Our final set of results addresses heterogeneity in the effects of television on test scores. The effects on verbal, reading, and gen- eral knowledge scores are most positive for children from house- holds where English is not the primary language, for children whose mothers have less than a high school education, and for nonwhite children. When we combine student observables into a single index of parental investment—the time parents spent read- ing to their children in early childhood—we find that the effect of television is significantly more positive the lower is parental investment. Consistent with a rational-choice model, families in which television has relatively positive effects on learning also allocate more.
