All those hours spent playing video games might not be wasted time after all: A new study suggests action-packed video games such as "Grand Theft Auto III" and "Counter-Strike" might actually sharpen students' minds.

Researchers at the University of Rochester in New York found that young adults who regularly played video games full of high-speed car chases and blazing gun battles showed better visual skills than those who did not. For example, they kept better track of objects appearing simultaneously and processed fast-changing visual information more efficiently.

To rule out the possibility that visually adept people are simply drawn toward video games, the researchers conducted a second experiment. They found that people who do not normally play video games but were trained to play them developed enhanced visual perception.

Exactly why video games have this effect is not clear. The researchers said more study is needed.

They said the findings suggest that video games could be used to help visually impaired patients see better or to train soldiers for combat.

The study was published in the May 29 issue of the journal Nature and was led by Daphne Bavelier, an associate professor of brain and cognitive sciences.

Parent groups and anti-violence advocates contend that the bloodshed in some video games triggers aggressive behavior in young people, as some hotly disputed studies have suggested. They blame violent video games for such crimes as the 1999 Columbine High School massacre.

The new study did not directly address how video violence affects behavior. Instead, the experiments focused on a person's ability to recognize and interpret symbols and letters after playing video games.

"Some people think that video games are turning kids into supergeniuses or psychokillers," said Kurt Squire, an educational game designer at Massachusetts Institute of Technology's Games-To-Teach Project, who was not part of the study. "The reality is probably close to this, where people can process visual information much quicker and be able to discern between different types of information."

Soldiers who grow up playing video games do better in processing information on a screen or operating long-range unmanned aerial vehicles that can film or photograph enemy activity on the ground, according to military experts.

"There are some very avid video gamers in the military. The people who have been playing video games all their lives seem a lot more comfortable in some of these kinds of environments," said Lt. Cmdr. Russell Shilling of the MOVES (Modeling, Virtual Environments, and Simulation) Institute at the Naval Postgraduate School in Monterey, Calif.

In the Rochester study, 16 men ages 18 to 23 took a series of tests that measured their ability to locate the position of a blinking object, count the number of simultaneous objects on a screen, and pick out the color of an alphabet letter. Those who played video games for the previous six months performed better in all those tests than those who did not.