Community Influences on Cognitive Ability

Although the environment determines important individual differences in cognitive ability, most home environment variables that correlate with children's intelligence are more strongly associated with the pleiotropic effects of genes than with causal pathways of environmental transmission. Here, we demonstrate that community variables, a hitherto understudied set of constructs in research on cognitive ability, are important variables for intellectual development in childhood. A model of highly multifactorial cultural transmission, in which many small effects of various aspects of the environment combine to influence the child, is assumed. Indexing these individual small effects with variables aggregated at the level of communities provides a magnifying lens for the detection of cultural transmission. Using census measures to test this model, we find several aspects of communities that show environmental relationships with child IQ over and above the genetic and environmental effects of parental IQ. The strongest association was found with characteristics of rural communities, which had a negative environmental influence on child IQ.