Many studies have linked watching violence on television with aggressive behavior in youth, but new research shows that the impact continues into adulthood. Viewing violence on television appears to affect both boys and girls, but at different stages in life.
The American Academy of Pediatrics says a child who watches three to four hours of television each day will witness 8,000 dramatized murders throughout adolescence. It recommends that parents limit their children's TV viewing to one to two hours daily, in part because of the innumerable studies showing that youngsters who watch a lot of fictional violence are more prone to aggressive acts against others.
But a new study led by psychologist Jeffrey Johnson of New York's Columbia University suggests that the academy's guidelines may be too generous.
"At mean [average] age 14, we actually found that there was a big increase in the amount of aggression that took place if youths watched more than an hour per day," Mr. Johnson said.
The study, appearing in the journal Science, tracked 700 New York state children for 18 years from adolescence to adulthood. It divided them according to the amount of TV they viewed each day: less than one hour, one to three hours, and more than three hours. The researchers based their findings on interviews with their parents and on official government records. They found that those who watched more than one hour a day were more likely to get into fights, commit crimes or engage in other acts of aggression by the time they were in their late teens or early 20s.
"We also found that at mean age 22, the amount of time that young adults spend watching television is also associated with increased risk for committing the same kinds of acts over another eight-year follow-up period that ended at mean age 30," Mr. Johnson said.
While much research has already been done in this area, this study is novel because of its scope. Iowa State University psychologist Craig Anderson said the study is the first to show the lingering impact of TV violence.
"Prior research had not really focused that much on late adolescence and early adulthood TV viewing habits. So this study is unique in that it really does provide the first hard evidence that these effects are not restricted to childhood," Mr. Anderson said.
The link between television watching and violent behavior remained even after Jeffrey Johnson and his team statistically neutralized other factors that might be contributing factors, such as childhood neglect, poverty or psychiatric disorder.
"One of the most interesting things about our study is we split the sample in two and we found the same kind of effect in those individuals who had no prior history of engaging in aggressive behaviors before," he said. "The study also shows that girls are as likely to be impacted by TV violence as boys are, but not until early adulthood, possibly because they don't watch it as much as boys do during childhood," he said.
Craig Anderson says research shows that violent video games have the same impact on youth. He adds that the link between screen violence and aggressive behavior is not just a U.S. phenomenon, according to studies in Europe and other countries.
"This is a problem pretty much wherever there's a lot of violent entertainment media available. And as the Internet moves along and other electronic technologies advance throughout the world, it's a problem that's going to affect more areas as time goes on rather than fewer areas," Mr. Anderson said.
In the United States, political pressure forced commercial television networks to adopt a ratings system in 1997 that displays a content code on screens at the start of a program. It began by coding the amount of violence, then added ratings for offensive language, sex and other adult themes later that year.