Three scientific studies published Monday found what parents already tell their kids: It's better to stare at the PC screen instead of the TV.

The articles in "Archives of Pediatrics & Adolescent Medicine" correlated the amount of television young children watched with test scores and achievement as grown-ups.

In one study, Robert Hancox, Barry Milne and Richie Poulton, researchers at the Dunedin School of Medicine, studied 1,000 New Zealanders, most of whom were 26 years old.

They found that the more time the research subjects had spent watching TV during childhood, the more likely they were not to have made it through college. TV watching as a teen and especially during adolescence made it more likely they were to have left school without a sixth-form certificate, the degree needed to go on to university.

The findings held true regardless of sex, intelligence or socio-economic status, the researchers found. They posit that there's a simple trade-off between watching television and doing homework -- with no intellectual benefits to the tube.

"These findings offer little support for the hypothesis that a small amount of television is beneficial, whereas a lot is harmful," they wrote in the "Archives of Pediatrics & Adolescent Medicine."

A second study by Dina Borzekowski of the Johns Hopkins Bloomberg School of Public Health and Thomas Robinson of Stanford Department of Pediatrics and Stanford Prevention Research Center found that media influence children's development. But the study failed to determine associations between the child's household media use and academic achievement.

Borzekowski and Robinson surveyed grade-schoolers in six diverse California schools over the course of a year. They found that kids who had a TV in their bedrooms had significantly lower test scores than those who didn't. Kids without a bedroom boob tube and did have access to a home computer had the highest test scores.

Finally, Frederick Zimmerman and Dimitri Christakis of the University of Washington analyzed data on kids' TV habits in order to study the effect of watching TV and reading skills development. They looked at scores on three reading and comprehension tests.

Children under three watched an average of 2.2 hours per day; at ages 3 to 5 years, the daily average was 3.3 hours. The under-three couch potatoes had lower scores on all three tests.

However, kids in the three-to-five age group showed a 0.51 percent improvement in the reading recognition test for every hour they watched.

Zimmerman and Christakis concluded that watching TV could stunt the thinking of children under three. They advised parents to follow the American Academy of Pediatrics guidelines and not let kids under two watch TV at all.