Observing a human or a robotic hand grasping an object: differential motor priming effects

Abstract

Abstract Abstract. The present paper aims to investigate how functional connections between action and perception may contribute to our imitation of motor acts of other beings. Four experiments examined motor priming effects on imitation from biological and nonbiological effector systems. In Experiment 1 we asked subjects 1rst to observe grasping movements performed by a human actor and by a robotic hand, and subsequently to perform the same movement. For 80% of the cases the movement performed by the primer and that performed by the subjects were directed to the same object (valid trials). For the remaining 20% of cases the subjects were required to perform an action towards an object that differed in size from the object grasped by the primer (invalid trials). Experiment 2 was similar to Experiment 1 except that the ratio between valid and invalid trials was 50%. We found priming effects con1ned to when a human actor served as the primer. In Experiment 3 we showed that the selective effects found for the human primer in Experiment 1 were unrelated to the fact that, in the robot condition, only an arm/hand system was visible while for the human actor both the face and the upper body were visible. Experiment 4 demonstrated some differences between the robot and a human primer even when the kinematics of the human primer did not change as a function of object size. The results demonstrate that motor priming can occur from the observation of biological action.