Welcome to Your Child's Brain: How the Mind Grows From Conception to College (3 page)

Between us, we have over forty years of experience as neuroscientists. Sandra started in the laboratory doing research on brain development and
plasticity
*
and went on to edit one of the leading journals in neuroscience. She has read thousands of papers, many of them reporting pioneering discoveries. Her critical eye comes from having a view of the field that is both broad and deep. She knows when a result is sound and when it is fishy.

Sam is a professor and researcher at Princeton University. He has been publishing original research and teaching students for over twenty years. His own
research concerns how the brain processes information and learns—and how this process can go wrong in early life.

Sam is also a dad. Before his daughter came along, he used to talk about what we called
cocktail party neuroscience
. Life changed for him, so now it’s
preschool potluck neuroscience
. At these parties, parents and teachers ask lots of fun questions, but sometimes he’s noticed a touch of anxiety as well.

Your questions sent us to the library. Together we scoured the technical literature, studying many hundreds of papers in neuroscience, psychology, medicine, and epidemiology. We synthesized this vast literature into our best interpretation of what is known about children’s brains. This book is the result of all that research. In it, we explain the science, debunk myths, and include practical tips for you as parents.

Here’s our first instruction:
take a deep breath and relax
. Really. The things
you’re worrying about are much smaller factors in your child’s well-being than you might imagine. Many modern parents believe that children’s personality and adult behavior are shaped mainly by parenting—but research paints a very different picture.

Here’s our first instruction: take a deep breath and relax. Really
.

There is a simple way to summarize much of the research on the neuroscience of child development: children grow like dandelions. In Sweden, the term
maskrosbarn
(
dandelion child
) is used to describe children who seem to flourish regardless of their circumstances. Psychological studies suggest that such children are relatively common (at least when raised by “good enough” parents who do not abuse or neglect them). From an evolutionary perspective, this makes sense; children who can make do with whatever time and attention their parents can spare are more likely to survive and pass along their
genes
under tough conditions. For many brain functions, from temperament to language to intelligence, the vast majority of children are dandelions.

The developing brain has been shaped by thousands of generations of evolution to become the most sophisticated information-processing machine on Earth. And, even more amazingly, it builds itself. For instance, you do not need to teach your children to notice—and eventually produce—human speech. Your baby son or daughter knows, very early on, that the noises you make have more meaning than other sounds. So even if you never give your children a speech lesson, they are highly unlikely to start imitating the air conditioner or the family cat. At least not convincingly.

Children are not passive recipients of parenting or schooling, but active participants in every aspect of their own development. From birth, their brains are prepared to seek out and make use of experiences that suit their individual needs and preferences. For this reason, brain development requires no special equipment or training, and most children find a way to grow in whatever conditions the world has to offer them.

If children are so adaptable and smart, why can’t they start using their brains for high-powered activities right away? In large part it’s because the development process tunes each individual’s brain to the characteristics of a particular environment.
This is one reason that people can live successfully all over the world. Genes provide the blueprints for your child’s individuality, but the plans are certain to be modified during construction depending on local conditions—not only your actions as parents, but also your child’s culture, neighborhood, teachers, and peers. This matching process is automatic, with some support from you along the way. All this leads us to the major theme of this book:
your child’s brain raises itself
.

In a few circumstances, extra help is necessary. Things can go wrong if the genetic program has a flaw or if environmental conditions are very difficult, as happens in poverty or war. Modern life has also created some new challenges. Brain development can get into trouble when our modified environment fails to play nicely with our ancient genetic heritage. For these cases, we tell you how to give your child that extra boost.

We organized the book around seven scientific principles that will help you understand how your child’s brain grows and changes along the path to adulthood.

• Part 1, Meet Your Child’s Brain
. This section is an introduction to your child’s brain and how it works. In particular, we talk about how innate predispositions for interacting with the outside world initiate a two-way conversation between genes and environment that shapes neural development throughout childhood.

• Part 2, Growing Through a Stage
. The brain goes through periods when it builds upon earlier foundations and is exceptionally sensitive to certain types of information. This section describes the experiences that your child’s brain uses to shape the development of sleeping, walking, and talking.

• Part 3, Start Making Sense
. Much of neural development relies on experiences that are easily available to almost any child. As parents, you get a free ride on this process; simply sit back and watch your child’s senses tune themselves to the world.

• Part 4, The Serious Business of Play
. One of the major ways that children adapt to their circumstances is through play. From preschool through adolescence,
play is practice for adult life and helps to develop some of the brain’s most important functions.

• Part 5, Your Child as an Individual
. Distinctive features of the genetic program make your baby a unique person from the start. Here we explain how your child’s individual emotional and social characteristics grow and respond to the surrounding world.

• Part 6, Your Child’s Brain at School
. Most of the evolutionary history of our species happened before there were books, violins, or calculus—not to mention Facebook. We tell you how the flexibility of your child’s brain allows her to handle abstract concepts that our ancestors never imagined.

