UC Riverside

Physical action and cognition are often entangled in our daily lives. To understand the impact of effortful physical action on cognition, the work presented in this dissertation used a simple, yet effortful, physical action (i.e., effortful handgrip exertion) during cognitive tasks to investigate 1) the effect of a simultaneous effortful physical and cognitive action on inhibitory control and 2) arousal induced by physical exertion. Physical exertion was operationalized as different levels (low versus high) of the maximal voluntary contraction (MVC) exerted on an isometric hand dynamometer, which is an apparatus that measures participants’ maximum isometric handgrip strength and involves static contraction of the hand muscles with restricted joint movements. Across different task paradigms, effortful physical exertion impaired observers’ ability to ignore distractors, or task-irrelevant items, and successfully recall/detect task-relevant items. While physical and cognitive effort often interact with one another, they can even exhibit similar behavioral and neural effects. For instance, pupillary response, such as pupil dilation, typically increases with cognitive or physical effort, indicating increased arousal and Locus Coeruleus-Norepinephrine (LC-NE) activity. Given that pupillary response is a proxy for LC-NE activity, the work in the present dissertation also aimed to examine the impact of engaging in a concurrent effortful physical and cognitive task on task evoked pupil responses (TEPR). Replicating prior work, effortful physical exertion induced greater pupillary response in comparison to lower physical exertion. However, high cognitive load and the interaction between physical exertion and cognitive load was not significant. The finding that a simple yet effortful physical task results in impaired cognitive control may be empirically important for understanding everyday functions of older and younger adults. For example, the ability to ignore task-irrelevant items may decline with age and this decline is greater when simultaneously performing a physical task.