Each hour of television four-year-olds watch on average a day increases their risk of becoming bullies in elementary school, according to a new U.S. study.
The research found that youngsters who spent a typical amount of time -- about 3½ hours daily -- in front of the tube had a 25 per cent increased risk of becoming bullies between the ages of 6 and 11.
"We see this very clear independent effect of television on children's bullying," said Frederick Zimmerman, lead author of the paper and a professor in the University of Washington's School of Public Health.
"More kids who watch a lot of TV go on to become bullies than kids who don't watch very much TV, so that's the risk. Watching a lot of TV doesn't mean that you're going to become a bully, it just means that you have a higher chance that it might happen."
Prof. Zimmerman said the study, which is published in the April issue of the Archives of Pediatrics & Adolescent Medicine, is unique in that it links television watching among young children with future bullying. It also concluded that good parenting reduced children's bullying.
However, Robert Thompson, director of the Centre for the Study of Popular Television at Syracuse University, said the tie between TV exposure and bullying is difficult to measure, and that any passive, isolationist behaviour that lasts for hours could also lead to aggressiveness among children.
"You've got to figure that what led them to that is a complex stew of their own genetics, their upbringing, the availability of free will -- not being monitored, having the opportunity to do things where somebody isn't there to make them stop. And then the culture that they grow up in," he said.
"I'm not saying that television has absolutely no impact, it's part of the recipe, but any study that tries to isolate it and show how does this ingredient in the recipe impact -- it's a very, very difficult thing to do."
But Prof. Zimmerman said youngsters are clearly soaking in TV violence. About 60 per cent of programs contain violence, according to the study.
"They're absorbing the message, they're absorbing the violent content, they're absorbing the fear," he said.
The findings come amid heightened concern over school bullying, which the study says affects an estimated 30 per cent of U.S. schoolchildren. Bullying is suspected in the death of 16-year-old Gary Hansen of Roblin, Man., who hanged himself last month.
The research is based on data on 641 four-year-olds drawn from the U.S. National Longitudinal Survey of Youth, which followed thousands of children from birth.
About 13 per cent of youngsters were identified as bullies by their mothers, who were asked whether their child "bullies or is cruel or mean to others." Bullying, which the study says must involve some kind of physical, social or psychologist power imbalance, wasn't defined. Prof. Zimmerman said independent behavioural observations would have been preferable, although the mother's measure "has been shown to be fairly reliable."
Parents were also asked how many hours their children spent watching television. The study did not ask about the content of the programs, which Prof. Zimmerman acknowledged rendered the results "incomplete." He said many four-year-olds watch educational shows and cartoons, some of which feature a high degree of violence.
The research also examined parenting in relation to bullying, and found that four-year-olds who received emotional support and cognitive stimulation are significantly less likely to become bullies. (Emotional support includes factors such as eating meals with both parents, talking to the children and frequency of spanking. Cognitive stimulation includes reading, playing and outings.)
The researchers accounted for the possibility that a child was already a bully at age 4, which could play a role in poor parenting and more television watching, and found it did not have a significant impact on results.