Children who watch more than two hours of television a day in early childhood are more likely to have attention problems as teens, a new study finds.

Researchers from the University of Otago in Dunedin, New Zealand, conducted a 14-year study observing more than 1,000 children from ages 3 through 15.

"Those who watched more than two hours, and particularly those who watched more than three hours, of television per day during childhood had above-average symptoms of attention problems in adolescence," Carl Landhuis of the University of Otago in Dunedin, wrote in his report, published in the journal Pediatrics.

For the study, researchers obtained parents’ estimates of their children’s television viewing time for ages 5, 7, 9 and 11.

Using various tools and questionnaires, the parents and the children themselves reported on attention problems at ages 13 and 15. For every additional 50 minutes of television watched on average per day, there was a measurable negative impact on attention, researchers said.

Those who watched the most TV earlier in childhood were more likely to have attention problems. In particular, those children who watched more than two hours per day had above-average symptoms of attention difficulties in adolescence, the study found.

Early childhood attention problems, socioeconomic status, gender or cognitive abilities did not influence the results, leading the researchers to conclude that watching too much TV was the most likely cause, according to a news release from the journal Pediatrics.

Possible explanations for the findings may be that the world portrayed on television makes real-life tasks seem boring in comparison, or that watching TV displaces the activities that encourage attention such as reading and playing games, the researchers said.