• Part 7, Bumps in the Road
. All environments present challenges to the developing brain. Most children can get what they need to grow, like dandelions, but a few are more delicate flowers needing extra care or attention. We explore what you can do to help your child if anything goes wrong.

Feel free to dip in anywhere that interests you. Headings indicate the age range that is the focus of each chapter, so that you can easily find out whether we have something to say about your child’s brain, however old he or she is right now. As you can see, we’ve got a lot of ground to cover, so let’s get started.

PART ONE
MEET YOUR CHILD’S BRAIN

THE FIVE HIDDEN TALENTS OF YOUR
BABY’S BRAIN

IN THE BEGINNING: PRENATAL DEVELOPMENT

BABY, YOU WERE BORN TO LEARN

BEYOND NATURE VERSUS NURTURE

Chapter 1
THE FIVE HIDDEN TALENTS OF YOUR BABY’S BRAIN

AGES: BIRTH TO ONE YEAR

Your baby is smarter than he or she lets on. For generations, the slow development of
motor
systems led psychologists to believe that babies had very simple mental lives. In a baby who has not worked out how to walk or talk, mental capacities cannot be measured by approaches used to test grown-ups. But in the past few decades, scientists have figured out better ways of getting information from infants. With these new tools, researchers have shown that babies’ minds are very complex right out of the box—as many parents suspected all along.

All brains, young and old, have certain broad talents that help their owners to navigate life successfully. If you look closely, you can already see many of these talents in your infant. Although babies lack knowledge, they are born with certain tendencies that influence how they organize incoming information and respond to it. They are predisposed to seek out experiences that will help adapt their growing brains to their particular environment. Or, to put it more simply, your child’s brain naturally knows how to get what it needs from the world. For this reason, most brain development requires only a “good enough” environment (more on that later), which includes a reasonably competent (though not perfect) caretaker.

What do babies know and when do they know it? They can’t tell us in words, but researchers can still ask babies questions and get sophisticated answers about their
cognitive
abilities. A few simple, nonverbal ways of looking into the minds of infants and even newborns have revolutionized developmental psychologists’ ability to tell what young babies think and feel.

Your infant isn’t good at controlling most of her body, but she can suck on a nipple immediately at birth. Not long after that, she can turn her head and eyes to look at an interesting object or event. These two abilities can be used to find out what catches her attention. For example, if your infant likes an event that happened while she was sucking and wants it to happen again, she will suck more vigorously. Your newborn will suck harder when she hears a recording of her mother speaking, but less so when she hears another woman. This is how we know that, from birth, infants recognize Mom’s voice.

Like adults, babies get bored. After your baby has looked at something for a while, he will turn away and look at something more interesting. Researchers
can observe how long a baby looks at a particular scene. If the scene contains something surprising to the baby, he will look longer.

This response allows us to find out whether a baby can tell the difference between two things. For example, if you show your baby a series of pictures of cats, the appearance of a dog will attract a long look. This means that babies can distinguish cats from dogs—a feat that is extremely difficult to program into a computer.

Simple tools like these enabled researchers to identify five brain talents that infants already have well before their first birthday.

The first talent: babies can detect how common or rare particular events are.
For example, a first step in learning a language is figuring out which syllables go together to form a word. Yet when speaking, people tend not to pause between words. One way to learn words is to determine which syllables are likely to occur together. For example, when your baby hears the words
the baby
being spoken, how can she tell that it’s the English word
the
followed by
baby
, and not the made-up word
theba
and then
by
? One clue is that
baby
is a far more common pairing of sounds than
theba
.

A well-designed experiment showed that in general, babies really do think this way. Researchers generated four nonsense words, such as
bidaku
, each composed of three syllables. They then presented these nonsense words to eight-month-old babies in varying order, without pauses between the words. Once the babies were familiar with these new words, the researchers then presented either one of the nonsense words or a new one composed from the original syllables (like
kudabi
). They let the babies control how long the words were played by looking in the direction of the speaker. The researchers found that babies listened significantly longer to the new words, even though the component syllables were the same. Since the babies had already heard all the syllables individually, the researchers concluded that they must have become familiar with the original groupings. This ability to detect the probability of events, shared by many animals, is a key component of learning. It provides the basis for answering important questions like “Where am I most likely to find food right now?”

The second talent: babies use coincidences to draw conclusions about cause and effect.
After language develops, two-and-a-half-year-old children can make explicit causal statements like “He went to the refrigerator because he was hungry.” But well before this, babies appear to be able to detect such relationships.

In one experiment, a mobile was hung over the crib of three-month-old babies and attached to one leg by a ribbon. When a baby kicked, the mobile would move. The babies were fascinated by this new toy. They smiled more and looked at the mobile more than they did when a similar mobile was out of their control. After just a few minutes of training, they kicked more. Three days later, they still kicked when they saw the first mobile (but not a different one), even when the ribbon was no longer tied to their legs. Since the kicking was a specific response intended to get the mobile to move, these babies seem to be learning an elementary form of cause and effect. Using events that occur together to determine possible underlying causes is a key part of our ability to learn how the world works.