Abstract
Physical action and cognition are often entangled as one directs their oculomotor system to events deemed important. Particularly, incorporating mental representations and processes with eye movement relies on working memory. In an attempt to understand the impact of effortful physical action on cognition that extends beyond the oculomotor system, we have previously demonstrated that increased physical load impairs cognitive control and its manifestation in visual attention and working memory (Marcus et al., 2016, VSS). Given the growing literature indicating the decline in executive functions with aging, it is thus important to further examine whether older age magnifies the detrimental effects of physical load on cognitive control. In the present study, 16 older and 16 younger adults participated in a working memory color Change Detection task under a concurrent physical load. Physical load was operationalized as different levels (5% versus 30%) of the maximal voluntary contraction exerted on an isometric dynamometer by individual participants. For both groups, working memory performance was comparable between the two physical load conditions. However, working memory performance decreased from low physical load to high physical load when five irrelevant colors were presented along with the to-be-remembered colors, suggesting reduced cognitive control of access to working memory under high physical load. Moreover, this reduction was greater in older participants than younger participants. Together these results suggest that age modulates the interactions between physical and cognitive efforts.