Researchers say they may have explained why some studies show that violent video games make players more aggressive, while others don't: it's all in the style of play.
Two separate studies indicate that college students who teamed up to play violent video games cooperated more afterwards, and were less aggressive, than those who played competitively.
"Clearly, research has established there are links between playing violent video games and aggression, but that's an incomplete picture," says David Ewoldsen of Ohio State University.
"Most of the studies finding links between violent games and aggression were done with people playing alone. The social aspect of today's video games can change things quite a bit."
One study involved 119 college students who played Halo II with a partner, either competitively or cooperatively. After playing, the same pairs took part in a real-life game where they had the opportunity to cooperate or compete with each other - and those who played the video game cooperatively were more likely to cooperate in the real-life game too.
"These findings suggest video game research needs to consider not only the content of the game but also how video game players are playing the game," says graduate student in communication at Ohio State John Velez.
A second study goes one step further by showing that cooperating in playing a violent video game can even unite people from rival groups – in this case, fans of Ohio State and those of the University of Michigan.
Eighty Ohio State students were paired with a person who they thought was another student participant - actually, one of the experimenters wearing a university T-shirt.
The pair then played the highly realistic and violent first-person-shooter video game Unreal Tournament III together, either as teammates or as rivals.
Afterwards, they played the same real-life game used in the previous study with their supposed partner, and also completed tasks that measured how aggressive they felt.
And, as in the first study, players who cooperated in playing the video game later showed more cooperation than those who competed against each other - even when Ohio State participants thought they were playing with a rival from the University of Michigan.
"The point is that the way you act in the real world very quickly overrides anything that is going on in the video games," says Ewoldsen. "Video games aren't controlling who we are."