As part of a companion site to a PBS series on videogames, MIT professor Henry Jenkins wrote an essay debunking eight common myths about videogames. He has an especially succinct debunking of the claim that videogames encourage real world aggression and violence,
Claims like this are based on the work of researchers who represent one relatively narrow school of research, “media effects.” This research includes some 300 studies of media violence. But most of those studies are inconclusive and many have been criticized on methodological grounds. In these studies, media images are removed from any narrative context. Subjects are asked to engage with content that they would not normally consume and may not understand. Finally, the laboratory context is radically different from the environments where games would normally be played. Most studies found a correlation, not a causal relationship, which means the research could simply show that aggressive people like aggressive entertainment. That’s why the vague term “links” is used here. If there is a consensus emerging around this research, it is that violent video games may be one risk factor – when coupled with other more immediate, real-world influences — which can contribute to anti-social behavior. But no research has found that video games are a primary factor or that violent video game play could turn an otherwise normal person into a killer.