Children and teenagers who play violent video games show increased physical aggression months afterward, according to new research that adds another layer of evidence to the continuing debate over the video-game habits of the youngest generation.
The research, published today in the journal Pediatrics, brings together three longitudinal studies, one from the United States and two from Japan, examining the content of games, how often they are played and aggressive behaviors later in a school year.
The U.S. research was the first in the nation to look at the effects of violent video games over time, said lead author Craig A. Anderson, a psychology professor at Iowa State University and director of its Center for the Study of Violence.
Anderson said the collaboration with Japanese researchers was particularly telling because video games are popular there and crime and aggression are less prevalent. Some gamers have cited Japan's example as evidence that violent games are not harmful.
Yet the studies produced similar findings in both countries, Anderson said. "When you find consistent effects across two very different cultures, you're looking at a pretty powerful phenomenon," he said. "One can no longer claim this is somehow a uniquely American phenomenon. This is a general phenomenon that occurs across cultures."
The study in the United States showed an increased likelihood of getting into a fight at school or being identified by a teacher or peer as being physically aggressive five to six months later in the same school year. It focused on 364 children ages 9 to 12 in Minnesota and was first included in a 2007 book, "Violent Video Game Effects on Children and Adolescents."
Japanese researchers studied more than 1,200 Japanese youths ages 12 to 18. In all three studies, researchers accounted for gender and previous aggressiveness.
"We now have conclusive evidence that playing violent video games has harmful effects on children and adolescents," Anderson said.
The American Academy of Pediatrics, which publishes the journal in which the study appears this month, is in the process of revising its recommendations on media violence, and expects to issue a new statement in four to six months, a spokeswoman said. The academy now recognizes violence in media as a significant health risk to children and adolescents and recommends limiting screen time including television, computers and video games to one to two hours a day.
For many parents, the latest research was unsettling, though not surprising.
Patricia Daumas, 50, a single mother of two in Reston, said she sometimes wonders about her decision to allow her sons, ages 8 and 11, to play war games. But like many parents, she sees the issue as complex. She does not allow her sons to play games rated "mature."
"I don't think the games are good for them," she said, "but what I'm seeing in my own children is that they're still very gentle, that they're very caring, and they have absolutely no behavior problems at school."
Daumas noted that many of her sons' friends play the games. "It's a tough balancing act," she said.
Tracey Goldman, 42, a mother of two in Takoma Park, said she enforces time limits on video-game playing and does not allow violent content. Her fourth-grader plays Lego Star Wars, she said, but otherwise, "I just feel very uneasy about letting him play those kinds of games."
Still, she said, monitoring game-time can require vigilance because children can find games on Internet sites. She recalled looking over her son's shoulder as he played at a computer, asking: "Wait a minute. Is that shooting people?"
Parents have debated the potentially harmful effects of video-game violence for most of the last two decades, as the games have become more popular and more graphic. In the new research, games were deemed violent when one character harmed or killed another.
Still, not all video games are violent or associated with such negative effects, said Joseph Kahne of Mills College in Oakland, Calif., coauthor of a recent video-gaming study by the Pew Internet & American Life Project.
The Pew study, based on a poll of 1,102 youths ages 12 to 17, found that most teenagers play many different kinds of games and that some types of play -- such as making decisions about how to run a city -- are correlated with more political or civic involvement.
Overall, Kahne said, "it's important to pay attention to the nature of the games and the sense that kids make of the experience."
Although the longitudinal studies reported in Anderson's study showed that frequent playing of violent video games leads to greater aggression, Anderson also said this message should be understood in the larger context of a child's life.
"A healthy, normal, nonviolent child or adolescent who has no other risk factors for high aggression or violence is not going to become a school shooter simply because they play five hours or 10 hours a week of these violent video games," he said.
Extreme forms of violence, Anderson said, "almost always occur when there is a convergence of multiple risk factors."
A U.S. surgeon general report in 2001 identified an array of those risk factors, including gang involvement, antisocial parents and peers, substance abuse, poverty and media violence. Males are more at risk.
The new study noted that video games are played in 90 percent of American homes with children ages 8 to 16 and that the U.S. 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.
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