Researchers observed 50 kids aged 1 to 3 at play in a room for an hour: half the time was television-free, and half the time the TV show "Jeopardy" was playing on a television in the room. Although the children in the room while the TV was on glanced up only occasionally, the researchers saw clear signs that the children had trouble concentrating.
"It's not something that you would really notice from just watching the child," says Daniel Anderson, a co-author of the study and a professor of psychology at the University of Massachusetts. "I really didn't know if children could just focus on their activity and shut out the background noise."
During the television-free time, Anderson and his colleagues observed standard psychological testing signs that the toddlers were focused and learning.
"The child gets an intent look on their face, they lean into the toy, their extraneous body movements decrease," Anderson says. "When they're in that state, they're much more likely to be learning."
But when "Jeopardy" came on, Anderson and his colleagues saw different behavior. The children played for half as long as they played without background television, and they were visibly less calm.
"You actually can see sometimes more aimless behavior, walking around like they're not quite sure what they're going to do next," Anderson says.
To Expose or Not to Expose?
The gulf is great between what pediatricians recommend for television watching and what children are exposed to in the home. According to a 2003 study from the Kaiser Family Foundation, two-thirds of children under 6 live in homes where the television is on half the time, and one-third of children live in homes where the television is left on "always" or "most of the time."
But the American Academy of Pediatrics recommends zero hours in front of the television for infants and toddlers under age 3. The average child under age 6 watches two hours a day. Even pediatricians aren't sure what this gap will mean for childhood development.
"The birthright for toddlers in 2008 is seemingly to be distracted," says Dr. Donald Schifrin, AAP spokesman on the impact of media on children. "By giving them the opportunity to be distracted we are conducting a rather uncontrolled experiment on our nation's children -- will our children grow up being distracted and distractible in their lifespan?"
Studying the Screens at Home
If on one end of the experiment are the millions of children parked in front of the television, the other end may be the few kids like 3-year-old Cassidy Kanner of Berkeley, Calif. Her parents watch zero television and neither do any of her preschool classmates, whose parents have all made an agreement with the preschool.
"She's never seen a television show in her life," says Cassidy's father, Allen Kanner, who works as a parent and a child psychologist. "It's not a problem: When she's left by herself, she takes out her blocks and starts to create a little fantasy world for herself."
"She has a very active imagination, which I think has a lot to do with not watching television," he says.
According to Dr. Dimitri Christakis, the George Adkins professor of pediatrics at the University of Washington and Seattle Children's Research Institute, Cassidy is doing a whole lot more than entertaining herself when she plays with blocks.
"Manipulating play helps language development," says Christakis. "When a child is playing with a truck, they are in fact, saying, 'Truck' internally."
In a term psychologists call "scaffolding," Cassidy might be silently talking to her toys in ways that help her understand language, Christakis says. Anderson says similarly focused, manipulating play helps toddlers develop skills to plan ahead intelligently, for example, to use a flat surface to help build or to put bigger blocks on the bottom.
"Those sorts of connections are happening beneath the surface, even though parents can't see them," says Christakis, who also wrote a book on the subject of household television called "The Elephant in the Living Room: Make Television Work for Your Kids."
At the moment, studies seem to show television at a young age interferes with learning.
"There have been a lot of studies that explored this, and early television is associated with delayed language, delayed cognitive developments, shorter attention span," Christakis says. "What we haven't found yet is the mechanism."
A Happy Medium?
Kanner says he chose a no-television household before Cassidy was born not as an experiment but as life for himself and his children. But for parents who don't want to abandon the television, experts say there's some control measures to take beyond counting hours.
"Try not to commingle play and television," says Schifrin. "Play is skill building -- physical, mental, emotional, behavioral skills. There is very little skill in watching television; we're all very good at that."
And finally, "Don't put a television in the bedroom," Schifrin says. "We're trying to create an amnesty program for bedroom televisions -- we'd like to go into every house and rescue these televisions from the kid's bedrooms."