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PROBLEM: In the most recent issue of The Atlantic, Hanna Rosin channeled parents' fears over their young children's use of technology: Spend too much time with TVs and iPads, and a lovable toddler "could end up one of those sad, pale creatures who can't make eye contact and has an avatar for a girlfriend."

We're all pretty convinced, by now, that too much screen time is bad for children. But how much is too much? Is it just TV, or should we be threatened by video games, too? Is it worse if it's violent? Mindless? Does calling it educational make everything better?

METHODOLOGY: For guidance on these neurosis-inducing conundrums, researchers at the University of Glasgow turned to a representative sample of 11,000 U.K. children born at the dawn of the new millennium, and thus more or less guaranteed to have been raised in television's glow. Data on how much time kids spent watching TV and playing electronic games, as reported by their mothers, was collected when they were five.

The mothers also rated their childrens' psychological health and social ability on a ten-point scale; once when they were five, and again when they were seven. The researchers analyzed the kids' psychosocial adjustment in terms of how much screen time they had spent at age five. They accounted for as many alternative explanations as possible, from socioeconomic factors to carefully modeled intangibles like "family functioning" and "household chaos."