Video games are the subject of so many studies, not to mention findings. Some suggest cognitive benefits, others behavioral issues that may or may not persist over time.

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Many of these studies are small enough to require further investigation, and the journalists reporting on them often confuse correlation (when results happen in tandem) with causation (when one action is shown to result from another).

A new study out of Ohio State University suffers from a small sample size (70 participants), but its findings -- that people who play violent video games for three consecutive days show increases in aggression and hostility with each day played -- are compelling enough to warrant larger studies.

"It's important to know the long-term causal effects of violent video games because so many young people regularly play these games," Brad Bushman, co-author and professor of communication and psychology, said in a school news release. It "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."

To study this potentially cumulative effect, which Bushman and colleagues report on in the Journal of Experimental Social Psychology, researchers told 70 French university students that they would be participating in a three-day study on the effects of video game brightness on visual perception. The students were assigned to play, in random order, one game per day for 20 minutes, with some playing violent video games (Call of Duty 4, Condemned 2, and The Club) and others nonviolent ones (S3K Superbike, Dirt2, and Pure).

After playing each day's randomly assigned game, the researchers measured hostile expectations by giving the students the beginning of a story and asking them to list 20 things the main character would say or do in the story. The researchers then tallied how many times the participants anticipated violent or aggressive actions.

The students who had played violent video games were more likely with each passing day to think the characters would go on to behave aggressively or violently. Those who had played nonviolent video games, meanwhile, did not increase their expectations of hostility.

The researchers also measured aggression by having the students compete in a reaction time task. Each student was told that he or she would be going up against an unseen opponent in a computer game to see who responded faster to a visual cue on the screen. The player would receive a blast of noise through the headphones with each loss and determine the volume and duration of the blast of noise for the opponent with each win. (The noise blasts combined sirens, dentist drills, fingernails on a chalk board, etc.)

There were, of course, no actual opponents, and the player was made to think he or she was winning about half the time. And while those who had played nonviolent video games continued to blast their "opponent" with roughly the same volume and duration of noise each day, those who had played violent ones increased the volume and duration of that noise with each passing day.

Bushman so firmly believes that the violent video games are the cause of this increase in aggression and hostile expectations that he says testing players for longer periods of time is neither practical nor "ethical."

"I would expect that the increase in aggression would accumulate for more than three days," he says. "It may eventually level off. However, there is no theoretical reason to think that aggression would decrease over time, as long as players are still playing the violent games."

Because many people who play violent video games are not doing so in 20-minute spurts for just three consecutive days, and since the sample size of this study is so small, the long-term cumulative effects of violent video games remains unknown.

But Bushman adds: "There is no theoretical reason to think that aggression would decrease over time, as long as players are still playing the violent games."