustainability . 2024; 16(18):7965. https://doi.org/10.3390/su16187965

Soszyński, Dawid, Piotr Kociuba, and Andrzej Tucki. 2024. "Sustainable Spatial Development of Multifunctional Villages: A Case Study of Eastern Poland" Sustainability 16, no. 18: 7965. https://doi.org/10.3390/su16187965

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Spatiotemporal landscape pattern changes and their effects on land surface temperature in greenbelt with semi-arid climate: A case study of the Erbil City, Iraq

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• Published: 06 September 2024

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Urban expansion of cities has caused changes in land use and land cover (LULC) in addition to transformations in the spatial characteristics of landscape structure. These alterations have generated heat islands and rise of land surface temperature (LST), which consequently have caused a variety of environmental issues and threated the sustainable development of urban areas. Greenbelts are employed as an urban planning containment policy to regulate urban expansion, safeguard natural open spaces, and serve adaptation and mitigation functions. And they are regarded as a powerful measure for enhancing urban environmental sustainability. Despite the fact that, the relation between landscape structure change and variation of LST has been examined thoroughly in many studies, but there is a limitation concerning this relation in semi-arid climate and in greenbelts as well, with the lacking of comprehensive research combing both aspects. Accordingly, this study investigated the spatiotemporal changes of landscape pattern of LULC and their relationship with variation of LST within an inner greenbelt in the semi-arid Erbil City of northern Iraq. The study utilized remote sensing data to retrieve LST, classified LULC, and calculated landscape metrics for analyzing spatial changes during the study period. The results indicated that both composition and configuration of LULC had an impact on the variation of LST in the study area. The Pearson’s correlation showed the significant effect of Vegetation 1 type (VH), cultivated land (CU), and bare soil (BS) on LST, as increase of LST was related to the decrease of VH and the increases of CU and BS, while, neither Vegetation 2 type (VL) nor built-up (BU) had any effects. Additionally, the spatial distribution of LULC also exhibited significant effects on LST, as LST was strongly correlated with landscape indices for VH, CU, and BS. However, for BU, only aggregation index metric affected LST, while none of VL metrics had a relation. The study provides insights for landscape planners and policymakers to not only develop more green spaces in greenbelt but also optimize the spatial landscape patterns to reduce the influence of LST on the urban environment, and further promote sustainable development and enhance well-being in the cities with semi-arid climate.

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Suzan Ismail & Hamid Maliki

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Conceptualization: Hamid MALIKI, Suzan ISMAIL; Methodology: Hamid MALIKI, Suzan ISMAIL; Formal analysis: Suzan ISMAIL; Writing - original draft preparation: Suzan ISMAIL; Writing - review and editing Hamid MALIKI, Suzan ISMAIL; Funding acquisition: Suzan ISMAIL; Resources: Suzan ISMAIL; Supervision: Hamid MALIKI; Software: Suzan ISMAIL; Visualization: Suzan ISMAIL; Project administration: Hamid MALIKI, Suzan ISMAIL; Data curation: Suzan ISMAIL; Investigation: Suzan ISMAIL; Validation: Suzan ISMAIL. All authors approved the manuscript.

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Ismail, S., Maliki, H. Spatiotemporal landscape pattern changes and their effects on land surface temperature in greenbelt with semi-arid climate: A case study of the Erbil City, Iraq. J. Arid Land (2024). https://doi.org/10.1007/s40333-024-0027-x

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Received : 13 April 2024

Revised : 26 July 2024

Accepted : 13 August 2024

Published : 06 September 2024

DOI : https://doi.org/10.1007/s40333-024-0027-x

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