Could it be? Could playing video games, long blamed by parents for turning their teens into fat, lazy bums, be good for something? Studies have linked nonstop video gaming to such ills as carpal tunnel syndrome and tennis elbow, not to mention the current obesity epidemic plaguing this nation's young.

On the positive side, some research has shown that playing video games can improve eye-hand coordination and visual attention—the ability to search for a target in a jungle of objects, to monitor several items at once, and to keep track of a steady stream of objects zipping swiftly by.

And now comes more good news for video game aficionados. A new study, set to be published in the journal Psychological Science, shows that playing fast-paced, action-filled video games significantly sharpens vision, enabling gamers to see tiny, tightly packed letters more clearly.

The reason? "Action video game play changes the way our brains process visual information," says study author Daphne Bavelier, noting that after just 30 hours, video gamers showed "a substantial increase in the spatial resolution of their vision." Translation: "They could see figures like those way down on an eye chart more clearly," she says, "even when other symbols crowded in."

Bavelier, an associate professor of brain and cognitive sciences at the University of Rochester, says the findings are helping scientists design a way to aid people with amblyopic or "lazy" eye. Amblyopic patients often have trouble discerning normal-size font in a clutter of other letters (such as in newspapers) in much the same way that others might have difficulty reading the fine print in ads and on pill packaging (because the letters seem to collide or run into one another).

"We think action video game playing trains the same part of the visual cortex (located in the back of the brain) as that which has a dysfunction in people with lazy eye," Bavelier says. "This is showing us a new path forward for rehabilitation. By combining more traditional methods for doing rehabilitation with these games, we should be in a better position to reopen the visual cortex to learning."

Bavelier says that she and grad student Shawn Green pretested subjects to determine their ability to identify a central letter, in this case a "T," nestled amid a crowd of "flankers," or distracting symbols. "The ability to read that central letter deteriorated as we brought the letters closer together," she says. "We measured the smallest distance between the letters at which they could still perform at an 80 percent success rate."

The subjects—an equal mix of male and female college students who did not typically play action or sports video games—were then split into two groups: One played Unreal Tournament, a quick-paced, shoot-'em-up video game with loads of visual clues (that forced players to make super-quick, visually based decisions to survive); the other played Tetris, a more low-key video game that required equal agility but was not nearly as visually busy or demanding.

Researchers tested subjects' vision again after a minimum of five hours of play weekly for six weeks. The results: "We found that the Unreal Tournament players could still perform at 80 percent correct when we brought the flankers closer together," but Tetris gamers showed no improvement, Bavelier says.

She notes that researchers were surprised by the findings, because it was previously believed that the adult visual cortex could not easily be retrained or taught new things. And yet, the results indicate that is exactly what happened.

"We're trying to find out how much plasticity the visual cortex is capable of," she says. "Previous work shows that if you are trained to detect moving patterns, you detect these specific motions better. Some learning is taking place, but it is very specific to the conditions under which you have been trained."

"What is surprising here," she adds, "is that we see the effect of training extending beyond what the subjects were trained to do, which contradicts the current school of thought. ... These games push the human visual system to the limits and the brain adapts to it. That learning carries over into other activities and, possibly, everyday life."

But lest you think that is an excuse to start playing video games all the time—forget it. "There's more to life than vision," Bavelier chuckles. Besides, she notes, obsessive play will not necessarily lead to benefits, even in people with lazy eye. "It needs to be done properly," she says about integrating video games into a treatment plan. "Usually people only have one amblyopic eye. We need to train the bad eye to become better, and the two eyes need to work together."