When a first saccade is made in response to a single, suddenly appearing stimulus it often misses the target. The retinal error may be very large, in particular in those cases where the subject anticipates the target location and initiates a saccade to a wrong position. We have analyzed the time of the occurrence of the secondary saccades by which the subject corrects these errors. Using the gap
... [Show full abstract] task with random target locations we found that large errors after anticipatory saccades--especially those after direction errors--can be corrected very fast. The latencies of these corrective saccades (being measured from target onset, not from the end of the primary saccade) form bimodal distributions with a first peak at 100 ms. It is therefore concluded that large errors can be corrected by express secondary saccades.
