The study, conducted by researchers at the University of Washington, found that, for every hour per day that children under 3 watched shows like "Power Rangers" their risk for attention problems five years later doubled.
Other non-violent, but fast-paced cartoons like "Rugrats" and "The Flintstones" also posed a significant increase in risk of attention problems.
On the other hand, educational shows, including "Arthur", "Barney" and "Sesame Street", had no association with future attention problems.
Interestingly, the risks only occurred in children younger than age 3, perhaps because that is a particularly crucial period of brain development. Those results echo another recent study that suggested that TV watching has less impact on older children's behaviour than on toddlers.
The study included a nationally representative sample of 967 children whose parents answered government funded questionnaires in 1997 and 2002. In 1997 parents were asked questions about their child's television viewing habits. Then, in 2002, they were asked about their children's behaviour, including things such as inattentiveness, difficulty concentrating and restlessness.
Researchers took into account other factors that could have skewed results (including cultural differences, parents' educational levels, etc.), and still found a strong link between non-educational shows and future attention problems.
Previous research and news reports on TV's effects have tended to view television as a single entity, without regard to content. But "the reality is that it's not inherently good or bad. It really depends on what they watch," said Dr. Dimitri Christakis, who co-authored the study with researcher Frederick Zimmerman.