http://www.ted.com/talks/daphne_bavelier_your_brain_on_video...
http://psych.utoronto.ca/users/spence/Research_Games.html
Anyways, I tried to approach this study as objectively as I could. But I have some gripes with their methods and more importantly, their conclusions.
> Students in the study then participated in a competitive reaction time task, which is used to measure aggression. Each student was told that he or she would compete against an unseen opponent in a 25-trial computer game in which the object was to be the first to respond to a visual cue on the computer screen.
The loser of each trial would receive a blast of unpleasant noise through headphones, and the winner would decide how loud and long the blast would be. The noise blasts were a mixture of several sounds that most people find unpleasant (such as fingernails on a chalk board, dentist drills, and sirens). In actuality, there was no opponent and the participants were told they won about half the trials.)
So this study took people playing competitive, violent video games, and then measured their aggression by giving them another competitive, violent game? After three days, they say the students were choosing to deliver harsher and harsher sounds to their "opponents." But after three days, certainly these students had also been given their fair share of harsh sounds, and at that point it's not crazy to think that they were just "playing the game."
Another method they used to measure aggression:
> They were given the beginning of a story, and then asked to list 20 things that the main character will do or say as the story unfolds. For example, in one story another driver crashes into the back of the main character’s car, causing significant damage. The researchers counted how many times the participants listed violent or aggressive actions and words that might occur.
So after they played a violent yet fake video game that they likely found to be fun, you give them a fake story and they pick violent outcomes? They were likely still in the mindset of playing the game that they found fun.
None of this conclusively shows anything about their long term aggression in the real world. It seems to be using fake scenarios (with poor timing) to try and make real-world conclusions.