In this section you will find articles about infants, which developmentalists define as extending from birth to two years.  Many areas are discussed, including social and cognitive development, emotional development, brain development, personality and temperament, as well as individual and cultural variation.

Infant and Toddler Nutrition
Starting solid food is a major milestone in development

infant at breastThere are many milestones in the first year that mark significant changes in the way your child interacts with the world. One of the most radical and elemental of these changes is the introduction of solid food and the transition away from breastmilk (or formula) as the only source of nutrition.

As energy and nutrient requirements change with growth, and as toddlers develop new feeding capabilities, they are introduced to a new variety of foods, which in turn exposes them to new smells, textures, and flavors. Learning to feed oneself is another important milestone related to food during this period. So is the social learning that takes place during mealtime routines and communal eating.

Optimal nutrition in early childhood not only supports physical and cognitive growth and development, but modeling healthy behaviors around food, and exposing your child to a variety of food choices, can help to initiate and reinforce healthy eating habits that will set the direction for future development.

When To Introduce Solid Food

Parents often wonder how and when to begin introducing solid food, and this seems to be an area where research has yet to influence real-world practice. The World Health Organization (WHO) recommends exclusive breastfeeding for 6 months, and continued breastfeeding up to age 2. The American Association of Pediatrics (AAP) recommends introducing solid foods no sooner than 6 months of age.

However, a 2007 report from the CDC showed that while 3 out of every 4 new mothers in the United States initiate breastfeeding, only 33% are exclusively breastfeeding by 3 months. A 2011 study, that received widespread news coverage, showed that formula-fed babies are at higher risk of obesity at age 3. Among those that were formula-fed and started on solid foods before 4 months of age, the risk of obesity at age 3 was even greater. Another study published in Pediatrics showed that starting solid foods before 6 months of age might have effects on weight and health that extend into childhood.

Breast milk helps kids develop their taste for food!

While the health benefits of breastmilk are well known, new research suggests that flavor alsoasian child eating nodles plays a role in the link between breastfeeding and health. Breastmilk transmits most of the flavors from mom’s diet, while formula carries a standardized and unchanging flavor profile. This seems to influence developing food preferences. There is a developmental “flavor window,” which is open roughly between 4 and 7 months.

For example, one study demonstrated that breastfed infants whose mothers ate a concentrated amount of carrots, showed a preference for carrots as toddlers. It has long been known that both amniotic fluid and breastmilk have their own person-specific smell and taste that are influenced very much by mom’s diet. Newer research suggests that there might be real benefit in extending breastfeeding throughout the flavor window to prime toddlers to be more accepting of a varied diet.

Based on the AAP guidelines, infants under one year should be primarily breastfed, with small amounts of pureed whole foods introduced slowly around 6 months of age. By 12 months, an infant’s milk intake should be tapered down from around 24 to 16 ounces a day, to make room for solid foods.

As children are weaned and transition to a diet more similar to that of adults, it is important to keep in mind that the foods they eat must supply all the essential nutrients required to support their important developmental needs. In other words, there really is no room in a child’s diet for foods with low nutritional value. In reality this is true for all of us, but especially so for young children.

How much food do toddlers and young children need?

father feeding toddlerAccording to the AAP, a one-year old needs about 900 calories, 30-40% of which should be from fat. Their diet should also include at least 2 ounces of whole grains, 1.5 ounces of lean protein, 16 ounces of dairy (preferably breastmilk) and 8 ounces of fruit. Two- and three- year olds need 1000-1200 calories a day and an additional ounce of both protein and grains, with about 30% of those calories coming from fat.

By the time they are four and five years old, children need around 1200-1400 calories a day (20-25% from fat), 5 ounces of grains, and 4 ounces of protein. More active children may require more calories. In addition to the macronutrients like fat and protein, all children need to eat micronutrients (i.e., vitamins and minerals) to support organ and immune health.

Fat is especially important for younger children. This is because their brains are building important white-matter tracts that help speed up the way messages are transmitted between brain cells. This white matter, called myelin, is primarily made from fat. Protein and complex carbohydrates are important for physical growth and cognitive development, and micronutrients (vitamins and minerals) support the development of all our major organs, plus the health and function of nerves, blood vessels and the immune system.

The best way to ensure optimal nutrition for your child is to provide a varied diet of whole and unprocessed foods. However, that sometimes feels easier said than done, as young children can be sensitive to unfamiliar smells, textures, and flavors. Also, toddlers are in a developmental stage that involves testing boundaries and asserting individuality, two tendencies that can result in defiance and willful pickiness around food. If you offer only healthy choices and stay calm, your toddler will be fine.

If you have any questions or concerns about your child’s eating, it is important to discuss them with your physician or health care provider.

Written by Emily Owen, Ph.D., BSN

Dr. Owen is a developmental psychologist who also holds a degree in nursing and is a certified postpartum doula. She is a developmental science writer for Insights for Parents. You can read more about her work here or visit her website.

Watch for our upcoming article on how to encourage the development of healthy attitudes and behavior about food. It will appear soon in the Early Childhood section.

