Discussion (summarized by C.M. Super)

The discussion focused primarily on the unusually strong correlations between motor development in infancy on the one hand, and intellectual ability and educational achievements in childhood and adolescence on the other, and how they might be interpreted. Pollitt suggested that, pending further analysis, it was not possible to distinguish between two possibilities: (1) that motor development served as a marker for powerful covariates, such as family factors, which influenced the outcomes in late adolescence noted here, and (2) that nutrition had a common influence on both infant motor development and later cognitive attainments. A link between nutrition and motor development was found at 15 months, but possible covariates have not yet been explored. It was suggested that motor scores in infancy might reflect an ability to interact with the environment, but this would be different from the pattern typically reported in U.S. and Canadian studies. Pollitt emphasized that these results could not be predicted from findings in well-nourished populations, nor should they be generalized to them. It was commented that this is a good example of how longitudinal correlations tell us as much about a child's environment as they do about the child's development per se.