Welcome to Your Child's Brain: How the Mind Grows From Conception to College (31 page)

Mirror neurons are just one example of how single neurons can represent surprisingly abstract concepts. The inferior temporal cortex contains neurons that fire selectively in response to faces, body parts, other objects, the memory of recent objects, and even a person’s identity. Researchers recorded a single human neuron that responds both to an image of the actress Halle Berry and to the letters H - A - L - L - E - B - E - R - R - Y. Recognizing a celebrity may not have the same social importance as learning empathy for other people, but the abilities of the neurons are just as amazing.

Children at this age can remember what they were pretending before and have conversations with themselves in the present. Strangely, though, they cannot remember their previous mental states. For instance, if you give a hungry child his lunch, by the time he is done he is unable to recall that before eating, he was hungry. Likewise, if you play a game with a pencil box in which you surprise the child with crayons instead of pencils, once he has seen the crayons he cannot recall once thinking that there were pencils in the box. Adults also can have difficulty remembering their past mental states, such as whether they liked a roller coaster while they were on it. Perhaps you know one or two people who are like this.

Thinking about one’s past or future self and thinking about other people are closely related. Both capacities involve self-projection—the ability to think about mental states that are not currently your own and to shift perspectives in general. These capacities require the most frontal parts of the brain, which are the latest to develop.

Frontal brain development has additional profound consequences. Children begin to see events from multiple points of view. Also, we learn to understand ourselves at least in part by observing others and their reactions to us. Finally, the ability to attribute feelings and intentions to others is an essential component of mature religious beliefs, which depend on faith in unseen motives. Although fibbing is socially and often practically undesirable, it also represents the opening of new vistas for your child’s mind.

Chapter 20
PLAYING NICELY WITH OTHERS

AGES: BIRTH TO EARLY TWENTIES

Those moments when you feel in sync with your baby, as you trade gestures, facial expressions, words, or just silly noises back and forth, are crucial for early brain development. To you, it’s a fun game of peekaboo. To your baby, it’s an education in self-control, as well as his first experience of relationships.

A sensitive adult can regulate the baby’s arousal level, which young infants can’t do for themselves, by responding to cues (such as turning toward the partner) that indicate when the baby wants more interaction, and to other cues that indicate the interaction has reached its best intensity (smiling) or that the baby is overstimulated (looking away). Even sensitive parents frequently misinterpret their baby’s cues, so that the baby gets a mixed experience of synchrony and missed connections. This seems to be optimal for development.

Babies reach out for this type of interaction thousands of times a day. Young babies become quite upset if their partner briefly stops responding by freezing in place. When this happens, the baby’s heart rate and stress hormone levels both increase. A lack of response is more upsetting to infants than physical separation from the mother or having her turn away to talk to someone else. Even after the partner starts responding again, babies are fussier and less responsive to interaction for a while. After six months, they slowly become better at coping with unreliable responses from their partners and more able to regulate their own arousal.

Problems affecting either parent or infant can interfere with the development of synchronous behavior. Depressed mothers respond more slowly to their babies, are less sensitive to their cues, and show less affection than nondepressed mothers. Their babies are less responsive to faces and voices and show less distress when their partner stops responding to them than the babies of nondepressed mothers. Premature babies’ brains are not mature enough to support normal synchronous interactions, so they are more irritable, signal less clearly, and have more trouble tolerating mismatched interactions. These deficits may be important because better synchrony in infancy predicts more secure
attachment
at one year of age, better self-control at two through six, and more empathy at thirteen.

Attachment is just what it sounds like: a strong and persistent desire to be close to a familiar caregiver, especially when the child is stressed or upset. Infants do not attach to their parents until about six months of age. The delay may seem curious, since parents begin to form attachments much earlier, within a few weeks after birth. But it makes sense from an evolutionary perspective: babies are safer if they are around a protective adult. Young babies pretty much stay where
you put them, so at first it’s more important for the parent to attach. Attachment on the part of the baby serves a protective function only after he can move on his own. Before this age, it appears that the frontal cortex is not yet mature enough to allow the baby to form attachments.

