Abstract

In our everyday lives, we are often confronted with having to do a number of different things at the same time. This makes doing any one thing much more difficult. This thesis examined how advancing age affects the ability to multitask (or task switch). It also examined how working memory affects age-related changes in task switching. To do this, both behavioural and electrophysiological brain responses were examined. It was found that compared to younger adults, older adults are slowed when responding in situations where a number of different tasks are presented in rapid succession. Consistent with our predictions, it was found that older adults with high working memory skills were preserved against this age-related change. This preserved ability (for older adults with high working memory) was accompanied by greater brain activity across prefrontal regions of the scalp (i.e., greater negative slow wave activity across left and right prefrontal leads). This is an important finding since the prefrontal cortex is deemed essential when actions have to be coordinated and planned. Greater prefrontal control was not found for younger adults, despite similarly fast reaction times. This suggests that older adults with high working memory recruit prefrontal control in order to compensate for the difficult task of switching between different response regimes. On the other hand, older adults with low working memory showed more posterior activity when preparing for a homogeneous target, suggesting that even when interference is absent, this group relied on external cues when preparing. Results are discussed in terms of recent task switching models.