Mislocalization of targets flashed during smooth pursuit depends on the change in gaze direction after the flash

Subjects mislocalize the position of a target that is flashed while they are making pursuit eye movements. This mislocalization is in the direction of pursuit. However, it is not clear whether it is the movement of the eyes or the movement of the pursuit target that matters. Neither is it clear whether it is the movement after the flash or the movement before the flash that matters. To resolve these issues, we asked subjects to pursue a disk that regularly changed its movement direction. Each change was followed by a change in the direction of gaze movement. Subjects were asked to tap targets that were flashed close to the moment at which the pursuit disk changed direction. We measured the movements of the eyes, head, and index finger. Subjects did not make saccades to the position they tapped but kept pursuing the disk. We compared the direction of the mislocalization with the changes in gaze and in target position during different intervals relative to the flash. We found that the mislocalization is related to the change in gaze after the flash.