Task switching performance in childhood and early adolescence: contribution of working memory and interference

Executive functions have a protracted course of development across childhood, adolescence, and into young adulthood. The present study adopts a ‘core component’ approach to studying the developmental progression of executive functioning with a specific focus on task switching performance. A number of theoretical models define working memory, inhibition, and task switching as core components of executive functioning, and show that these components are both independent and share common variance. This thesis details the creation of a new paradigm that allowed task switching performance, working memory span, and resistance to interference to be measured while holding constant task-specific factors such as stimulus- and response-demands. The main aim was to utilise this paradigm to examine how working memory and resistance to interference were associated with task switching performance, and more specifically, how these core components of executive functioning contribute to developmental change in task switching performance across childhood and early adolescence. A total of 33 young adults (aged 18-24 years) and 260 children (aged 4 years 6 months – 13 years 2 months) participated in the study. Task switching performance in adults was associated with working memory span and resistance to interference, but this relationship appeared to be specific to mixing cost measures only. Overall task switching performance improved with age. Path analysis was used to examine whether working memory and/or resistance to interference mediated the relationship between age and task switching RT at a trial specific level (i.e. all-repeat, mixed-repeat, or switch). Overall, both resistance to interference and working memory span mediated age-related change in task switching performance, but in quite different ways. Resistance to interference showed a generalised (non-specific) effect, mediating the effect of age on task switching performance for all trial types. In contrast, working memory span mediated performance under conditions that allowed advance preparation. The implications for these findings for theories of task switching are discussed.