Testing for the presence or absence of nystagmus is a routine part of every clinical, neurological examination. When this is done by moving the examiner's finger s-l-o-w-l-y across the visual field of the patient, one can also observe at the same time whether the patient's eyes follow the moving finger in a smooth manner or not. Occasionally it will be noted that the normally smooth pursuit movement is replaced by a saccadic motion. The eyes follow the moving finger in a series of short steps. They tend to overshoot the target, remain fixed for a brief period, and then advance ahead of the moving finger. The phenomenon differs from nystagmus inasmuch as it lacks the slow and fast component, is not present when the patient's gaze is held steady, and is not related to dysfunction of the vestibular-cerebellar system. The patient is usually subjectively unaware of the impaired performance and