Parents worry - Tony Blair included, according to a recent interview - about the atmosphere of violence that confronts our children, including their immersion in violent recreation. The results of two studies published in the Journal of Personality and Social Psychology demonstrate that even brief exposure to violent video games increase aggressive tendencies in the short term and can have long-lasting effects. Students who reported playing more violent video games engaged in more aggressive behaviour and had poorer school performance. In one study, students were asked to punish a human subject by exposing them to a blast of noise. After playing violent video games, the students punished their human subjects for longer periods of time. Think about that the next time you fork out £40 for a game like Wolfenstein €3, Myst or Unreal Tournament.