Research Is Rare
Research studies of very young children and television are uncommon. As Dr. Shifrin notes, "There's not a lot of research on the horizon. Who's going to submit a six-month-old for a television study?"
The Henry J. Kaiser Family Foundation has looked extensively at the influence of media on children's lives, and its researchers lament the lack of information on this topic. "To date there is remarkably little data regarding how learning-oriented electronic media products are used in the daily lives of young children, let alone whether they have a positive, negative, or neutral effect on their young users," according to A Teacher in the Living Room: Educational Media for Babies, Toddlers, and Preschoolers, a December 2005 report from the Foundation.
The studies that have been done generally rely on parent reporting of the number of hours watched and often are "retrospective studies," in which researchers look back at viewing habits and try to correlate them with children's current attitudes, says Dr. Passer.
In one of the most-cited studies, Dr. Dimitri Christakis of the University of Washington and his three co-authors asked parents how much television their children watched at ages one and three. When the children were seven years old, the doctors evaluated their abilities to focus their attention.
Dr. Christakis found that a greater number of hours of TV watched at ages one and three corresponded with "an increase in the probability of having attention problems at age seven," according to the article "Early Television Exposure and Subsequent Attentional Problems in Children," which appeared in the April 2004 edition of Pediatrics.
Another study by Dr. Frederick Zimmerman and Dr. Christakis linked each hour of daily TV before age three to lower performance on reading comprehension and short-term memory tests at ages six and seven. The study, "Children's Television Viewing and Cognitive Outcomes," appeared in the Journal of Pediatrics and Adolescent Medicine in July 2005. Drs. Christakis and Zimmerman are also co-authors of the new book The Elephant in the Living Room: Make Television Work for Your Kids.
All experts consulted for this article agree that much more research needs to be done. A lot of the existing research questions whether children under age two really comprehend what happens on TV or are just "entertained" by it, wrote Dr. Robin Close the United Kingdom's National Literacy Trust in a 2004 report.
And "child development experts argue that we need a much better understanding of media's impact on brain development, future media use, and displacement of other activities," according to the Kaiser report—for instance, whether more TV means less social interaction.