The direction of perceptual displacement of a moving target’s starting and vanishing points: the key role of velocity

Individuals make localization errors when asked to localize the perceived onset (starting point; SP) and offset (vanishing point; VP) of a moving target. For VP, a position shifted forward is usually indicated, whereas for SP two conflicting spatial mislocations are reported (i.e., one in the direction of motion and the other in the direction opposite to motion). Three experiments are presented, aimed at testing the influence on SP and VP errors of the modulation of target's velocity in the first, central, and last part of a horizontal or vertical motion path. A forward VP displacement was obtained, whereas for SP a backward displacement proved significant only for horizontal motions. Velocity modulation had an effect only on VP mislocation (Experiment 1), and this effect was due to instantaneous velocity at VP (Experiment 2). These results are discussed in light of the hypothesis that a low-level mechanism is responsible for both SP and VP mislocations. © 2008 Japanese Psychological Association.