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More Than One Hour of TV a Day May Lead to Violence Among Teens
Watching more than one hour of television per day may make adolescents more prone to violence in adulthood, according to new research. The study, appearing in Science, is believed to be the first to investigate the long-term effects of television viewing on aggressive behavior.
Jeffrey Johnson of Columbia University and the New York State Psychiatric Institute and his co-authors tracked more than 700 children from adolescence to adulthood. Adolescents who watched one hour or more of television per day were more likely in their late teens and early twenties to engage in aggressive acts against other people, researchers found. This was especially true for boys.
Young adults--especially women--who watched two or more hours of television per day were also more prone to violence.
“Our findings suggest that, at least during early adolescence, responsible parents should avoid permitting their children watch more than one hour of television a day,” Johnson said. “That’s where the vast majority of the increase in risk occurs.”
The link between watching television and behaving violently remained intact after the researchers had accounted for other factors that might be responsible for television viewing and violent behavior, such as childhood neglect, low family income, or a psychiatric disorder during adolescence.
The youths in the study and their mothers were interviewed four times over the course of 18 years and assigned to three categories: those who watched less than one hour of television per day, between one and three hours per day, and more than three hours per day.
Three to five violent acts occur in an average hour of prime-time television, and 20 to 25 violent acts occur in an average hour of children’s television, according to Johnson. Thus, the amount of television the study subjects watched per day should generally reflect the amount of violence they saw, he reasoned.
Information on aggressive acts committed by the study subjects came from interviews, as well as state and federal records of arrests and charges for adult criminal behavior. The researchers grouped the violent acts according to whether they occurred around age 16, age 22, or age 30.
The Science study thus contradicts a common assumption that media violence only affects children, say Craig Anderson and Brad Bushman of Iowa State University of Science and Technology, in a related commentary.
An unexpected gender difference emerged as the study progressed, with the link between aggression and television watching being strongest for males during adolescence, and for females, during early adulthood. While the most common types of violent behavior for boys were assault and fighting that led to injuries, violent behavior by young women also included robbery and threats to injure someone. “It’s quite surprising. We certainly wouldn’t have predicted what we found,” Johnson said.
The age difference might reflect the fact that adolescent girls watch less violent television programs, Johnson said. He cautioned that this hypothesis needs further investigation, however, because television programming has changed significantly since television viewing by the adolescent girls was last assessed in 1983.
Johnson and his colleagues addressed the “chicken and egg” question: Does television watching cause aggression? Or, do people prone to aggression watch more television?
The researchers investigated whether individuals with a history of aggressive behavior were more likely to watch large amounts of television when they were a few years older. In fact, the authors found that was not generally the case, suggesting that heavy television watching leads to aggression, instead of vice versa.
Another task of the study was to determine how much of the apparent link between television viewing and aggressive behavior was in fact caused by watching television. The authors identified six other kinds of adversities that were most common among the study subjects who watched large amounts of television and committed violent acts.
Johnson’s group then analyzed rates of violence among those who had experienced each of the other factors, such as growing up in an unsafe neighborhood, and those who hadn’t. If the rates were the same in both groups, it indicated that the experience in question didn’t contribute to aggressive behavior. When the rates were different, the authors used a computer statistics program to sort out how much of the aggressive behavior could be attributed to television watching alone.
Once other factors were accounted for, 5.7 percent of the adolescents who watched less than one hour then committed aggressive acts against other people in later years. In contrast, 22.5 percent of the adolescents who watched between one and three hours a day committed aggressive acts later, as did 28.8 percent of the adolescents who watched more than three hours a day.
Johnson emphasized that violent behavior was just one of several unwanted effects of watching large amounts of television.
“The increased rate of television viewing appears to be related to an increased prevalence of obesity in the general population,” he said. “Researchers have found a wide variety of negative outcomes that are associated with extensive television viewing.”