Violent video games and school

It found that children who played more violent video games early in the school year changed to see the world in a more aggressive way, and became more verbally and physically aggressive later in the school year -- even after controlling for how aggressive they were at the beginning of the study. Higher aggression and lower pro-social behavior were in turn related to those children being more rejected by their peers.

"I was startled to find those changes in such a short amount of time," said Gentile. "Children's aggression in school did increase with greater exposure to violent video games, and this effect was big enough to be noticed by their teachers and peers within five months."

The study additionally found an apparent lack of "immunity" to the effects of media violence exposure. TV and video game screen time was also found to be a significant negative predictor of grades.

The book's final chapter offers "Helpful Advice for Parents and Other Caregivers on Choosing and Using Video Games." The authors say that providing clear, science-based information to parents and caregivers about the harmful effects of exposure to violent video games is the first step in helping educate the people who are best able to use the information. The advice includes links to Web sites about entertainment media and parenting issues, including Anderson's and Gentile's Web pages at http://www.psychology.iastate.edu/faculty/caa/ and http://www.psychology.iastate.edu/faculty/dgentile/.