The differentiation of executive functions in middle and late childhood: A longitudinal latent-variable analysis

Executive functions are cognitive processes that are associated with goal-directed behaviour. Although these functions are commonly thought to be related yet separable in young adults, attempts to replicate this finding in children have been mixed, as executive functions are indistinguishable in children up to 9 years of age but are related yet separable by 10-11 years. We aimed to provide longitudinal evidence of the differentiation of executive functions in this age range. The present study tested 135 children on a range of inhibition, working memory, and shifting measures twice over a two year period (mean age = 8 years 3 months and 10 years 3 months) to determine if any changes in the structure of executive function occur in this age range. Longitudinal factor analyses showed that the structure of executive functions significantly differed between testing periods, and that the factor structure of executive functions changed from a one-factor (i.e. unitary) model to a two-factor model where working memory was separable yet related to an inhibition/shifting factor. Further structural equation models showed that the unitary factor from testing period 1 was highly, but not entirely, predictive of the two factors yielded from testing period 2. The results provide evidence for the development and differentiation of executive functions, and the distinction between general and specific executive abilities. (C) 2014 Elsevier Inc. All rights reserved.