Pointing performed by others facilitate visuo-spatial memory, but how much should I be involved?

Several previous studies have investigated how the production of movements influences visuo-spatial working memory. Specifically, it has been shown that self-performed pointing movements facilitated the recognition of spatial arrays in a visuo-spatial working memory task. In the present experiments we examined the effects on memory of pointing movements that were either self-performed or performed by others. Participants were administered a task that required the maintenance of two consecutive arrays of three or four items, one encoded only by visual observation, the other by visual observation accompanied by pointing movements (performed either by the participant or by the experimenter). In three experiments, the percentage of trials involving self-performed pointing movements was varied from 50% (Exp. 1), to 16.66% (Exp. 2), to 0% (Expt 3). We found that experimenter-performed movements facilitated array recognition only if alternated with self-performed movements. The positive effect of pointing remained significant even when the frequency of self- performed movements was restricted to 16.66% (1/6 of the total number of trials). These results suggest that other-performed movements can improve visuo-spatial working memory performance, as long as they are alternated with self-performed movements. We propose that this benefit reflected either motor simulation or richness of encoding.