Express saccades and visual attention

Abstract

One of the most intriguing and controversial observations in oculomotor research in recent years is the phenomenon of express saccades in monkeys and man. These are saccades with such short reaction times (100 msec in man, 70 msec in monkeys) that some experts on eye movements still regard them as artifacts or as anticipatory reactions that do not need any further explanation. On the other hand, some research groups consider them not only authentic but also a valuable means of investigating the mechanisms of saccade generation, the coordination of vision and eye movements, and the mechanisms of visual attention. This target article puts together pieces of experimental evidence in oculomotor and related research-with special emphasis on the express saccade-to enhance our present understanding of the coordination of vision, visual attention, and the eye movements subserving visual perception and cognition. We hypothesize that an optomotor reflex is responsible for the occurrence of express saccades, one that is controlled by higher brain functions involved in disengaged visual attention and decision making. We propose a neural network as the basis for more elaborate mathematical models or computer simulations of the optomotor system in primates.

Trial by trial effects in the antisaccade task

“…Stimuli were displayed using a Viewsonic P225f Trials were also excluded if saccades were initiated within 80 ms of the appearance of the peripheral target as these are unlikely to have been generated in response to the target, even given express saccade latencies (e.g., Fischer and Weber, 1993;Wenban-Smith and Findlay, 1991); such rapidly initiated saccades are likely to be anticipatory. Trials were also excluded if no eye movements were initiated within two seconds of the appearance of the peripheral target.…”

Visual half-field experiments are a good measure of cerebral language dominance if used properly: Evidence from fMRI

“…Another reason for obtaining better results with bilateral presentation may be that the stimulus onset in unilateral presentation is a strong attention catcher, which may lead to express saccades. These are very rapid reflexive eye movements to a stimulus onset and can be initiated within a time period as short as 80 ms (Fischer & Weber, 1993). Finally, as we will see below, bilateral presentation also allows presentation of stimuli for a longer time.…”

Manual responses to visual stimuli: early and late facilitatory effects due to the offset of a peripheral cue

“…When the FP remained on throughout the trial (overlap paradigm), the mean SRT was about 250 ms; when the FP offset was simultaneous to the stimulus onset (gap 0), the mean SRT was about 200 ms; and when the FP disappeared 200 ms before the target onset (gap paradigm), SRTs decreased to about 150 ms. This reduction on SRTs has been called "the gap effect" (for details (7) ).…”

“…In humans, the first peak occurred around 100-120 ms and the second one occurred around 160-180 ms. The very short latency group in the SRT distribution was called Express SaccadesESs (7) . According to Fischer, "express saccades are defined by their extremely short reaction times (70 ms in monkey, 100 ms in man), which often form a separate peak in the reaction time distribution" (7) (p. 553) -bimodal distribution criterion.…”

“…The very short latency group in the SRT distribution was called Express SaccadesESs (7) . According to Fischer, "express saccades are defined by their extremely short reaction times (70 ms in monkey, 100 ms in man), which often form a separate peak in the reaction time distribution" (7) (p. 553) -bimodal distribution criterion. Moreover, after training, some subjects were able to reduce or even eliminate the later peaks, thus resulting in an unimodal distribution with a single peak around 100 ms (7) -absolute latency criterion.…”