Playing "action" video games improves a visual ability crucial for tasks like reading and driving at night, a new study says.

The ability, called contrast sensitivity function, allows people to discern even subtle changes in shades of gray against a uniformly colored backdrop. It's also one of the first visual aptitudes to fade with age.

That's why a regular regimen of action video game training can provide long-lasting visual power, according to work led by Daphne Bavelier of the University of Rochester.

Games for Better Vision

Previous research shows that gaming improves other visual skills, such as the ability to track several objects at the same time and paying attention to a series of fast-moving events, Bavelier said.

"A lot of different aspects of the visual system are being enhanced, not just one," she said.

The new work suggests that playing video games could someday become part of vision-correction treatments, which currently rely mainly on surgery or corrective lenses.

"Once you've had eye surgery or get corrective lenses, exposing yourself to these games should help the optical system to recover faster and better," Bavelier said.

"You need to retrain the brain to make use of the better, crisper information that's coming in" as a result of your improved eyesight, she added. (Explore a virtual brain.)

Shoot-'Em-Ups vs. Sims

Expert action gamers in the study played first-person shooters Unreal Tournament 2004 and Call of Duty 2. A group of experienced nonaction gamers played The Sims 2, a "life simulation" video game.

The players of nonaction video games didn't see the same vision benefits, the study says.

Bavelier and others are now trying to figure out exactly why action games in particular seem to sharpen visual skill.

It may be that locating enemies and aiming accurately is a strenuous, strength-building workout for the eyes, she said.

Another possible reason is that the unpredictable, fast-changing environment of the typical action game requires players to constantly monitor entire landscapes and analyze optical data quickly. Finally, Bavelier said, the games' rich payoff may also play a role.

"It's pleasing to be successful in your mission," she said. "When you combine rewards with these other [factors], then you get much more learning."