A new study from The Ohio State University reports that preschool-age children who are exposed to too much TV may have impaired cognitive development, which could be linked, at least partially, to disruptive social behaviors.

The researchers report that young children who have a TV in their bedroom or who are otherwise exposed to a lot of "background TV" have a weaker understanding of other people's beliefs and desires, which impairs their ability to build positive social relationships.

The Ohio State team tested 107 children and their parents to establish the relationship between the preschoolers' television exposure and their understanding of mental states such as beliefs, intentions and feelings. Collectively, the understanding of these mental states is know as theory of the mind.

Parents were asked to report how many hours of TV their preschoolers were exposed to each day, including background TV, in which the screen was on but was not necessarily the dominant object of the activity going on at moment, such as having the device on during a meal.

The researchers then tested the children on the theory of the mind by giving them tasks that tested whether the children could understand or acknowledge that others have different beliefs and desires, that beliefs can be wrong and that behaviors are a product of beliefs.

The preschoolers who had TVs in their bedrooms or who were exposed to lots of background TV did poorer on the tests assessing theory of the mind, even after the researchers factored in controls for age and socioeconomic status of the parents.

Interestingly, children whose parents talked with them about TV preformed better on the theory of the mind tests.

The researchers were led to believe that TV exposure may impair a child's theory of mind development, which can lead to disruptive social behaviors.

"When children achieve a theory of mind, they have reached a very important milestone in their social and cognitive development," said lead researcher Amy Nathanson. "Children with more developed theories of mind are better able to participate in social relationships. These children can engage in more sensitive, cooperative interactions with other children and are less likely to resort to aggression as a means of achieving goals."

Nathanson and her colleagues Molly Sharp, Fashina Aladé, Eric Rasmussen and Katheryn Christy, all of The Ohio State University, published their research in the Journal of Communication.