The digital divide used to separate rich from poor; now it separates parents from their children. Whether it's infants watching the new 24-hour "Baby's First TV" channel, or teenagers instant messaging while they watch last night's "Daily Show" on their iPods, television is an enormous presence in the lives of kids today. The average American child spends three to five hours a day watching it. And they start their viewing careers much earlier than ever before: In 1961, the average child began to watch television at age 3; today it is 9 months.

Yet, for all the television kids are watching, much of what parents think they know about television's impact on their children is wrong. For instance, in the early 1970s, it was common knowledge that television was bad for your eyes: My own parents were convinced that my bad eyesight was the result of sitting too close to the screen, and they therefore made me stay at least six feet from it. Today, most people know that television viewing does not cause vision problems, but a host of new myths have emerged, still ripe for debunking:

1. TV makes kids dumb. Actually, high-quality TV shows such as "Sesame Street" and "Blue's Clues" improve children's cognitive abilities. Study after study has shown that children 3 to 5 years old who watch "Sesame Street" for an hour a day are better able to recognize numbers, letters and shapes than those who don't. When 500 kids who had participated in some of those studies were followed up as teenagers, those who had watched educational programs as preschoolers had higher grades, were reading more books, placed more value on achievement and were more creative than those who had not.

2. TV makes kids violent. The real story is more complicated. In 1994, researchers reviewed hundreds of studies involving thousands of children and concluded that there was clear evidence that watching violence on TV makes children more aggressive. Similarly, preteens and teenagers exposed to sexual content on television are more much more likely to engage in the kinds of activities they see on the screen.

But a study of more than 5,000 children also found that "pro-social" programs (think "Mr. Rogers' Neighborhood") make children kinder and more tolerant. In fact, the linkage between good behavior and watching good programming is as strong as the link between bad behavior and bad programming. The problem is that kids are increasingly watching shows with violence and sex instead of programming that is appropriate for their age.

3. Educational videos make infants smarter. The names — such as Baby Einstein and Brainy Baby — suggest one thing, but the data suggest otherwise. According to a 2005 report by the Kaiser Family Foundation, no program targeting children younger than 2 has demonstrated any educational benefit.