Primary Emotions

The very first emotions appear during infancy, mostly from 1 - 7 months or so. They seem to be universal. That is, people all around the world have these emotions and express them in visibly similar ways. We can recognize facial expressions of fear or joy in people from all different cultures and ethnic backgrounds. We call these the “primary emotions.”

Primary emotions don’t need to have social input to be learned or expressed. In fact, infants born blind smile and grimace and produce other facial displays, even though they have never seen someone else smile . . .

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Attachment Part 4: Infants and Beyond

The Long Term Influence of Attachment Patterns

As children grow older the quality of their attachment to their parent influences how much they trust their parents. Parents are an important source of knowledge, advice and information for children and adolescents. Teens and older children are far more likely to rely on and trust parents when they enjoy a secure relationship with them. As children mature, they begin to form attachments with close friends, and, as teens, sometimes to romantic partners. These do not replace . . .

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The Development of Attachment in Infants, part 3

Infant Attachment part 3: Factors That Influence Attachment

Quality of Caregiving

The security of attachment is influenced by the quality of care an infant receives. For the most part:

♥ Secure infants have responsive, attuned caregivers

Attuned parents are sensitive to their child’s signals. During infancy these parents respond, but do not lead or overwhelm. They sensitively withdraw when their infant disengages. Parents who are attuned can view things from their child’s perspective and adjust responses to their child’s needs. In . . .

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The Development of Attachment in Infants, part 2

Attachment in Infants Part 2: Studying Attachment: How the Attachment Styles were Identified

In 1978 Mary Ainsworth, who had been a student of Bowlby’s, designed a playroom in a laboratory setting that can be used to evaluate the quality of children’s attachments to their mother or other main caregiver. The procedure is known as “the strange situation room.” Strange in the sense of unfamiliar. It is one of the great landmark studies in developmental psychology and has led to countless replications in . . .

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The Development of Attachment in Infants, part 1


happy curious child held by fatherAttachment refers to the special feeling of connection older infants come to have for a particular person who cares for them. The deep sense of love and commitment that parents feel for their infant is called a “bond.”

You may want to read our introductory article on attachment and how developmental scientists have come to understand it, which you will find in the section on General Development.



The Key Idea: ♥  The main insight about attachment is that the person a child is attached to becomes a “secure base,” from which an infant or child can venture into the world — or into an unfamiliar space — and begin to explore and interact with the people and things that are there. When a child is comfortably attached, she has a trusting sense that she can return to the person if she needs support, enjoys sharing things she discovers, and likes to check in from time-to-time. The secure base allows the child to become independent, while still feeling safe.

This sense of trusting support carries into childhood, adolescence and adulthood. It actually endures a lifetime.

The quality of attachment varies somewhat among children. The majority of children in the United States (about 60 – 65%) enjoy a secure attachment with at least one person. The remainder have somewhat less secure attachments. These different styes are explained in our second article on attachment.

The Development of Attachment

Attachment develops gradually over the course of the first year, following a fairly predictable course. The table below shows you what most parents experience and developmentalists observe.

Typical Sequence in Becoming Attached

Phase Age Description
Pre-Attachment 0 – 2 months Comfortable with most people, responds indiscriminately in social situations
Early development of attachment 2 – 7 months  

Recognizes familiar people, greets & engages with them.

Attachment 7 – 24 months  

Protests when separated, cautious or wary of strangers, intentional social interactions and communication

Partnership 24 months  

Child begins to understand needs of others and relationships becomes more reciprocal


Infant Attachment, part 2, describes the 4 different attachment styles children display.

Is Baby Talk Okay??

Baby Talking isn’t just okay, it’s perfect. For babies. A lot of people worry that baby talking to an infant or young child is dumbing things down and should be avoided. Yet if you watch your infant, you’ll notice she responds to the high pitched sounds, exaggerated intonation and simplified words that are characteristic features of baby talk.
Infants are born well equipped for social interaction and they are particularly well prepared for vocal interactions. Hearing is very well developed . . .

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Newborns Can Imitate You
Did you know newborns can the imitate facial expressions they see??
(And why that’s interesting….)

In 1979 two developmental scientists published research reporting that two-week-old infants can imitate facial gestures such as sticking out their tongues, making a big open O-shape with their mouths and raising their eyebrows. It was an amazing report. Within three years it was replicated and discovered that babies can in fact imitate within minutes of birth, as soon as anyone (parent or scientist) presents a facial display for them to copy.

This research took the developmental psychology and psycholinguistic world by storm. It implied that newborns can notice, remember, cognitively match a set of facial features from another to their own faces and deliberately match the display. And they did all this without ever observing themselves in a mirror nor having ever before seen another human face. It suggested neonates have a great deal of cognitive ability and intentionality. That’s what I taught my students during the 1990s and what I told parents in discussing ways to enjoy newborns.

The behavior is very real, but our explanation for it was probably wrong. We now largely attribute infant imitation to mirror neurons. Sensory and motor areas of the brain have neurons that are responsible, in various ways, for perception and action. In addition, these areas have some neurons called “mirror neurons,” something first discovered and described around the turn of the millennium. Mirror neurons fire when a person perceives an action or behavior performed by someone else. That shiver you feel when you see someone cut himself is caused in part by mirror neurons. The emotional pain you feel when someone is sad may also involve mirror neurons, in companion with information from your own personal experiences with sadness.

