Violent videogames offer some teen players much-needed relief from stress. (Photo: Robert Couse-Baker/Flickr)

Sixteen-year-old Evan Jones played his first violent videogames when he was 3. He slew demons in Diablo II, blasted Lovecraftian horrors in Quake and shot terrorists in Counter-Strike.

If you buy conventional wisdom, by now Jones should be a tightly wound coil of aggression, ready to attack someone at the slightest provocation. Instead, he’s a pretty laid-back kid.

“[I get] an adrenaline rush during the game, and the need to win, but afterwards it’s just fine,” the San Francisco Bay Area ...