A study involving Unreal Tournament players, given a cash incentive for winning, found that gamers' testosterone levels spiked noticeably after pwning complete strangers. When defeating friends, they produced even less testosterone than their vanquished teammates.
The study's results imply that video games draw on physiological mechanisms in ways similar to warfare, where testosterone-fueled aggression provides a strong advantage. Researchers had tried studying it on subjects in sports, but the natural production of testosterone by physical exertion clouded the results of the study.
In this one, researchers pitted 14 three-player teams against one another in Unreal Tournament 2004's Onslaught - a capture-the-flag mode - and laid a $45 bounty for winning team players vs. $15 for losers. To make sure they knew what they were doing, they let the teams practice for a week.
Afterward, they found that winning teams' testosterone levels spiked immediately after the tournament, especially in those who contributed most to the win. When team members played one another, in death matches with similar cash incentives, the best performing males typically produced less testosterone than those they defeated.
"In a serious out-group competition you can kill all your rivals and you're better for it," said David Geary, an evolutionary psychologist at the University of Missouri. But when competing against others in order establish a social hierarchy, annihilation doesn't make sense. "You can't alienate your in-group partners, because you need them," he said.
Gamers Are More Aggressive to Strangers [New Scientist]