Movement interference in imitative rhythmic arm movements

Previous studies have shown that observing an action interferes with the performance of a similar but non-identical action. This interference effect may occur while observing some effectors (e.g., humans, dots) and not others (e.g., humanoid robots). In one experiment we examined what aspect of movement causes the interference effect. Subjects made arm movements in two opposite diagonal directions while watching a video of either a human making similar arm movements or a dot moving on the screen following the path of the fingertip. The human video and the dot moved at either the natural velocity (NV) or at a constant velocity (CV). The subjects executed either congruent (same direction) or incongruent (opposite direction) movements with respect to the stimuli. In the other experiment we looked at whether the perspective of observing the movement affected interference. We looked at interference from observing the mirror-arm (specular view) and observing the anatomical arm (third-person view). These studies will help us understand the key determinants of this interference effect (such as the congruency, velocity profile or stimulus type) as well as shed light on the different pathways engaged by the Action Observation Network when involved in imitation.