Shifting the start: backward mislocation of the initial position of a motion

Participants asked to judge the final position of a moving target typically indicate a position shifted forward. In the 6 experiments reported here, participants were asked to indicate both the starting position (SP) and the vanishing position (VP) at the onset and offset of a moving target. Results confirmed the forward displacement of the VP and showed a backward displacement of the SP. To test whether perceptual estimation was influenced by curvature of the trajectory, curvilinear motions were also used. Results showed that apparent displacements are along the geometrical tangents to the SP and VP. Relationships between the results and other findings such as the flash-lag effect, the representational momentum, and the Fröhlich effect are discussed