Even the youngest children know, experience and learn far more than scientists ever thought possible.

Key Concepts

■          Babies' and young children's cognitive abilities far surpass those that psychologists long attributed to them. They can, for instance, imagine another person's experiences and grasp cause and effect.

■          Children learn about the world much as scientists do—in effect, conducting experi­ments, analyzing statistics and forming theories to ac­count for their observations.

■          The long helplessness of babies may be a . . . trade-off, a necessary consequence of having brains wired for prodigious feats of learning and creativity.  —The Editors

Thirty years ago most psychologists, philosophers and psychiatrists thought that babies and young children were ir­rational, egocentric and amoral. They believed children were locked in the concrete here and now—unable to understand cause and effect, imagine the experiences of oth­er people, or appreciate the difference between reality and fantasy. People still often think of children as defective adults.

But in the past three decades scientists have discovered that even the youngest children know more than we would ever have thought possible. Moreover, studies suggest that children learn about the world in much the same way that sci­entists do—by conducting experiments, analyz­ing statistics, and forming intuitive theories of the physical, biological and psychological realms. Since about 2000, researchers have started to understand the underlying computational, evo­lutionary and neurological mechanisms that un­derpin these remarkable early abilities. These revolutionary findings not only change our ideas about babies, they give us a fresh perspective on human nature itself.

Physics for Babies

Why were we so wrong about babies for so long? If you look cursorily at children who are four years old and younger (the age range I will discuss in this article), you might indeed con­clude that not much is going on. Babies, after all, cannot talk. And even preschoolers are not good at reporting what they think. Ask your average three-year-old an open-ended question, and you are likely to get a beautiful but incomprehensible stream-of-consciousness monologue. Earlier researchers, such as the pioneering Swiss psy­chologist Jean Piaget, concluded that children's thought itself was irrational and illogical, ego­centric and "precausal"—with no concept of cause and effect.

The new science that began in the late 1970s depends on techniques that look at what babies and young children do instead of just what they say. Babies look longer at novel or unexpected events than at more predictable ones, and exper­imenters can use this behavior to figure out what babies expect to happen. The strongest results, however, come from studies that observe actions as well: Which objects do babies reach for or crawl to? How do babies and young children im­itate the actions of people around them?

Although very young children have a hard time telling us what they think, we can use lan­guage in more subtle ways to tease out what they know. For example, Henry Wellman of the Uni­versity of Michigan at Ann Arbor has analyzed recordings of children's spontaneous conversa­tions for clues to their thinking. We can give children very focused questions—for instance, ask­ing them to choose between just two alternatives, rather than asking an open-ended question.

In the mid-1980s and through the 1990s, sci­entists using these techniques discovered that babies already know a great deal about the world around them. That knowledge goes well beyond concrete, here-and-now sensations. Researchers such as Renée Baillargeon of the University of Il­linois and Elizabeth S. Spelke of Harvard Uni­versity found that infants understand funda­mental physical relations such as movement tra­jectories, gravity and containment. They look longer at a toy car appearing to pass through a solid wall than at events that fit basic principles of everyday physics.

By the time they are three or four, children have elementary ideas about biology and a first understanding of growth, inheritance and ill­ness. This early biological understanding reveals that children go beyond superficial perceptual appearances when they reason about objects. Susan A. Gelman, also at Michigan, found that young children believe that animals and plants have an "essence"—an invisible core that stays the same even if outside appearances change.

For babies and young children, the most im­portant knowledge of all is knowledge of other people. Andrew N. Meltzoff of the University of Washington showed that newborns already un­derstand that people are special and will imitate their facial expressions.

In 1996 Betty Repacholi (now at Washington) and I found that 18-month-olds can understand that I might want one thing, whereas you want another. An experimenter showed 14- and 18-month-olds a bowl of raw broccoli and a bowl of goldfish crackers and then tasted some of each, making either a disgusted face or a happy face. Then she put her hand out and asked, "Could you give me some?" The 18-month-olds gave her broccoli when she acted as if she liked it, even though they would not choose it for themselves. (The 14-month-olds always gave her crackers.) So even at this very young age, children are not completely egocentric—they can take the per­spective of another person, at least in a simple way. By age four, their understanding of every­day psychology is even more refined. They can explain, for instance, if a person is acting oddly because he believes something that is not true. . .

