An intergrated analysis of the development of executive function: working memory, inhibition and shifting

Executive function is a higher-order cognitive ability that is important for goal directed behaviour, including the preparation, flexibility and execution of responses. Recent research (e.g., Miyake et al., 2000) suggests that executive function is comprised of three separate, but related components: working memory, response inhibition, and shifting. These components can be described as the ability to hold and manipulate information, inhibit or resist inappropriate behaviour or responses, and rapidly change between tasks or mindsets, respectively (Davidson, Amso, Anderson & Diamond, 2006). While the developmental trajectories of working memory, inhibition and shifting have been examined as individual constructs, there has been less research investigating all three together in child and adolescent populations. In addition, debate exists in the literature regarding when adult levels of performance are reached on task assessing executive function. The present research examined the development of working memory, inhibition and shifting using both a cross-sectional and longitudinal design. Two hundred and fifty eight children and adolescents, aged 5 to 14 years, and 33 adults participated in baseline testing. A smaller subtest of children, aged 6 to 10 years, were reassessed 12 months later. Developmental trends were mapped using an integrative paradigm where the base task, stimuli and response set remained consistent across the assessment of working memory, inhibition and shifting. The cross-sectional and longitudinal results presented in this thesis suggest that the three components of executive function have a long and protracted course of development. Working memory, inhibition and shifting all showed a similar pattern of more rapid development during middle childhood, which then slows during later childhood and adolescence. Overall, the results suggest that working memory, inhibition and shifting continue to develop into late adolescence or young adulthood. The findings are related to previous research and theory, and the wider implications for developmental research in executive function are explored.