Ececutive Functions in Multi-tasking: Two, not four, evidenced in complex behaviours
Little 2011 MA.doc (510Kb)
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Traditional neuropsychological or ‘frontal’ tests often fail to reveal deficits of people exhibiting dysexecutive behaviours. Every-day multi-tasking is problematic and thought to relate to deficits in non-domain-specific executive functions (EFs). Miyake et al (2000), through systematic testing, developed a model of EFs: shifting, inhibition, updating and dual-tasking. Dual-tasking is reliably shown to be diminished in participants with every-day problems. This study aimed to show that dual-tasking was predictive of multi-tasking. Paper-and-pencil tests provided measures of EF and intelligence and multi-tasking ability was measured using the Edinburgh, Virtual Errands Test (EVET). Correlations between primary measures were non-significant except between ‘inhibition’ and ‘dual-tasking’. Contrary to hypothesis, dual-tasking was not found to be a significant predictor of multi-tasking. Exploratory analyses revealed relationships in component measures, particularly with an unadjusted measure of inhibition. The ‘supervisory system’ (Shallice & Burgess, 2006) was used as a framework to discuss findings, as well as research into activations in the anterior cingulate cortex (ACC) and dorsolateral prefrontal cortex (DLPFC) during inhibitory processing. The study concluded that EFs of ‘inhibition’ and ‘shifting’ were involved in the specification and later implementation of stimulus-response intentions but depend on interaction with monitoring processes in the ACC. ‘Updating’ was proposed to be representative of working memory and ‘dual-tasking’ was proposed to reflect successful strategy application to enable the monitoring of two independent behaviours without need of EF input. Deficits in dual-tasking are proposed to be a failure to impose the necessary monitoring criteria.