United States and thus warrant explicit discussion. Children spend more time watching television than in any other single activity except sleep (Huston and Wright, 1997). Children between the ages of 2 and 17 spend an average of 4.5 hours a day in front of screens, watching television, playing video games, and using the computer (Woodard and Gridina, 2000). The potentially adverse consequences of television viewing led the American Academy of Pediatrics to recommend that children under 2 years old should not watch television, and older children should not have television sets in their bedrooms (American Academy of Pediatrics, 1999b).
Violent Media Content and Aggressive Behavior. The association between viewing violent television programs and aggression has been well established (Bushman and Huesmann, 2001; Friedrich-Cofer and Huston, 1986; Huesmann and Eron, 1986). Across methodologies (laboratory experiments, field studies, and longitudinal studies) and measures, research has converged on findings that viewing television violence affects both short-term and long-term aggressive behavior (Friedrich-Cofer and Huston, 1986). A comprehensive meta-analysis of 217 studies of the association between antisocial behavior and media violence revealed the correlation between the two to be sizable: .31 (Paik and Comstock, 1994), a correlation only slightly smaller than that between smoking and lung cancer (Bushman and Anderson, 2001).
Because of the interactive nature of video games, both researchers and the public are particularly concerned about the effects on children of violent content in such games (Calvert and Tan, 1994). As with television, research has converged to suggest that playing violent video games contributes to aggressive behavior (Anderson and Bushman, 2001; Bensley and Van Eenwyk, 2001; Sherry, 2001), but in this case the research is mainly drawn from smaller (i.e., Ns of 50 to 150), largely white and middle-class convenience samples.
Media Use and Obesity. Not all empirical studies have established a positive association between television or video game use (or both) and increased weight or obesity in youth. The most widely cited study is by Dietz and Gortmaker (1985), who report that the prevalence of obesity in a large epidemiological sample of adolescents ages 12–17 increased 2 percent for each additional hour of television watched per week. Subsequent studies have confirmed this relationship (Dietz and Gortmaker, 1985; Robinson and Killen, 1995; Robinson et al., 1993; McMurray et al., 2000; Durant et al., 1994).
One way in which television viewing or video game use is thought to be related to increased weight in children is that time spent with these media displaces physical activity. Evidence for the displacement of physical activity by television is mixed, with some studies documenting decreases in participation in physical activities following the introduction of television into small, mainly rural, communities (Brown et al., 1974; Williams, 1986), but more representative