Motion extrapolation is not responsible for the flash-lag effect

To achieve perceptual alignment between a flashed target and a moving one, subjects typically require the flashed target to be aligned with a position that the moving target will only reach some time after the flash (the flas h-lag effect). We examined how the magnitude of this misalignment changes n ear an abrupt change in velocity. The magnitude of the misalignment turns o ut to depend on the target's velocity after, rather than before, the flash. Thus, the misalignment cannot be caused by motion extrapolation. Neither c an it be the inevitable consequence of a difference between the time it tak es to process flashed and moving stimuli, because the magnitude of the misa lignment is influenced by the extent to which subjects can anticipate the f lash. We propose that it is the consequence of having to 'sample' the movin g target's position in response to the flash. (C) 2000 Elsevier Science Ltd . All rights reserved.