Simple movement imitation: Are kinematic features sufficient to map perceptions into actions?

The aim of this study was to pinpoint the nature of the visual features used in the automatic mapping of perceived movements into similar executed movements, following the direct matching hypothesis. In Experiment 1 subjects imitated the lifting of one of two fingers, presented with different orientations. As predicted, stimuli which were further rotated away from the posture of the executing hand elicited slower reaction times. In Experiment 2, we verified that this orientation effect was not a purely perceptual effect by presenting the same stimuli but asking subjects to respond verbally. No orientation effect was found using a verbal response. In Experiment 3, we replaced the moving fingers by two arbitrary objects moving with the trajectories of the finger tips of Experiment 1. The same orientation effect as in Experiment 1 was observed. We conclude that in this experiment participants are using purely kinematic features to map perceived into executed movements.