''Life on the Screen'' is a book not about computers, but about people and how computers are causing us to reevaluate our identities in the age of the Internet. We are using life on the screen to engage in new ways of thinking about evolution, relationships, politics, sex, and the self. ''Life on the Screen'' traces a set of boundary negotiations, telling the story of the changing impact of the computer on our psychological lives and our evolving ideas about minds, bodies, and machines. What is emerging, Turkle says, is a new sense of identity-- as decentered and multiple. She describes trends in computer design, in artificial intelligence, and in people's experiences of virtual environments that confirm a dramatic shift in our notions of self, other, machine, and world. The computer emerges as an object that brings postmodernism down to earth.