Based on two studies by researchers Craig A. Anderson of the University of Missouri-Columbia and Karen E. Dill of Lenoir-Rhyne College, the article claims that violent video games increase aggressive tendencies in the short term and can have long-lasting effects. But the report's claims have met with cool response from British academics. "Even brief exposure to violent video games can temporarily increase aggressive behaviour," the psychologists said in a statement. A year ago, 13 people were killed and 23 wounded when two students at Columbine High School in Littleton, Colorado, went on a killing spree that ended only when they turned their guns on themselves. Because of the killers' penchant for playing the first-person shooting game "Doom," some believe violent video games should be blamed, at least in part, for the violence. The report outlines two psychology studies that support the theory of a link between playing violent video games and aggressive behaviour. The first, involving 227 college students, measured the students' aggressive tendencies and linked those tendencies to the student's video-game playing habits. "We found that students who reported playing more violent video games in junior and high school engaged in more aggressive behaviour," said Anderson, a psychologist. "We also found that amount of time spent playing video games in the past was associated with lower academic grades." In the second study, 210 college students played either a violent video game ("Wolfenstein 3D") or a non-violent video game ("Myst"). Afterwards, students were asked to punish an opponent with a noise blast. The study found that students who played the violent game tended to use longer bursts of noise. "The second study showed the causality between violent video games and aggression," said Dill, who started the groundwork for the study in 1994. Epic Games, creator of the top-selling -- and violent -- "Unreal Tournament," and games publisher Electronic Arts US, both refused comment. Electronic Arts' British office was also contacted and refused to comment. "There hasn't been a lot of study of violent video games prior to this," Dill said, adding that she was surprised that in the 28 years that video games have been around more studies had not been done. "I hope the exposure to studies like this may convince people to do more research." Roger Bennett, Director General of the European Leisure Software Publisher's Association (ELSPA) agrees that more research needs to be done, but questioned Anderson and Dill's work. "There seem to me to be an awful lot of experts these days. We are very keen to listen to any research that has a decent methodology, because I don't think a lot of these experts are looking at this sort of thing objectively." Bennett conceded he had not seen the report, but argued that the research had been conducted in America "which is a gun culture and very different to what goes on here." Dr Martin Barker of the University of Sussex, has been studying the relationship between behaviour and media exposure since 1980 and slammed the report as "non-sensical". He told ZDNet: "These results were so marginal they could not even support their own statistics." Barker believes studies like this, and a succession of earlier reports surrounding the Littleton massacre, need to study the craze that supports games like Doom and Unreal Tournament, rather than the short term effects of prolonged exposure to them. Asked if he allows his children to play violent video games he replies "yes, absolutely. Playing video games are not causative factors leading to violence. I have read hundreds of similar reports and upon closer inspection when they blame movies -- like Crash -- or video games like Doom, for violence they all fall apart. Unfortunately, the belief that games and film influences such behaviour is propagated by this sort of report." Do you believe video games lead to more aggressive behaviour? Tell the Mailroom