Human Action Perception is Consistent, Flexible, and Orientation Dependent.

Previous research has found that observers of object-directed human action pay more attention to information regarding hand contact over information regarding spatial trajectories in action, and that processing of trajectory information is disrupted by inversion. However, observers can also flexibly modulate their attention to spatial trajectory depending on the goal or context of the actor. In Experiments 1(a) and 1b of the current research, we directly compared attention with hand and trajectory information across placing and dropping actions in order to determine whether the hand bias is always present or whether flexibility in action perception can attenuate this bias. Results demonstrated that observers attend more to hand information for placing, but attend equally to hand and trajectory information for dropping. Experiment 2 explored the role of the actor's goal in processing spatial trajectory for mimed dropping actions and non-human control stimuli, and the role of goals in the inversion effect. Results indicated that goal relevance increases processing of trajectory information, and that processing of all spatial trajectories in human action is disrupted by inversion, regardless of the actor's goal. The present findings highlight the role of prediction in action perception, and suggest that human action is processed with expertise.