Research links TV violence to aggression — but not in girls

Preschool boys who watch violent television become markedly more aggressive and anti-social as they grow older, according to a study by Seattle researchers in one of the largest examinations so far of such connections.

At the same time, girls appear impervious to the effects of television violence, a finding that has the researchers puzzled.

The study, which focused on years of data for 330 children around the nation, found that each hour of violent shows viewed per day by boys ages 2 to 4 increased their aggression threefold, as reported by their parents five years later. It adds to a large body of evidence that kids learn from what they watch, the study's lead author said.

Parents kept track of which shows their kids watched and in the follow-up survey reported frequency of behavior including cheating, being mean, disobedience, being destructive, and showing a lack of remorse.

"Speaking broadly, the link between on-screen violence and subsequent violent behavior is as strong as evidence that smoking causes lung cancer," said Dr. Dimitri Christakis, a pediatric researcher with Seattle's Children's Hospital Research Institute and a professor at the University of Washington School of Medicine.

The paper was published today in the November issue of Pediatrics.

To arrive at their findings, the researchers established a definition of "violent" shows as those that revolved around fighting, fleeing or hostile language and threatening behavior. Those shows included some generally favored by girls as well as those usually watched by boys. Examples included "Power Rangers," "Space Jam" and even football for boys. For girls the examples included "Aladdin," "Pocahontas" and "Scooby-Doo."

"Parents have been socialized to think that cartoon violence is harmless, but it's not," Christakis said.

The fact that little girls weren't affected by the TV violence is something that should be studied more closely, Christakis said. For now, he attributes it to the possibility that boys are biologically more prone to aggression, along with differing social norms for girls' behavior. It's also unclear whether girls watch different amounts or types of violent shows than boys do, he said.

Educational or nonviolent entertainment did not significantly raise aggression levels in either sex.

The findings should inspire parents to limit the violent TV that their preschoolers watch, Christakis said. Earlier studies have shown that violent young kids tend to grow up to be violent adolescents and adults.

The latest study was observational, so it didn't establish that TV violence causes such subsequent behavioral problems. But researchers weeded out variables such as spanking to isolate TV's effects.

Christakis and his co-author, Frederick Zimmerman, were previously most widely known for a study that found that infants who watched educational baby videos such as "Brainy Baby" actually had smaller vocabularies than their peers who didn't. In the ensuing national furor, The Walt Disney Co., maker of "Baby Einstein" DVDs and other products, called the study misleading and unreliable and demanded that the UW retract a news release on it. The university refused.

Today's issue of Pediatrics also contains a paper by Christakis and Zimmerman that reports that each hour of violent television viewed by both boys and girls under 3 doubled their risk of attention problems five years later.

Even so, Christakis said his research isn't an indictment against television in general. He points out that other studies have found that high-quality programming can teach children lots of things. For example, shows like "Sesame Street" or "Dora the Explorer" can help preschoolers learn tolerance, sharing, counting and other skills.

"TV isn't inherently good or bad," Christakis said. "Content matters, and parents should be selective."

Kyung Song: 206-464-2423 or ksong@seattletimes.com