PRESCHOOL TELEVISION VIEWING AND ADOLESCENT TEST SCORES: HISTORICAL EVIDENCE FROM THE COLEMAN STUDY
MATTHEW GENTZKOW AND JESSE M. SHAPIRO
We use heterogeneity in the timing of television’s introduction to different local markets to identify the effect of preschool television exposure on standardized test scores during adolescence. Our preferred point estimate indicates that an additional year of preschool television exposure raises average adolescent test scores by about 0.02 standard deviations. We are able to reject negative effects larger than about 0.03 standard deviations per year of television exposure. For reading and general knowledge scores, the positive effects we find are marginally statistically significant, and these effects are largest for children from households where English is not the primary language, for children whose mothers have less than a high school education, and for nonwhite children.
I. INTRODUCTION Television has attracted young viewers since broadcasting be- gan in the 1940s. Concerns about its effects on the cognitive devel- opment of young children emerged almost immediately and have been fueled by academic research showing a negative association between early-childhood television viewing and later academic achievement.1 These findings have contributed to a belief among the vast majority of pediatricians that television has “negative effects on brain development” of children below age five (Gentile et al. 2004). They have also provided partial motivation for re- cent recommendations that preschool children’s television view- ing time be severely restricted (American Academy of Pediatrics 2001). According to a widely cited report on media use by young
* We are grateful to Dominic Brewer, John Collins, Ronald Ehrenberg, Eric Hanushek, and Mary Morris (at ICPSR) for assistance with Coleman study data, and to Christopher Berry for supplying data on school quality. Lisa Furchtgott, Jennifer Paniza, and Mike Sinkinson provided outstanding research assistance. We thank Marianne Bertrand, Stefano DellaVigna, Ed Glaeser, Austan Gools- bee, Jim Heckman, Caroline Hoxby, Larry Katz, Steve Levitt, Ethan Lieber, Jens Ludwig, Kevin M. Murphy, Emily Oster, Matthew Rabin, Andrei Shleifer, Chad Syverson, Bob Topel, workshop participants at the University of Chicago, Harvard University, UC Berkeley, the NBER, the University of Notre Dame, and the APPAM, and four anonymous referees for helpful comments. e-mail: [email protected], [email protected]. 1. Recent studies showing negative correlations between early childhood viewing and later performance include Christakis et al. (2004), Hancox, Milne, and Poulton (2005) and Zimmerman and Christakis (2005). An older literature finds more mixed results, but reviewers conclude that the overall thrust of the evidence points toward negative effects of television (Strasburger 1986; Beentjes and Van der Voort 1988; Van Evra 1998).