The Statistics of Blickets

In 1996 Jenny R. Saffran, Richard N. Aslin and Elissa L. Newport, all then at the University of Rochester, first demonstrated this ability in stud­ies of the sound patterns of language. They played sequences of syllables with statistical regularities to some eight-month-old babies. For example, "bi" might follow "ro" only one third of the time, whereas "da" might always follow "bi." Then they played the babies new strings of sounds that either followed these patterns or broke them. Babies listened longer to the statistically unusual strings. More recent studies show that babies can detect statistical patterns of musical tones and visual scenes and also more abstract grammati­cal patterns.

Babies can even understand the relation be­tween a statistical sample and a population. In a 2008 study my University of California, Berke­ley, colleague Fei Xu showed eight-month-old babies a box full of mixed-up Ping-Pong balls: for instance, 80 percent white and 20 percent red. The experimenter would then take out five balls, seemingly at random. The babies were more surprised (that is, they looked longer and more intently at the scene) when the experiment­er pulled four red balls and one white one out of the box—an improbable outcome—than when she pulled out four white balls and one red one.

Detecting statistical patterns is just the first step in scientific discovery. Even more impres­sively, children (like scientists) use those statistics to draw conclusions about the world. In a version of the Ping-Pong ball study with 20-month-old babies using toy green frogs and yellow ducks, the experimenter would take five toys from the box and then ask the child to give her a toy from some that were on the table. The children showed no preference between the colors if the experi­menter had taken mostly green frogs from the box of mostly green toys. Yet they specifically gave her a duck if she had taken mostly ducks from the box—apparently the children thought her statis­tically unlikely selection meant that she was not acting randomly and that she must prefer ducks.

In my laboratory we have been investigating how young children use statistical evidence and experimentation to figure out cause and effect, and we find their thinking is far from being "pre­causal." We introduce them to a device we call "the blicket detector," a machine that lights up and plays music when you put some things on it but not others. Then we can give children pat­terns of evidence about the detector and see what causal conclusions they draw. Which objects are the blickets?

In 2007 Tamar Kushnir, now at Cornell Uni­versity, and I discovered that preschoolers can use probabilities to learn how the machine works. We repeatedly put one of two blocks on the machine. The machine lit up two out of three times with the yellow block but only two out of six times for the blue one. Then we gave the chil­dren the blocks and asked them to light up the machine. These children, who could not yet add or subtract, were more likely to put the high-probability yellow block on the machine.

They still chose correctly when we waved the high-probability block over the machine, acti­vating it without touching it. Although they thought this kind of "action at a distance" was unlikely at the start of the experiment (we asked them), these children could use probability to discover brand-new and surprising facts about the world. . .

These studies suggested that when children play spontaneously ("getting into everything") they are also exploring cause and effect and do­ing experiments—the most effective way to dis­cover how the world works. . .

The brain region called the prefrontal cortex is distinctive to humans and takes an especially long time to mature. The adult capacities for fo­cus, planning and efficient action that are gov­erned by this brain area depend on the long learning that occurs in childhood. This area's wiring may not be complete until the mid-20s.

The lack of prefrontal control in young chil­dren naturally seems like a huge handicap, but it may actually be tremendously helpful for learn­ing. The prefrontal area inhibits irrelevant thoughts or actions. But being uninhibited may help babies and young children to explore freely. There is a trade-off between the ability to ex­plore creatively and learn flexibly, like a child, and the ability to plan and act effectively, like an adult. The very qualities needed to act efficient­ly—such as swift automatic processing and a highly pruned brain network—may be intrinsi­cally antithetical to the qualities that are useful for learning, such as flexibility.

A new picture of childhood and human na­ture emerges from the research of the past de­cade. Far from being mere unfinished adults, ba­bies and young children are exquisitely designed by evolution to change and create, to learn and explore. Those capacities, so intrinsic to what it means to be human, appear in their purest forms in the earliest years of our lives. Our most valu­able human accomplishments are possible be­cause we were once helpless dependent children and not in spite of it. Childhood, and caregiving, is fundamental to our humanity. ■

Alison Gopnik is professor of psycholo­gy and affiliate professor of philosophy at the University of California, Berkeley. She has done groundbreaking research into how children develop a "theory of mind," the ability to understand that other peo­ple have minds and may believe or want different things than they do. She helped to formulate the "theory theory," the idea that children learn in the same way that scientists do. Investigations of chil­dren's minds, she argues, could help us resolve deep philosophical questions such as the mystery of consciousness.

Alison Gopnik's Web site: alisongopnik.com

Photographs by Timothy Archibald

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