Abstract
Physical and cognitive effort often interact with each other and 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 LC-NE activity. It is still unclear whether the effects of physical and cognitive effort on pupil size, a proxy measure of the LC-NE activity, are independent of one another or interactive with each other. To address this question the present study examined the impact of engaging in a concurrent effortful physical and cognitive task on task evoked pupil responses (TEPR). Physical effort was manipulated by having participants grip a hand dynamometer at low versus high force (e.g., 5% vs. 40%) of individual strength. Cognitive effort was operationalized as Working Memory load in a Change Detection task where the participants attempted to remember 3 or 5 briefly presented orientation bars and then report, after a short retention interval, whether a randomly chose memory item changed orientation or not. In line with prior research, our preliminary data suggested that pupil size increased with physical exertion. However, unlike prior findings, the present study found that pupil size decreased from low cognitive load (i.e., memory set size 3) to high cognitive load (i.e., memory set size 5) during the WM maintenance period. In addition, these two effects seem independent of each other. Follow up studies are undergoing to further investigate the effect of concurrent physical and cognitive efforts on pupillary responses.