Back to newborns. The remarkable capacity for imitation probably isn’t some high level cognitive process, but rather a response triggered by the firing of mirror neurons. Yet, it is still incredibly interesting and important.

Why it matters

Facial imitation in babies serves several adaptive functions. That is, it supports development in a number of important ways. Observing others making facial displays captivates babies and draws them into social interaction. It also helps nurture the bond parents feel toward their infant. You may or may not have actually noticed your baby responding to you in this way, but you will have probably felt a kind of synchrony between yourself and your newborn when you gaze at one another and exchange facial gestures. So the newborn’s amazing capacity to imitate facial displays draws them into the social world and also strengthens a parent’s commitment to tend to them.

Some researchers believe mirror neurons contribute to the development of empathy. When we experience a mirror response of what others experience, it lays a foundation for recognizing and responding to the needs and concerns of others. Thus, mirror responses and more sophisticated cognitive and social responses may combine to create feelings of empathy. Mirror neurons, by the way, are not unique to humans, but are found in the cortex of most primates and many other animals, especially those with advanced social behaviors, such as elephants.

How to enjoy imitation games with your newborn

Choose a time when your infant is in an active awake state (awake, alert and comfortable, but not occupied with vigorous motor activity)

Bring your face within your infant’s focal range, about 12 inches in front of his face. (You may enjoy holding your infant or prefer to let your baby rest in a little infant seat.)

Look into your baby’s eyes and slowly stick out your tongue, leaving it out for little while so your baby can take it in. Give your baby a chance to gather himself and see if he sticks out his own tongue. If he doesn’t, try sticking out your tongue again. Keep things gentle and slow. It takes a while for babies to process information and then coordinate their own behavior. You may enjoy trying other facial displays — the open O mouth or raising your eyebrows in an exaggerated way often elicit imitations. Experiment.

Remember, babies respond in their own time. If your newborn doesn’t imitate you, try again another day. And enjoy making sounds to your baby and holding up objects for her to look at and track as you slowly move them near her face. There are many ways to enjoy social interactions with newborns.

Here’s a link to a video that shows a 10-minute-old infant imitating his father.

What is stranger anxiety?

What it is like
Babies become very attached to their most important caregiver, usually their mother, and they feel less comfortable, or even quite upset, with people who are unfamiliar. You won’t see real “stranger anxiety” right away; it comes when your baby starts building a trusting connection with you and has gained some understanding about the world.

Experienced parents and developmental scientists observe a series of phases as an infant becomes attached to an important person. During the first 7 months or so, infants . . .

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Tuning Into Your Newborn
Newborns:  Different ways of being awake

Have you noticed that your very young infant sometimes seems to engage with you in a sort of magical bubble that contains just the two of you and other times seems less interested in gazing at your face and being with you?  You may have tuned in and instinctively responded to these varying patterns.  Here’s why they happen.

Newborns actually have six states:  three sleep and three awake.


Sleeping babyDEEP SLEEP, in which your infant breathes deeply and rhythmically, occasionally jerking her body or making sucking movements with mouth.  (This isn’t a good time to awaken her to feed or go somewhere, as she’ll wake only briefly and needs to sleep.)

REM SLEEP, this dream sleep is usually the biggest part of the day for a newborn.  You’ll see him move, suck, whimper and perhaps even cry briefly.  His brain is exploring and integrating all the stimulating sensory experiences he’s been having.  (If he cries in this state, you needn’t immediately reach to comfort him.  Instead pause a moment to see if he resettles, it may be part of his dream sleep.) 

DROWSY is an in between state, with irregular breathing. Your baby’s eyes may not focus and may even be cross-eyed.  She will either return to sleep or rouse.  (You have a choice here, you can pick up your baby and draw her into the world or watch and see if she returns to sleep.)


CRYING is how your tiny infant lets you know he needs your help.  Sometimes there is a clear need – to be fed, changed or comforted.  Other times, infants seem to cry as part of getting themselves organized and integrated into the world.  (You will quickly build some intuitions about your infant, responding knowingly to many needs.  Other times, your presence and touch may be what you can best offer.)

ACTIVE AWAKE is a time when your infant is using her body, working muscles and eventually moving her head, arms and legs.  It’s triggered in part by the nerves in various parts of the body becoming myelinated and better connecting.  If your baby is happy in this state, she’s probably discovering her body, exercising it and strengthening it.  (She may enjoy your cycling her legs or moving her arms or she may not, you can explore).  If your infant becomes fussy in this state it is a signal that she needs feeding or comforting.

QUIET ALERT is the magical time, when your infant is attentive and interested in you and the world.  He is calm and still, observing you and his surroundings, listening to you speak, enjoying things you share with him.  These minutes are the times to play games, hold up interesting objects for him to slowly track as you move them before his face; laugh, smile, talk gently to him and hold his gaze with yours.  You are helping him open the door to his social world and learn about his physical world.

Newborn baby

Responding to these natural states opens the way to being an attuned parent.