A paper was recently published in the March 2010 issue of the Psychological Bulletin documenting a study done on the effects of violent video games on children. One of the contributors was Prof. Bushman of UM.
Some of the conclusions reached in the paper are as follows: "We believe that debates can and should finally move beyond the simple question of whether violent video game play is a causal risk factor for aggressive behavior; the scientific literature has effectively and clearly shown the answer to be “yes.” Instead, we believe the public policy debate should move to questions concerning how best to deal with this risk factor. Public education about this risk factor—and about how parents, schools, and society at large can deal with it—could be very useful (171).
The paper can be accessed by university affiliates through this link.