Professor Linda Pagani of the University of Montreal and the CHU Sainte-Justine children's hospital said the American Academy of Pediatrics discourages watching television during infancy and recommends not more than 2 hours per day beyond age 2.
"This is the first time ever that a stringently controlled associational birth cohort study has looked at and found a relationship between too much toddler screen time and kindergarten risks for poor motor skills and psychosocial difficulties, like victimization by classmates," Pagani said in a statement.
"These findings suggest the need for better parental awareness and compliance with existing viewing recommendations put forth by the American Academy of Pediatrics. It seems that every extra hour has a remarkably negative influence."
About 1,000 girls and 1,000 boys in Quebec whose parents reported their television viewing behavior as part of the Quebec Longitudinal Study of Child Development.
Pagani noted the standard deviation is a commonly used statistic tool that indicates what is within a normal range compared to the average. One standard deviation from the average daily amount of television viewed by the toddlers in this sample of 105 minutes is 72 minutes.
The study, published in Pediatric Research, found some of the children who participated in the study were two or even three standard deviations away from the average of 105 minutes and their kindergarten indicators were correspondingly worse than those who were one standard deviation away.