For years, researchers have been trying to tease out the relationship between video-game violence and aggressive behavior. A study published last month in the American Psychological Association journal Psychology of Violence indicates it might not be the games' violent content that sparks aggression but instead their level of competitiveness.

In a series of small experiments involving college undergraduates, researchers had participants play one of two games that were equally matched for competitiveness, difficulty and pace, but one of the games was substantially more violent than the other. The students were told the experiment was about eye movement, not aggression.

Afterward, the students were asked to prepare a hot-sauce mixture for someone who they knew disliked hot and spicy food. Those who played the violent video game were no more likely to create a large quantity of spicy food -- an act that has been established in psychological research as being aggressive -- than those who played the nonviolent game.

In a second experiment, games were selected on the basis of how competitive they were. After the game playing, participants again took part in the "hot-sauce paradigm" task. Those whose games had been determined to be more competitive were far more likely to create large quantities of very spicy sauce for their poor tasters.