A new study shows that three-year-old kids who are exposed to more TV are at an increased risk for exhibiting aggressive behavior.

For the study, Jennifer A. Manganello, Ph.D., M.P.H., of University at Albany, State University of New York, Rensselaer, and Catherine A. Taylor, Ph.D., M.S.W., M.P.H., of Tulane University School of Public Health and Tropical Medicine, New Orleans, analyzed data from 3,128 mothers of children born from 1998 to 2000 in 20 large U.S. cities to examine associations of child television exposure and household television use with aggressive behavior in children.

Parents were interviewed at the time of the child's birth and at one and three years. At three years, they were asked to report time the child spent watching TV directly as well as household TV use on a typical day.

Aggression also was assessed at 3 years of age using a 15-item aggressive subscale for 2- and 3-year-old children. Demographic information and other risk factors for aggression were also noted.

About two-thirds (65 percent) of mothers reported that their 3-year-old child watched more than two hours of television per day. On average, children were exposed to an additional 5.2 hours of household TV use per day.