"New research from Ohio State finds that players who engage in cooperative play in games like Call of Duty and Halo show increased cooperative behavior later - as opposed to aggressive behavior. The research was co-authored by OSU Professor of communication David Ewoldsen and was comprised of several studies.
The first study had students play the video game Halo 2 for 20 minutes in separate rooms, with each given four contrasting play conditions. In the cooperative condition, subjects played the game as teammates against computer aliens. In the direct competition condition, they played against each other. In the indirect competition, they played the game solo. In the last condition, they did not play the game until much later, after they filled out a survey for measures of cooperation.", writes GamePolitics.