Television viewing before the age of three may have adverse effects on subsequent cognitive development, according to a study in the July issue of Archives of Pediatrics & Adolescent Medicine, one of the JAMA/Archives journals.

Three- to five-year-old children watch an average of two or more hours of television or videos per day and much of this is not children's educational programming, according to background information in the article. Fifty-nine percent of children younger than two years regularly watch an average of 1.3 hours of television per day, despite the fact that there is no programming of proven educational value for children this young. A substantial portion of television actually watched by children does not meet the American Academy of Pediatrics recommendation of no screen time for children younger than two and only high quality, age-appropriate viewing thereafter, the authors suggest.

Frederick J. Zimmerman, Ph.D., and Dimitri A Christakis, M.D., M.P.H., of the University of Washington, Seattle, analyzed data from The National Longitudinal Survey of Youth 1979 Children and Young Adults (NLSY-Child), begun in 1986 and conducted every other year. The NLSY-Child collects information on more than 11,000 children regarding developmental assessment, family background, home environment and health history. The researchers assessed data on 1,797 children who were approximately six years of age at the time of one of the four most recent survey interviews in 1994, 1996, 1998 and 2000. Scores in mathematics, reading recognition and reading comprehension from a commonly used and well-standardized test were compared with the level of television watching before age three and from ages three to five.

"This analysis has shown a consistent pattern of negative associations between television viewing before age three years and adverse cognitive outcomes at ages six and seven years," the authors report. "The inclusion of extensive controls for parental preferences, ability, and investment in their children's cognitive development suggests that these associations may in some direct or indirect way be causal."

"By contrast, this analysis suggests that television viewing at ages three to five years has a more beneficial effect, at least for the outcomes of reading recognition and short-term memory," the authors write. The researchers found no beneficial effect on mathematics outcomes or reading comprehension, and they state, "Because reading recognition and short-term memory are arguably the most basic of the cognitive outcomes studied, the implication would seem to be that the net effect of television viewing from a population perspective is limited in its beneficial impact."

"One of the contributions of this study is to recognize and explicitly model the heterogeneous [mixed] effect of television viewing at different ages on children's outcomes," the authors write. "Television viewing in early childhood varies depending on age; for very young children the effects are negative, while for preschool children they can be constructive, at least in some domains. This analysis further suggests that parents may appreciate and benefit from better guidance on the kinds of high-quality content that is available on television and on ways of managing the context of television viewing to maximize its potential benefit for their children."

JAMA and Archives Journals