This scenario is part of a new virtual reality system developed by researchers to help soldiers who are suffering from post-traumatic stress disorder (PTSD) brought on by their service in the Iraq war.

The goal of the system is to gradually expose the returning soldiers -- by wearing the system's goggles and head phones -- to the sights, sounds and smells that traumatized them in Iraq, said Albert "Skip" Rizzo, research assistant professor at the Institute for Creative Technologies at the University of Southern California. The exposure should help ease the PTSD symptoms, he said. The Institute is developing the system jointly with the U.S. Navy's Office of Naval Research.

Since beginning clinical trials using the system at the end of last year, six soldiers have been treated on it, Rizzo said. Four of those have seen "dramatic improvements," he said. In fact, he added, one of the treated soldiers has returned to Iraq, and a second will soon go back.

The virtual reality system is based on a video game called Full Spectrum Warrior that was developed by the Army as a training tool. The researchers added graphics, sounds, vibrations and smells to the original game to create various scenarios mimicking those experienced by soldiers in Iraq, Rizzo said.

The scenarios include soldiers being shot at by insurgents, crashing in a helicopter or witnessing a bomb exploding or a fellow soldier being shot. To help make the experience more real, the platform where the soldier sits can vibrate during a humvee ride and provide the smell of human sweat, gunpowder or burning rubber, Rizzo said.