Investigators Dimitri A Christakis, MD, MPH, and Frederick Zimmerman, PhD, both of Seattle Children's Hospital Research Institute and the University of Washington School of Medicine, add these findings to their growing body of research on the effects of television and media on children and their ability to learn, socialize and develop.

The journal article titled Violent Television Viewing During Preschool is Associated with Anti-social Behavior During School Age reviews data from the Panel Study of Income Dynamics, which is a 40-year study of 8,000
US families.

The project looked at the types of programming watched by 184 boys and 146 girls between ages two and five, and anti-social behaviours between ages seven and 10.

A clear link was found between pre-school age boys who watched violent programs and their later development of anti-social and aggressive behaviours at ages seven to nine. There was no such correlation found for girls.

Christakis says, "This new study provides further evidence of how important and powerful television and media are as young children develop. However, the news here is not all bad. While we found that shows like violent cartoons or football can make children more aggressive, we found no such effect for other programmes such as educational ones.

"This points out that parents must be informed and very selective when making media choices for their children. These findings are a bit unnerving because we know from other studies that the behaviors children manifest in early childhood track into adolescence and even into adulthood.

"As children grow older they gradually learn coping skills to deal with difficult situations, so it's important to provide positive role models for them at a young age."

In the study, television programming such as football, many cartoons and titles like Power Rangers, Star Wars, Space Jam and Spider Man were all classed as violent entertainment because characters fight or flee from
violent situations, laugh or cheer as they rejoice in violent acts, and show more violence than would be expected in the everyday life of a child.

Even G-rated films intended for children can be filled with violence and classed as violent entertainment, according to this definition. By contrast, shows considered non-violent included programmes like Toy Story, Flintstones and Rugrats.

A third category of educational programming was also reviewed, such as Barney, Sesame Street, Magic School Bus and Winnie-the-Pooh.

Significantly, the correlation to later aggressive and anti-social behaviors in boys only appeared with those shows and programming rated as violent.

It has long been suspected that television, media and entertainment have a great impact on the development of children.

Christakis adds, "We now recognise that content is key. Given the media saturated world that young children now inhabit, we need further research and policies to ensure that media exerts a positive influence on children."

In a related companion journal article appearing in the same issue of Pediatrics called Association Between Content Types of Early Media Exposure and Subsequent Attentional Problems, the same researchers found that for children under age three, each hour per day spent watching violent television was associated with approximately twice the risk of attention problems five years later.