An Iowa State University psychology professor has completed a massive study which he says proves exposure to violent video games produces more aggressive behavior in kids. Craig Anderson says the study involved analyzing 130 research reports from around the world. The reports measured levels of aggression among elementary school children on the first day of school and again several months later.

“Then, we were able to look and see if their video game habits measured early in the school year predicted increases or decreases of aggressive behavior over the course of the school year,” Anderson said. The study was published this week in the new issue of Psychological Bulletin, an American Psychological Association journal. Anderson says the team of researchers also found children who were naturally aggressive to begin with were not necessarily more inclined to play violent games.

“What the evidence currently shows is that the violent games cause an increase in the likelihood of later aggressive behavior,” Anderson said. “There’s not much evidence aggressive kids, being aggressive early, sort of predicts an increase in playing violent games later on.” Anderson isn’t suggesting every child who plays violent video games will become a serial killer, but says exposure to media violence should be easier to control than other risk factors.

“The interesting thing to me about the media violence risk factor compared to the others is that media violence is something that a parent can do something about…whereas a lot of the other risk factors are things a parent can’t control,” Anderson said. The study shows violent video game effects are significant across all cultures, in males and females and in all age groups. Anderson made his comments on the Iowa Public Radio program The Exchange.