A unitary executive function predicts intelligence in children

Executive functions (EF) and intelligence are of critical importance to success in many everyday tasks. Working memory, or updating, which is one latent variable identified in confirmatory factor analytic models of executive functions, predicts intelligence (both fluid and crystallised) in adults, but inhibition and shifting do not (Friedman et al., 2006), suggesting that not all executive functions are related to intelligence. We aimed to test this hypothesis in a group of children where both intelligence and executive functioning are developing rapidly. The present study tested 215 children aged between 7 years 1 month and 9 years 11 months on measures of working memory, shifting, inhibition and intelligence (fluid and crystallised) to determine the associations between executive functions and intelligence in children of these age groups. A single factor model of executive functions provided the best fit to the data, and this factor was a strong predictor of both fluid and crystallised intelligence. While each construct (EF, fluid and crystallised intelligence) is dissociable in developing children, EF is essentially unitary and equally related to both kinds of intelligence.