Welcome to Your Child's Brain: How the Mind Grows From Conception to College (27 page)

Banning electronic media throughout childhood is probably unnecessary and certainly unrealistic. Even if you could enforce such a ban successfully, cutting your child off from his peers’ favored communication methods would place him at a severe social disadvantage, and lack of experience with computers might lead to professional difficulties later on.

Even so, there are strategies you can use to reduce the negative impacts. Providing time for other activities by limiting screen time is likely to be beneficial for development. There is no doubt that childhood experiences influence brain development, so it’s worth making sure that the important ones are available to your child. Children need exercise (see
chapter 15
), they need face-to-face interaction (see
chapter 20
), and they need to spend time outdoors (see
chapter 10
). In that light, your mom’s suggestion to “Go outside and play” is backed not only by common sense but by modern brain research. Dandelions need to see the sun every so often.

PART FIVE
YOUR CHILD AS AN INDIVIDUAL

NICE TO MEET YOU: TEMPERAMENT

EMOTIONS IN THE DRIVER’S SEAT

EMPATHY AND THEORY OF MIND

PLAYING NICELY WITH OTHERS

Chapter 17
NICE TO MEET YOU: TEMPERAMENT

AGES: BIRTH TO TWENTIES

Many people start reading parenting advice books before their baby is born—not to learn how to change a diaper or breast-feed, but to find out how to make their baby intelligent or sociable. If it doesn’t seem a little odd to be trying to figure out how to build a good relationship with someone you haven’t met yet, perhaps that’s because your culture assumes that babies are blank slates who can grow up to become any kind of person, no matter what their individual characteristics may be. You can see this kind of reasoning across the political spectrum: from liberal parents who are horrified to find their son playing war with sticks after being forbidden to have toy guns to conservative parents who believe that therapy can turn their gay son into a straight man.

As we have said, most children flourish to a similar extent regardless of circumstances, as long as conditions are “good enough.” This is true of personality, where, as with so many other brain functions, the vast majority of children are dandelions. Indeed, there are limits on how much parents can influence their children’s personalities. It may sometimes seem otherwise, but this is good news: you do not bear the sole responsibility for your children’s success and happiness in the world.

Although your child’s personality is indeed shaped in part by environmental influences, it’s worth remembering that not all of them come from you. This may be easier to understand if you keep in mind that the nuclear family is a recent invention in the history of our species. During most of our evolution, children were raised by a community and were often cared for by older children as well as adults. For many cultures, the situation is still the same today. Wherever you live, your child is likely to spend much of his time with others: in school, at play, and with siblings, friends, teachers, and other people. Taken together, these factors are usually sufficient to lead to a good outcome (though see
chapter 30
for what happens when environmental conditions are not good enough).

First-time parents sometimes manage to hold on to the blank-slate illusion for a while, but anyone who’s had more than one child has been clued in that this idea is wrong. Even at birth, babies differ from each other in important
ways.
Temperament
is a psychological term for the individual differences in infants that form the basis for adult personality. Temperamental characteristics include activity level, attentional persistence, and how easily the child feels fear, anger, frustration, or happiness. Like most early differences between individuals, temperamental characteristics do not absolutely determine outcome, but they do influence the relative likelihood of various adult personality traits and the range of possibilities available to a particular child. Perhaps more important for parents, they also influence your child’s response to different parenting styles—and vulnerability to various developmental problems.

Even at birth, babies differ from each other in important ways.

One of the best-studied aspects of temperament is whether babies react calmly or with distress to unexpected events. Nearly one in five infants are
high-reactive babies
, who kick and cry when exposed to something new or strange (but not especially scary), like a dangling mobile over the crib. As they grow into toddlers, such children tend to be what the scientific literature calls
behaviorally inhibited
—and what the rest of us would call shy or reserved. When high-reactive babies are followed into early adulthood, they are likely to be introverted and are at higher risk than calm babies of growing up to be worry-prone adults, even if they don’t have a formally diagnosed anxiety disorder.

Various experiences can nudge a high-reactive child’s developmental path in a less-anxious direction. For example, infants who are unusually irritable at fifteen days of age are more likely than other babies to become insecurely attached to their mothers at one year (see
chapter 20
), but this outcome is much less likely if the mothers are trained to soothe restless babies effectively. In general, about half of all high-reactive babies raised in the U.S. become fearful children sometime before age seven. The good news is that only a third of these babies become anxious adults. The others tend to become detail-oriented, well-prepared, and thus often successful people. Among other things, they make good scientists (Sandra was a high-reactive baby), though it’s rare for them to be the life of the party or to pursue careers as politicians or salespeople.

