Tracing the development of executive function in the transition from infancy to early childhood: Relations between working memory, sustained attention, and inhibitory control

The first two years of life are characterized by tremendous cognitive and brain development, particularly in the domain of cognition known as executive function (EF). Two studies were conducted following the development of a group of children from 9 to 20 months. In the first study, 32 infants visited the lab at 9.5 months. This has been identified as a transition point in the development of EF as well as elicited imitation of multi-step sequences (EI). Infants completed assessments of inhibitory control (A-not-B and object retrieval), sustained attention, and immediate and deferred imitation. In a principal components analysis, A-not-B, sustained attention, and the clear- and opaque-box versions of the object retrieval task were relatively independent. Deferred imitation was related to performance on the object retrieval task using the opaque box only, which does not reflect inhibitory control. Immediate imitation was significantly correlated with object retrieval using both clear and opaque boxes, suggesting a role for inhibitory control in immediate but not deferred imitation.; Development of EF in the second year of life is less well understood. In the second study, 30 of the original 32 children returned to the lab at 15 and 20 months. They participated in the same set of EF tasks at each age: A-not-B with invisible displacement, Three Boxes, assessments of sustained attention, and elicited imitation-based measures of planning and inhibition. They also completed tests of immediate and deferred imitation. Children showed improvements in EF between 15 and 20 months on all tasks. Principal components analyses at each age revealed interesting patterns of relations between EF tasks. Correlations between EF at 15 and 20 months were for the most part statistically insignificant, with the exception of some of the elicited imitation-based measures. There were higher correlations between EF at 9 months and each of the two assessments in the second year of life, suggesting that there is in fact continuity in EF that may be related to continuity in the development of underlying neural structures.