As lifelong gamers ourselves, we've never believed there's a link between violent video games and real-life aggression. But a new study out of Ohio State University says gaming for just a short period of time is enough to increase hostile behavior. Suddenly, we have the inexplicable urge to punch something.

The study shows that playing a violent game for just 20 minutes a day over the course of three days is enough to increase long-term aggressive behavior. It also shows that non-violent games, such as racers, seem to have no effect.

Lead study author Professor Brad Bushman says the long-term effect of violent games is similar in some ways to smoking: "Playing video games could be compared to smoking cigarettes. A single cigarette won't cause lung cancer, but smoking over weeks or months or years greatly increases the risk. In the same way, repeated exposure to violent video games may have a cumulative effect on aggression," he said.

In the study, 70 French college students were asked to play either violent or non-violent games. Those who played bloody, first-person shooters like Call of Duty 4: Modern Warfare were more likely to expect aggression from others and respond in kind.

"People who have a steady diet of playing these violent games may come to see the world as a hostile and violent place," said Bushman. "That expectation may make them more defensive and more likely to respond with aggression themselves."

And, what's more, Bushman theorizes the effect is cumulative, but he says it's "impossible" to know how aggressive someone might become after playing violent games for years. Still, he thinks a gamer's violent tendencies may "level off" over time.