ABSTRACT
It is well known that a target presented at about the time of a saccade is perceptually mislocalized. Some studies report, however, that, in contrast to perception, the eye is directed to the actual position of the target. We examined this discrepancy by comparing oculomotor (saccadic) and perceptual localizations of a target flashed at about the time of a prior saccade. The results showed that the perceptual mislocalization is a time function. Targets flashed before and at the beginning of the saccade were mislocalized in the saccade direction. About midway through the saccade, the targets were localized near the actual position. At the end of the saccade, the targets were mislocalized in the opposite direction from the saccade. Oculomotor localization showed a similar mislocalization to the perceptual judgment: The eye moved not to the actual target position in space, but to its perceptually judged position. The results were interpreted as showing that perceptual and oculomotor localizations were based on the same extraretinal eye position information that was not properly timed to the actual eye position. Therefore, the results were not consistent with strict "spatial models" of the saccade system, which assume that saccade target are localized with respect to head or body. The detailed analysis of the oculomotor responses supported some findings on the saccade system reported by earlier double step stimuli experiments.
