A Lot Of Games

"There has been a lot of attention wasted in figuring out whether these things turn us into killing machines," said computational analyst Joshua Lewis at the University of California in San Diego, who studied 2,000 computer game players. "Not enough attention has been paid to the unique and interesting features that videogames have outside of the violence."

Broadly speaking, today's average gamer is 34 years old and has been playing electronic games for 12 years, often up to 18 hours a week. By one analyst's calculation, the 11 million or so registered users of the online role-playing fantasy World of Warcraft collectively have spent as much time playing the game since its introduction in 2004 as humanity spent evolving as a species—about 50 billion hours of game time, which adds up to about 5.9 million years.

With people playing so many hundreds, if not thousands, of different games, though, university researchers have been hard-pressed to pinpoint the lasting effects on cognition and behavior.

Blizzard Entertainment Inc. in Irvine, Calif., which sells World of Warcraft, StarCraft II and other popular games, did not respond to queries about whether the company supports gaming research or conducts its own studies. Neither did RiotGames Inc. in Santa Monica, which markets League of Legends.

Different Games' Effects on Your Brain

Computer gaming has become a $25 billion-a year entertainment business behemoth since the first coin-operated commercial videogames hit the market 41 years ago. In 2010, gaming companies sold 257 million video and computer games, according to figures compiled by the industry's trade group, the Entertainment Software Association.

For scientists, the industry unintentionally launched a mass experiment in the neurobiology of learning. Millions of people have immersed themselves in the interactive reward conditioning of electronic game play, from Tetris, Angry Birds, and Farmville, to shooter games and multiplayer, role-playing fantasies such as League of Legend, which has been played 1 billion times or so in the two years since it was introduced.

"Videogames change your brain," said University of Wisconsin psychologist C. Shawn Green, who studies how electronic games affect abilities. So does learning to read, playing the piano, or navigating the streets of London, which have all been shown to change the brain's physical structure. The powerful combination of concentration and rewarding surges of neurotransmitters like dopamine strengthen neural circuits in much the same the way that exercise builds muscles. But "games definitely hit the reward system in a way that not all activities do," he said.