Representing and anticipating human actions in vision

Visual perception of human actions was investigated in a long-term priming experiment. On each trial in the priming phase, participants were presented with a pair of short motion animations showing a person performing a particular whole body movement and had to decide whether the actions were the same or different. In the testing block, the same observers had to determine whether static pictures of a human model showed a possible or an impossible body pose. For each test posture, a subject either (1) had seen a priming animation in which the actor would have reached the test posture if the animation had lasted longer, (2) had seen an animation in which the actor would have been in the test posture if the animation had started earlier, or (3) had not seen a related priming animation. Reliable facilitatory priming effects were obtained only when the test posture was preceded by a motion sequence that would have resulted in the test posture if the human model had continued the action. The findings support the hypothesis that, when confronted with a human action, observers anticipate the future posture of the actor and that this anticipation facilitates later identification of the posture.