Recall of observed actions modulates the end-state comfort effect just like recall of one’s own actions

Abstract

Previous studies showed that initial comfort of a posture is traded for a better control at the end position, a phenomenon which has been termed the end-state comfort effect. When participants recall a recently performed motor plan, the end-state comfort effect is reduced. Two experiments investigated whether observing the grasp of another person is sufficient for later recall. Participants moved an object from a home location to different target positions. Results replicated an end-state comfort effect, revealing an inverse relation of grasp height to target height for the first movement. When participants later returned the object back to the home position, recall of the previously self-performed action dominated, replicating the reduction in end-state comfort due to recall processes. Notably, the end-state comfort effect was also reduced in conditions in which a model performed the first movement and in which the participant performed only the second movement (Experiment 1). Model actions were also recalled in situations in which the observed action was incongruent with a comfortable end position of the participant (Experiment 2). These results suggest that observed actions of others can serve as templates for movement planning in social situations.