Games and aggression have been a hotbutton item for years, and the controversy isn't going away any time soon. Some of it is fueled by conservative paranoia and some by justifiable parental angst. Nevertheless, as Richard pointed out recently, it doesn't mean that the questions are automatically without merit. So I give you this to chew on--a study of gaming and violence that specifically tested an MMOG, did it out of a lab and used a control group:
Hot off the presses as of yesterday in a mainstream, peer-reviewed journal:
Williams, D. & Skoric, M. (2005). Internet Fantasy Violence: A Test of Aggression in an Online Game. Communication Monographs, 22(2), p. 217-233.
Research on violent video games suggests that play leads to aggressive behavior. A longitudinal study of an online violent video game with a control group tested for changes in aggressive cognitions and behaviors. The findings did not support the assertion that a violent game will cause substantial increases in real-world aggression. The findings are presented and discussed, along with their implications for research and policy.
You can download the article from the Taylor & Francis website. The less ethical might look here. I hope that readers here will take the results in context. This is one game and other titles may differ. It's also not a test of young children, but is rather a typical MMOG sample with a broader age range. And (he hints), other research coming out of this same study shows that the game has other effects that are both good and bad. I'll save that for another post.
Personally, I'm still very agnostic about the range of effects that "games" may have. I think that a solid longitudinal test of children probably will show aggression effects (once someone does one), and a host of positives as well. To my mind, they aren't mutually exclusive.