March 28, 2002 -- Watching more than an hour a day of television can make adolescents more prone to violence as adults, according to a new study. Researchers say it's the first study to look at the long-term effects of TV viewing on aggressive behavior.
The study, published in the March 29 issue of the journal Science, tracked more than 700 children from adolescence to adulthood. Adolescents who watched an hour or more of television per day were more likely to engage in aggressive behavior directed against other people in their late teens and early 20s.
Researchers say that three to five violent acts are depicted in an average hour of prime-time television and 20 to 25 violent acts are shown in an average hour of children's programming. Previous studies have already linked viewing television violence to aggressive behavior in children, but little is known about the effect children's viewing habits have later in life.
"Our findings suggest that, at least during early adolescence, responsible parents should avoid permitting their children to watch more than one hour of television a day," says study author Jeffrey Johnson of Columbia University in a news release. "That's where the vast majority of the increase in risk occurs."
Johnson says that even after other factors that could contribute to violent behavior -- such as childhood neglect, low family income, or psychiatric disorders -- were accounted for, the link between watching TV and violence remained significant.
The study found less than 6% of the adolescents who watched less than an hour of television per day committed aggressive acts against other people in later years. But nearly 23% of those who watched between one and three hours a day committed violent acts, and that number grew to almost 29% among those who watched more than three hours.
Researchers say they also found an unexpected difference in sexes over time. The link between aggression and TV viewing habits was strongest for males during adolescence. But for females, the link was stronger during early adulthood. Common types of violent behaviors for boys included assault and fighting that resulted in injuries. For young women, robbery and threats to injure someone were most frequently reported.