Changing the channel on what TV children watch could improve their behaviour, but watching too much regular programming may have harmful long-term consequences, new research suggests.

In Monday's issue of the journal Pediatrics, researchers reported that preschoolers spent less time watching violent programming when they were randomly assigned to participate in a program that encouraged aggression-filled shows to be replaced with educational or empathy-building viewing compared with a control group.

Muppets Bert, left, and Ernie, from the children's program Sesame Street, were created to teach preschoolers that people can be good friends with those who are very different from themselves, which builds empathy. (Beth A. Keiser/Associated Press)

"We demonstrated that an intervention to modify the viewing habits of preschool-aged children can significantly enhance their overall social and emotional competence and that low-income boys may derive the greatest benefit," Dr. Dimitri Christakis of Seattle Children's Research Institute and his co-authors concluded.

"Although television is frequently implicated as a cause of many problems in children, our research indicates that it may also be part of the solution."

There was no difference in total viewing time between the 820 families involved in the study.

The educational or "prosocial" programs included Sesame Street, Dora the Explorer and Super Why. A second category of shows also promoted co-operative problem-solving and non-violent conflict resolution — but inconsistently, as on Mickey Mouse Clubhouse, for example.

Programs included in the media diaries were coded for ratings, content and pacing, such as fantasy violence or gratuitous violence.

Parents were also encouraged to watch with their children.

Offer more nuanced message

At six months, the children in the intervention group demonstrated significantly less aggression and more positive behaviour compared to the control group, and the effect lasted for 12 months.

The American Academy of Pediatrics recommends that children watch TV one to two hours or less a day but surveys show the message isn't getting through, particularly as screens become a bigger part of our lives, said Dr. Claire McCarthy, a pediatrician at Boston Children's Hospital.

Instead of repeating the simple message of turning the TV off, McCarthy argues in a journal commentary accompanying the research that it's time to take the more nuanced approach in the study: educate parents and children about how watching violent programming can cause aggressive behaviour and give practical ways to shift their viewing.

McCarthy suggests that parents:

• Get informed.
• Watch what their children and teens are viewing in all forms — TV, video, games and online — and talk about it together in a nonjudgmental way.
• Teach media literacy starting at a young age and check that what children are viewing is age-appropriate, including what's on in the background.

Doctors can also play a role through outreach with the entertainment industry, said McCarthy, who is also a professor of pediatrics at Harvard Medical School.

Another study in the same issue looked at TV viewing among children and teens in New Zealand who were followed into adulthood.

Young adults who'd spent more time watching TV were likely to have a non-violent criminal conviction, diagnosis of antisocial personality disorder and aggressive personality traits in early adulthood, Dr. Robert Hancox of the University of Otago and his team found.

"To our knowledge, this is the first longitudinal study to demonstrate long-term associations between television viewing and a broad range of antisocial behaviour," they said.

While the study can't prove that watching TV causes antisocial behaviour, the long-term study adds to the evidence suggesting it could be a factor, said Caroline Fitzpatrick, a postdoctoral researcher at New York University who has studied how early TV viewing influences development in Quebec.

Christakis and Hancox's research was funded by the U.S. National Institutes of Health and New Zealand Health Research Council.