You and the hand: investigating the effects of other-performed pointing movements on visuo-spatial memory

Previous studies have shown that self-performed pointing movements at encoding facilitate performance in a visuo-spatial recognition task. In the present study we investigated whether other-performed movements can produce similar effects and if the effect is limited to a human co-actor. Participants observed and were instructed to remember two consecutive arrays of three or four items, one encoded only by visual observation, the other by visual observation accompanied by pointing movements. In three experiments, pointing movements were performed either solely by the experimenter (Exp. 1), or by the participant alternating with the experimenter (Exp. 2) or with an animated hand (Exp. 3). We found that pointing movements performed by the experimenter facilitated array recognition only when they were alternated with self-performed movements. The same results hold when the human co-actor was replaced by an animated hand in Exp. 3. The results suggest that observing others performing the movement leads to active motor simulation only when it is associated to the self- execution of the same movement.