People post-stroke perceive movement fluency in virtual reality.

We investigated the visual perception of biological movement by people post-stroke, using minimal kinematic displays. A group of twenty patients and a group of twelve age-matched healthy controls were asked to judge movement fluency. The movements to judge were either displayed as an end-point dot or as a stick-figure of the arm and trunk. It was found that the perception of movement fluency was preserved post-stroke, however, with an increase in the variability of judgment. Moreover, the end-point dot representation ameliorated what was perceived and judged, presumably by directing attention to the important kinematic cues: smoothness and directness of the trajectory. We conclude that, despite perception of actions is influenced by the ability of the observer to execute the observed movement, hemiparesis has a mild effect on the perception of biological movement. Yet, a valuable virtual learning environment for upper-limb rehabilitation should be implemented to provide the observer with neither too much, nor too little information to maximize learning.