The role of physical and cognitive effort on time perception.

Action and perception are intertwined, and time perception is not an exception to this general principle. In line with that, we have recently reported that the perceived duration of visual stimuli is extended while running. Here we tested the nature of this phenomenon by contrasting two possibilities: one related to physiological changes induced by physical effort (e.g. heart rate, temperature, arousal), and one related to cognitive alterations linked to motor control. To this aim we compared the direction and magnitude of the temporal bias induced by running to that prompted by other two conditions requiring much lower physical effort but both depleting cognitive resources. In these two conditions, participants either performed the timing task while walking backwards (an attentional motor task) or standing still with cognitive resources divided in a concurrent visual-working memory task. Both conditions yielded temporal overestimations virtually identical to that found while running, suggesting that physical activity could modulate temporal processing through the cognitive effort required to perform/control that specific motor routine. The results are informative for the scientific community investigating time perception in ecological sensorimotor contexts, suggesting the importance of considering the potential confounding role of cognitive factors related to motor execution.