Aggressive tendencies fostered in children by violent television shows and video games can be tempered if they cut back their viewing and playing, a new Stanford University study shows.

Researchers found a decrease in the level of aggression at a San Jose elementary school after an effort to get pupils to watch less television. The effect was greatest for children who were already showing signs of hostility.

The study, being published in today's edition of the Archives of Pediatrics and Adolescent Medicine, is the latest in a string of studies linking violence with television and video games. But it is the first to show that those tendencies can be reversed.

"When kids reduced their exposure to videotapes, TV and video games, they become less aggressive," said Thomas N. Robinson, an assistant professor of medicine at Stanford and the study's lead author. "What this says is there is something you can do in a practical way, in a real-world setting, and see the effects."

Robinson also was author of a 1999 study based on the same research that found that children who cut down on television watching gained less weight than their peers.

Both studies relied on data gathered at two similar San Jose elementary schools, where researchers asked 192 third- and fourth-graders about aggressive classmates and made playground observations of both verbal and physical aggression. The researchers declined to identify the schools, citing promises of confidentiality.

43% Had TV in Rooms

Among their initial findings: 43 percent of the children in both schools had television sets in their rooms. Boys were seen being physically aggressive (punching, hitting, pushing, pulling or throwing objects) once every two minutes. For girls, it was once every five minutes.

After getting baseline measurements, the researchers introduced a curriculum at one school meant to encourage children to cut back on video games and to watch less TV.

Two-thirds of the pupils participated in an initial, 10-day effort to turn off television altogether, which was monitored by slips signed by parents. Just over half continued to limit their television watching to under seven hours per week at least once during the next 20 weeks.

When researchers went back, they found a 50 percent reduction in the level of verbal aggression seen on the playground at the experimental school compared with the one that did not follow the curriculum. They also noted 40 percent fewer instances of physical aggression, although that finding was not considered statistically significant.

Most Aggressive Improved More

Children who were the most aggressive at the outset of the study showed the greatest benefit.

"They have the most room to improve," Robinson said. "Our goal was to reduce aggression in the population as a whole. In doing that, it may have had a greater impact on those kids who tended to be more aggressive."

Besides the declines in aggression and obesity, Robinson said, there were anecdotal reports from teachers and parents of other benefits, including more effort spent on after-school projects.

"We had parents who said, 'This is the best thing that's happened to our family -- we talk to our kids at dinnertime now,' " he said. "One mother called and said her daughter used to sit at home and watch TV, and now she's found a friend down the block and they play outside every afternoon."

Dennis Wharton, a spokesman for the National Association of Broadcasters, said he had not seen the study and could not comment on it. But he said the industry believes that there is "conflicting evidence" on the link between television and real-world violence.

Industry Bucks Control of Content

The television and film industry has consistently fought government attempts to control the content of programming. Instead, Wharton said, they support ratings systems and technologies like the V-chip that allow parents to control what their children watch.

According to James Garbarino, a professor at Cornell University and author of "Lost Boys: Why Our Sons Turn Violent and How We Can Save Them," there is clearly a link between television violence and aggression in children. However, in an editorial he wrote accompanying the Stanford study, Garbarino said it probably accounts for only about 10 percent of children's aggression -- a link that is comparable to the one between smoking and cancer.

Other contributing factors, he said, include guns, child abuse, bad schools, inadequate mental health services -- even spiritual emptiness.

"Most people who smoke don't get cancer," Garbarino wrote. "Most kids who watch television do not act violently."

Robinson, who has two televisions in his own home, said he doesn't think television is "evil." But he does think the study shows that cutting back can have real benefits for children.

"Parents can set budgets in their households" for television viewing, he said. "That way they and their kids are watching what they really want to watch, rather than just whatever is on."

E-mail Ulysses Torassa at utorassa@sfchronicle.com.
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