Virtual reality: danger ahead.

• Author: Kershner, Kelly

WAR HAS BEEN declared. You are seated in an M-1 tank simulator. A bulky, heavy set of gogles called a head-mounted display--a souped--up version of your childhood ViewMaster toy--is strapped over your eyes; a helmet fits snugly on your head. As you sit, the head-mounted display flashes computer-generated images of the battlefield into each eye, images that differ enough to give the impression of depth. You look around, evaluating the situation. The helinet--embedded with sensors--picks up your eye and head movements and relays them to the computer, which changes the scene accordingly.

An enemy tank fires from the south. You reach for the controls to make an evasive maneuver; sensors pick this up, too, and the view of the battle field changes as your tank "moves." The fighting continues. When it's all over, you tally up the soldiers "kill" and "wounded," the property "damaged" or "destroyed." It wasn't a great showing for your side, but no matter--there are five more runs scheduled for today. You are bound to improve. You will work at warfare until you get it right. Welcome to virtual reality, the up-and-coming technology that allows users to interact with computer-simulated images and some day may offer immersion and escape into make-believe worlds.

In today's virtual worlds, surgeons cut into computer-simulated legs to practice tricky tendon transfer operations. Golfers keep their game up to par in the off-season by teeing up on fake fairways. People plagued by phobias confront their fears by crossing ersatz bridges and handling simulated snakes. Architects walk around in virtual buildings, checking them for accessibility for the handicapped and code violations before a single brick is laid.

The virtual realities of the future will be even more spectacular, experts say. Ten, 20, or 100 years from now, they predict, neurosurgeons will practice operations on simulated tissues programmed to respond as real brain tissues do. Students will learn astronomy by jumping from planet to planet or chemistry by walking around inside an atom. Tourists will take trips to the past. Car shoppers will try out the virtual model before buying the real one. Handicapped citizens, even those who barely can move, will participate in mainstream society by working virtually; a mere flick of the mouse or joystick will perform an action in the virtual world that will be mimicked by a "tele-robot" in the real one.

Virtual reality's benefits--both real and potential--are clear. Less clear, though, are its possible side effects on individuals, groups, and/or society itself. Will VR be the new television, its content dictated by advertising revenues? How will virtual voyages affect...