A just-published article in Pediatrics looked at three studies – one in the US and two in Japan – which found that "playing violent videogames is a significant risk factor for later physically aggressive behavior and that this violent videogame effect on youth generalizes across very different cultures." The authors added that the research "strongly suggests reducing the exposure of youth to this risk factor." But context is important. The study's lead author Craig Anderson, a psychology professor at Iowa State University, told the Washington Post that the findings "should be understood in the larger context of a child's life." Playing 5-10 hours of a violent videogame isn't going to change a "healthy, normal, nonviolent child" into a violent one, Anderson said, adding that extreme aggression usually results from an array of "risk factors." The Post points out some such risk factors identified by the US surgeon general in 2001: "gang involvement, antisocial parents and peers, substance abuse, poverty and media violence." The study in Pediatrics reported that videogames are played in 90% of US homes with children 8-16 and "US average playing time of four hours a week in the late 1980s is now up to 13 hours a week, with boys averaging 16 to 18 hours a week," according to the Post. Here's coverage at Wired's geekdad blog and Health magazine. See also "US teens' gaming highly social."