I wish I could have read The Scientist in the Crib when my son was born. Authors Alison Gopnik, Andrew Meltzoff, and Patricia Kuhl discuss not only what babies do, but also how and why they do what they do. The three scientists investigate why babies flirt, what they hear when we speak to them, and why they prefer looking at stripes. They even try to study what babies think.

Gopnik, at the University of California at Berkeley, and Meltzoff and Kuhl, both at the University of Washington, write for everyone interested in the mind and brain. Their humorous treatment of controversies in science helps them succeed remarkably well at their goal "to let nonscientists understand developmental science."

They offer readers stories such as that of the Russian scientists Lev Vygotsky and his student Alexander Luria. In the 1930s, these researchers attempted to study the effect of literacy on cognition and perception. Vygotsky sent Luria to eastern Russia to determine whether illiterate Tatars experienced perceptual illusions.

"Luria, wildly excited by his results," the authors write, "couldn't wait . . . and telegraphed Vygotsky, 'Tatars have no illusions.'" He was immediately arrested; there was only one subject about which Tatars could have no illusions in Stalinist Russia. Later Luria "became a military brain surgeon at the front - it was safer. Vygotsky avoided the purges only by dying young. . . . A year after his death, Stalin . . . [outlawed] developmental psychology."

In discussing more recent revolutionary events in cognitive science, the authors explain how both sociological and technological factors have influenced the field. "So long as men dominated academia, developmental psychology was inevitably marginalized," they write. ". . . Until 1973 there were no women at all in the Berkeley psychology department. . . . The advent of women academics in the university helped to make studying babies and children seem respectable."

According to Gopnik and her coauthors, two technological advances revolutionized this field: the video recorder, as a tool to observe babies' nonverbal behavior, and the digital computer, to give it theoretical justification. I would add a third: the pill. It allowed women to finish their education before having children, and to limit family size. This gave women with academic careers time to observe each child.

The authors claim that the greatest conceptual breakthrough in thirty years is the idea that the brain is a kind of computer. Of course, scientists of every era have compared the brain to the most advanced technology of their day - a loom, a telephone switchboard, and now a computer. Nevertheless, the authors see the most recent comparison as the basis of the new field of cognitive science and posit that in the last thirty years we have learned more about what babies know than in the preceding 2,500 years.

The change in ideology is crucial: A scientist who views babies as small computers, as opposed to "slightly animate vegetables - carrots that could cry," expects more. With this shift in ideology, scientists can give the baby a precise, defined input that stimulates their senses (sight, hearing, and touch) and measures the output (reaction).

Looking at the brain as a biological computer, the authors suggest that "if cognitive psychologists are clever enough about giving babies the right kind of input, and about interpreting their output, we should be able to work out their program, too."

Scientists, for example, asked two questions: "Do babies think two things are the same or different?" and "Do they prefer one or the other?" To find out, researchers showed babies two objects, a picture of a face and a picture of a checkerboard, for example. An observer who could not see what the baby saw, recorded the infant's eye movements to see which picture the baby observed longer. Using these and similar techniques, scientists demonstrated that babies prefer human faces over other sights. Similar experiments indicated that babies prefer human voices over other sounds.

How much babies know surprised researchers. Twenty-five years ago, psychologists claimed that newborns have no developed cortex and only the simplest automatic responses. Even the eminent child psychologist Jean Piaget thought newborn babies have only reflexes.

Today, scientists think that babies' representations of the world are surprisingly complex. These representations permit babies to make predictions about the future. If there are discrepancies between their prediction and what happens, babies appear to be able to modify their rules and create new representations.

Young babies imitate adults, a trait that leads them to behaviors not genetically determined. Through imitation, children learn how to behave in their social world. Babies also imitate other children; in fact, older siblings are sometimes more important than parents in this regard. The authors claim that imitation is an innate mechanism for learning from adults, a method of learning not available to most other animals.

In a recent review in Science, however, primate researchers suggest that a chimpanzee's behavior may also be shaped by influences in the environment in which it is raised. They mention 39 behaviors that differ between separate groups. Perhaps the study of primate behavior, like that of babies' minds, awaits development of the appropriate ideology as well as the appropriate technology.

In the penultimate chapter, the authors discuss the brain development of children. A baby is born with most of the neurons it will ever have. The brain grows primarily because the number of connections between neurons, the number of synapses, increases. Synaptic activity can be estimated by measuring the amount of glucose the brain uses. Such measurements indicate that children's brains are much more active than those of adults. Synaptic activity reaches adult levels by about age two. Activity is twice the adult level at age three and remains high until age nine to ten. It starts to decline to adult levels by about age eighteen.

I'd like to see current data here from neurobiologists. Our preconceptions about neuronal loss with age, and the lack of neurogenesis in adults, have been overturned in the past few years. Scientists once thought that no neurogenesis took place in the adult brain, but now believe that neurons proliferate throughout life.

The Scientist in the Crib doesn't give parents a blueprint for how to raise their children, but it can help them make informed decisions. The authors explain that "There is a largely dishonorable history of 'expert advice' to mothers." This history included "male 'experts' ordering women around on the basis of a science that was supposed to be incomprehensible to them. . . . One benefit of knowing the science is a kind of protective skepticism. . . . Knowing about science immunizes us from pseudoscience."

Reading this book can empower parents. The authors combine an appropriate blend of theory and fact with amusing anecdotes and lively, engaging stories to convey their points. They describe a paradigm shift - from viewing babies as "crying carrots" to viewing them as biological computers and something worth studying.

A woman wrote to the list server for the National Association of Science Writers that she was attending another baby shower and wanted to give something other than a rattle or baby outfit: "Could we suggest a good book for prospective parents." I immediately wrote back, recommending The Scientist in the Crib. Another woman also suggested this book. So if you don't buy it for yourself, you can buy it as a baby-shower gift and sneak in a few pages of reading before giving it away.