Most babies form attachments to more than one person, though the strongest attachment is usually to the mother. Synchronous interactions contribute to the development of attachments. All babies with normal brains and consistent care-givers form attachments, but the quality of that attachment varies quite a bit. Babies who are securely attached (over half of the population) use their mother as a base for exploration, periodically keep in touch with her as they play, are mildly distressed when she leaves, and are comforted when she returns. Babies with the insecure-ambivalent pattern (under a quarter of the population) stay close to their mother when she is present, are extremely distressed when she leaves, and are alternately clingy and angry when she returns. Babies with the insecure-avoidant pattern (about a fifth of the population) show little apparent distress when the mother leaves and refuse to engage with her when she returns. A rare fourth category, disorganized attachment, is characterized by inconsistent behavior and occurs mainly in babies who have been abused or neglected. Babies may show different attachment styles with different caregivers, but by age five children typically use a single dominant style, which is moderately stable for the rest of their childhood.

By nine months, as babies develop the ability to direct their attention, they become better at initiating synchronous interactions, and they start to experience stranger anxiety, becoming uncomfortable around unfamiliar people. Babies also begin to draw their partner’s attention to objects in several ways: by smiling at the object and then smiling at the person, or by pointing at the object, or by looking alternately at the object and the person. This behavior is more common among infants who respond, when their mother stops interacting, by smiling and making other attempts to engage her socially. Initiating joint attention to an object is one of the earliest indications of social skills, and babies who do a lot of it at nine or ten months are more likely to be rated as socially competent at thirty months.

The outcome of these early social interactions cannot be pinned on either inborn tendencies or parenting style alone. Because social interactions are reciprocal, your baby influences your behavior as much as you influence hers, making it difficult for researchers to sort out the causes of particular interaction patterns. Babies who respond positively to care are likely to receive more attention than
babies who are less happy or are difficult to comfort, probably because their parents find taking care of happy babies more rewarding. For this reason, many parent-infant interactions are self-reinforcing, either positively or negatively. For instance, infants who cry more at six months end up with mothers who respond less at twelve months, but mothers who respond more to their infants at six months end up with infants who cry less at twelve months.

Because social interactions are reciprocal, your baby influences your behavior as much as you influence hers.

We know that synchronous interactions are important to attachment formation because interventions to improve maternal sensitivity increase the probability of secure attachment. Several other factors also contribute importantly to attachment formation, including physical contact, socioeconomic status (see
chapter 30
), and temperament. For example, in a study of economically disadvantaged mothers, babies were more likely to form secure attachments if the mothers used a harness to strap the baby to their bodies than if they used a car seat to hold the infant.

Notably, for most children, the evidence shows that going to day care does not interfere with secure attachment. A longitudinal study in Sweden found only positive effects of day care, though a similar U.S. study found that children with insensitive mothers were more likely to form insecure attachments if they also went to day care before one year of age.

Several long-term studies found that secure attachment in early childhood predicts social competence and better social outcomes in later childhood, particularly in children with a shy or inhibited temperament. For example, attachment security predicts self-control much more strongly in children with a short version of the 5-HTT serotonin receptor (see
chapter 26
) than in children with a long version. The effects of attachment security on later life are small to moderate, so other factors contribute importantly to socialization as well.

Social competence is built on a foundation of basic skills, including self-control (see
chapter 13
), emotional maturity (see
chapter 18
), and theory of mind (see
chapter 19
). All four abilities develop along a similar time course and tend to track together within individuals as well, though with some variability. The similarities probably occur because these abilities are limited by maturation of some of the same brain regions, particularly the anterior cingulate and prefrontal cortex, the latest-developing part of the brain. Social cognition also involves many other regions of the cortex, including the posterior superior temporal sulcus, the temporoparietal junction (the area where the temporal and parietal lobes meet), and the anterior insula, as well as the amygdala.

DID YOU KNOW? STEREOTYPING AND SOCIALIZATION

The way that the brain produces a sense of group membership has a dark side. Social groups are defined not only by their members but also by the people who are outside the group. Especially in situations where groups are competitive, your brain easily attributes negative characteristics to the opposition, the way that Duke basketball fans have a tendency to denigrate the University of North Carolina. This hostility isn’t necessarily restricted to the players, or the basketball program, and may generalize to denunciation of the entire university.

As we discussed in
chapter 1
, your child’s brain is naturally inclined to put things and people into categories. Young children tend to use the most visible characteristic to sort out categories. For this reason, young children are sensitive to superficial group differences like race, whether or not they are explicitly pointed out. This sensitivity starts to emerge during the preschool years, when children begin to socialize in groups. A difference as meaningless as giving children shirts of different colors can create a feeling of membership that causes them to like children within their own group better than children of the other group. Unless parents actively teach children not to attribute characteristics to people by race, they are likely to socialize preferentially with others of their own race. This pattern persists throughout the school years even among children who go to mixed-race schools and day-care facilities.