SOME children think computers are alive, writes Sherry Turkle, an MIT sociologist and psychologist, in this engaging book. Other children disagree, or settle on "sort of." But they are not sure. After all, computers talk, teach, play games, often win -- sometimes even cheat. "And if you cheat, you're alive," a 7-year-old boy told her.

Turkle suggests that, in this way, computers are now turning many of our youngest children into philosophers who argue about such questions as, does this machine know what it is doing? Does it have intentions, feelings? And how does it differ from us?

"In the children's distinctions we hear 'child versions' of how adults talk when they debate issues of computers and mind," she writes. Her book spans both kinds of reactions. It is the result of a six-year study during which she observed over 200 children between the ages of 4 and 14 and over 200 adults -- from video-game enthusiasts to hackers, from ordinary users of computers to leaders in the field of artificial intelligence. She succeeds very well in showing how our encounters with computers are shaping us -- how "a generation develops a style."

Some of these encounters begin very early. She describes how 4-year-olds get caught up in learning how to do math with the aid of a computer program called Logo in nursery school. She shows how the mastery of writing or programming can boost the self-confidence of older children. And she shows how much children differ in their approaches to computers.

Girls tend to use what she calls "soft mastery," like a painter who stands back between brushstrokes, looks at the canvas and then decides what to do next. Boys are more likely to use "hard mastery," imposing their will over the machine by implementing a plan. Some children spend most of their time making attractive designs or writing stories, while others seem driven to figure out exactly how to make certain programs work.

Despite such differences, nearly all children respond to the computer's "holding power," its ability to give instant feedback in an almost human fashion. They are deeply attracted to this machine which reacts to them so quickly and does what they want. At the same time, the machine forces them to enter into what Turkle calls "the construction of the psychological" -- an increasingly nuanced way of thinking about mental life.

For example, very young children usually decide whether something is animate or inanimate according to whether it can move of its own accord, but even young children realize that such physical or mechanical criteria are irrelevant when dealing with computers. So they have to look for other kinds of criteria -- mental or emotional ones.

Turkle is fascinated by this new trend among the young, as well as by the obvious discomfort of many adults when faced with the idea that superintelligent computers may some day serve as psychotherapists, judges or physicians. At all ages, she maintains, people feel challenged by computers to look at themselves and their own minds. This forces them to grapple with some of the oldest philosophical questions -- the idea of free will and the definition of a self -- as well as to ask how close their own thinking is to that of a machine. One of the most entertaining and stimulating parts of this book is Turkle's account of the present controversy over whether computers can ever do more than they have been told to do. No, says the philosopher John Searle; no matter what feats of intellect computers perform, they will never be thinking -- they will only be simulating thought. Yes, say some of the boosters of artificial intelligence: if computers are programmed to learn and to make their own decisions, many unpredictable things can happen. These scientists believe that the human mind itself is nothing but a wondrously complex machine.

Turkle had never touched a computer before starting on the study that led to The Secret Self. However, she had written a book, Psychoanalytic Politics, which described "how France, a country traditionally resistant to psychoanalytic ideas, had been swept by an 'infatuation with Freud' in the late 1960's. . . . There was a fit between a psychoanalytic way of thinking and a social demand" in France in those days, she explains in her current book. "Psychoanalytic language spread into the rhetoric of political parties, into training programs for schoolteachers, into advice-to-the-lovelorn columns. I became fascinated with how people were picking up and trying on this new language for thinking about the self."

Something analogous is now happening in the United States, she claims. But instead of borrowing ideas from psychoanalysis, people are now using metaphors drawn from programming, cybernetics and information processing to think about politics, education, social process and themselves.

Recently she overheard one young woman referring to psychotherapy as "debugging." Another woman talked about having to "reprogram herself" to live alone. These are signs of the times, Turkle believes, signs of a new Zeitgeist now being formed around our increasingly close relationships with our personal computers.