Express saccades: is there a separate population in humans?

Abstract

It is well known that the latencies of target elicited saccades are significantly reduced when the target onset is preceded shortly by the offset of a fixation point (Saslow 1967). Fischer and Boch (1983) reported the discovery that, with monkeys as subjects, in addition to the general reduction in saccade latencies previously reported, there occurred a separate population of saccades with extremely short reaction times. They termed this population "express saccades", and more recently reported the discovery of an equivalent population of express saccades for humans (Fischer and Ramsperger 1984; Fischer 1987). In this paper, work is reported which confirms the existence of short latency visually guided saccades in humans but questions whether these form a separate population of "express saccades". The conditions used were very similar to those used by Fischer and Bocn.