A new study shows that there is a definite correlation between violent video games and violent behavior in children. It was a big problem trying to find out if the games actually make kids violent, or already-violent kids are the ones playing games like these. Three long-term studies conducted in the United States and Japan prove that otherwise peaceable kids can become more aggressive in school after playing violent video games. The results were published in the Pediatrics medical journal, and they showed the same correlation in all three samples, and the difference in American and Japanese culture didn’t seem to have any effect.

The younger kids seem to be more affected, as children between the ages of 9 and 12 exhibit more aggressive changes than the kids between the ages of 13 and 18. The study might prove wrong after all, and that’s because another research conducted by Australian researcher Grant Devilly last year showed that there’s no evidence to link violence and video games. Devilly found that kids who are predisposed to violence are likely to change behavior after playing a violent game. The study conducted this year consisted of two phases. One involved a group of teenagers playing video games and the second one required the teenagers to complete a survey in order to determine their levels of aggressive behavior several months later.

The results suggest that, even in the two very different cultures, there was a significant correlation between the use of violent video games and physical aggression and that frequent playing of violent games is an important causal risk factor for youth aggression.