The Use of Velocity Information in Movement Reproduction.

Previous studies suggested that movement velocity influence space perception. We examined whether healthy participants used velocity information when they were asked to reproduce a previously performed movement. Two experiments were carried out. In Experiment 1, blindfolded participants actively performed an arm movement (criterion movement, CM) at a natural velocity, or quickly, or slowly. After a brief delay, participants were asked to reproduce (reproduction movement, RM) CM-amplitude. No velocity constraints were imposed in making RM. In Experiment 2, CM was performed quickly or slowly. After a brief delay, the participants were asked to reproduce not only CM-amplitude but also CM-velocity. Experiment 1: in Natural condition, RM-velocity did not differ from CM-velocity and the participants accurately reproduced CM-amplitude. Conversely, in Fast and Slow condition, RM-velocities differed from CM-velocities and in Slow condition RM-amplitude was greater than CM-amplitude. Experiment 2: both RM-amplitude and -velocity did not differ from CM-amplitude and -velocity. The present study confirms the view that movement velocity influences selectively space perception and suggests that this influence is stronger for slow than fast movements. Furthermore, although velocity information is crucial in accurately reproducing CM-amplitude, it was not used spontaneously when movements were performed at unnatural velocities.