Switching the motor response weakens confidence serial dependence.

"Confidence leak" (i.e., confidence serial dependence) is a phenomenon where confidence from a previous trial predicts confidence in a current trial independent of current choice or accuracy. Confidence leak has been shown to robustly occur across various cognitive domains and tasks. However, it remains unclear what factors, if any, modulate the strength of the confidence serial dependence. Here we investigate whether switching the motor response in a perceptual decision-making task influences the strength of the confidence leak effect. Subjects indicated the orientation of a Gabor patch using their left or right hand, with the response hand being randomly cued on each trial. We found that switching the response substantially weakened the confidence leak effect. We further replicated this finding in a second experiment in which left-hand responses were given using a keyboard and right-hand responses were given with a mouse. In both experiments, we also found that confidence leak was weaker whenever the left hand was used in the previous trial, suggesting that lack of motor fluency reduces the strength of confidence serial dependence. These results demonstrate that switching the motor response weakens serial dependencies and imply that the action required to make a choice can impact one's metacognitive evaluations.