Among adults without anxiety problems, those who started life as high-reactive babies are more vigilant than people who were calm as infants. In one
laboratory test, vigilant adults find it difficult to disengage their attention from threatening faces on a computer screen. Most people become tense when watching a blue screen that signals that they might be hit with an unpleasant air puff, but only adults who were high-reactive babies stay tense in the presence of the green screen that signifies safety. These laboratory reactions don’t matter much in everyday life, but there is a broader, important point: there are real biological differences underlying high-reactive temperament, and these differences persist into adulthood.

Among children or adults, personality doesn’t require that you must act a certain way all the time. Instead it sets thresholds that make you more or less likely than average to behave in certain ways in a given context. For instance, most shy people don’t feel inhibited in front of family members, and even an outgoing person might feel shy while speaking to an audience of thousands. Still, personality has an important influence on life outcomes. Indeed, personality traits are as effective as IQ (see
chapter 22
) or socioeconomic status (see
chapter 30
) at predicting the probabilities of various life events, such as divorce or work success.

The most widely accepted model of adult personality contains five factors: openness to experience, conscientiousness, extroversion, agreeableness, and neuroticism. These factors vary among individuals across many cultures, from Malaysia to Estonia. The stability of personality traits increases with age, being relatively stable after thirty years of age, especially from fifty to seventy. All five factors show strong heritability, meaning that people who are more closely related are more likely to share personality traits. For this reason, you are likely to have some personality characteristics in common with your biological parents, even if you are adopted and have never met them.

On the other hand, even identical twins have noticeably different personalities, so some life events must help to determine how personality matures. It has proven surprisingly difficult for researchers to determine which aspects of experience influence how temperament unfolds into adult personality. Behavioral genetics studies consistently find that the environmental influences shared among children in the same family have little or no effect on their adult personalities. Indeed, identical twins reared together are no more similar in their personalities than those reared apart. As you may recall from
chapter 4
, though, these studies sweep up gene-environment interactions into the “genetic” category, which creates some misperceptions. This is important when it comes to personality, where gene-environment interactions have important effects.

DID YOU KNOW? WHY YOU’RE TURNING INTO YOUR MOTHER

On average, when it comes to personality, children turn out much like their biological parents. One reason is that your genes affect your life experiences. Babies’ temperaments influence how other people interact with them—a lot. People tend to talk about kids who grow up in the same family as if they share the same environment, but there are many important differences, including the ways that each child relates to parents, siblings, and eventually peers.

From the moment a baby is born, parents react to his or her individual characteristics. Parents would find it impossible (and senseless) to speak to a willful toddler in the same way that they do to an amiable one. Similarly, a child who is sociable will get more practice at speaking and listening than one who’s most interested in playing with his train set in another room. These are among the many reasons why it makes no sense to talk about heredity and environment as separable factors in development.

As children grow, their innate differences in temperament and the resulting individual differences in experience often reinforce each other’s effects. Older children can control their environments to a greater extent than younger children, for example, by choosing to take gymnastics lessons instead of reading books in their free time. Perhaps for this reason, individual differences tend to become more pronounced later in life—and most obvious of all in adults. Genetically related people share more personality traits in adulthood than they do in childhood. People’s increasing ability to choose environments that are well matched to their individual tendencies could explain why.

Although parents don’t like to admit it, individual children within the same family are raised in different ways, often linked to their temperaments (see
Did you know? Why you’re turning into your mother
). In addition, the same environment may have different effects on children with different genes. As researchers have started to look for examples of how gene-environment interactions influence
personality development, they have found a variety of effects. Temperamentally anxious children develop more empathy in response to gentle child-rearing techniques than do bolder children (see
Practical tip: Promoting conscience
). Children with a specific receptor that makes them prone to hyperactivity and impulsivity (including ADHD; see
chapter 28
) are more sensitive to parenting style than other children. Eventually, parents may be able to personalize their interaction styles to produce a desired outcome based on the characteristics of an individual child, but researchers have a lot of work to do before that dream becomes reality.