Washington, Nov 25 (PTI): Parents, please note! Having a TV in the bedroom may affect your children's cognitive development, a new study has found.

Researchers from The Ohio State University found that preschoolers who have a TV in their bedroom and are exposed to more background TV have a weaker understanding of other people's beliefs and desires.

The team interviewed and tested 107 children and their parents to determine the relationship between preschoolers' television exposure and their understanding of mental states, such as beliefs, intentions, and feelings, known as theory of mind.

arents were asked to report how many hours of TV their children were exposed to, including background TV. The children were then given tasks based on theory of mind. These tasks assessed whether the children could acknowledge that others can have different beliefs and desires, that beliefs can be wrong, and that behaviours stem from beliefs.

The researchers found that having a bedroom TV and being exposed to more background TV was related to a weaker understanding of mental states, even after accounting for differences in performance based on age and the socioeconomic status of the parent.

However, preschoolers whose parents talked with them about TV performed better on theory of mind assessments.

Many studies have investigated the effects of children's TV exposure on social behaviours, without examining if TV exposure affects the neuropsychological function that underlies social behaviour, and without taking theory of mind into consideration.

This study shows that TV exposure may impair children's theory of mind development, and this impairment may be partly responsible for disruptive social behaviours, researchers said.

"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 said. The study was published in the Journal of Communication.