Abstract
Cognitive and physical activities often occur concurrently in daily life. The present study therefore aims to assess the effects of a simple(est) physical effort (i.e., isometric handgrip) on a core cognitive process, working memory (WM) encoding. It is the process of transforming fragile perceptual representations into durable working memory representations that may play an important role in supporting and constraining other core cognitive processes. Specifically, the participants performed a visual WM change detection task while squeezing a hand dynamometer with different levels of exertion that are proportional to their maximum voluntary contraction (MVC). WM encoding time was experimentally manipulated by pattern masks inserted at varied memory-and-mask Stimulus Onset Asynchrony (SOA) during the retention internal. On the one hand, isometric handgrip can induce physical arousal and subsequently speed up WM encoding in a similar way as emotional arousal (i.e., Arousal Hypothesis). On the other hand, isometric handgrip exertion may impair WM encoding due to the potential competition for metabolic and cognitive resources shared between the two tasks (i.e., Resource Competition Hypothesis). Our preliminary data showed that WM encoding slowed down from a low level of concurrent physical effort to a moderate level of physical effort, supporting the Resource Competition Hypothesis. Follow-up experiments are planned to test whether altered time perception by concurrent physical effort could account for the effects of physical efforts on WM encoding.