Teachers of 600 8th and 9th graders, aged 13 to 15, said children who spent more time playing violent video games were more hostile than other children and more likely to argue with authority figures and other students.

The study also shows that children who play violent video games are much less likely to be helpful to others than they are when they play more social and non-violent video games.

"But the real issue is whether there's long-lasting change as a result of these violent video games, and the current literature does not adequately address these issues," says Kevin Kieffer f Saint Leo University in Saint Leo, Florida, who also worked on the study.

"Violence in video games appear to have similar negative effects as viewing violence on TV, but may be more harmful because of the interactive nature of video games," said Dr. Elizabeth Carll, co-chair of the APA's six-member video game violence group, in a statement announcing the study. "Playing video games involves practice, repetition and being rewarded for numerous acts of violence, which may intensify the learning. This may also result in more realistic experiences which may potentially increase aggressive behavior."

Douglas Lowenstein, president of the Entertainment Software Association, the trade group that represents the U.S. computer and video game industry, charged the APA with disregarding credible research and analysis which challenge claims that video games cause aggression or crime reports MSNBC

"This resolution is hardly surprising since the APA has made it clear over a long period of time that it believes violent video games are harmful and thus justify enactment of unconstitutional restrictions on First Amendment freedoms," Lowenstein said in a statement.