Perceptual extrapolation of body movements is driven by internal models of others’ body

Vandenberghe, Antoine [UCL] Vannuscorps, Gilles [UCL]

After a moving object has disappeared, people typically mislocate its final position to where it would have been if it had continued to move for a few milliseconds. This “representational momentum” (RM) is reduced for body movements that would have been biomechanically difficult to continue along the same trajectory. This has been considered compelling evidence that perception of body movements is supported by motor simulation and tuned by the body abilities of the observer. The two studies reported here tested the alternative hypothesis that body movement perception is tuned to the body abilities of others, learned through visual experience. In Experiment 1, we first used two pictures to familiarize participants with the maximal amplitude of arm movement of a flexible and a rigid actor. Then, they performed a RM task in which they watched video-clips depicting the actors performing either a movement of maximal amplitude (80% of trials) or of an intermediate amplitude (20%), that is, a movement that would have been easy to continue for the flexible actor, but impossible for the rigid actor. Before the start, participants were told to pay attention to the identity of the actor, which could help them solve the task. In Experiment 2, there was no such instruction, nor any familiarization phase. Although the intermediate movement was identical for both actors, the RM was consistently larger for the flexible actor. This indicates that perceptual extrapolation is shaped by knowledge of actor-specific biomechanical abilities.