In pursuit of afterimage perception: Interactions with eye movements and contours

Abstract

Observers have long been directed to avoid making eye movements during colour afterimage experiments, with the assumption that they suppress afterimage visibility. One hypothesis is that saccadic eye movements lead to afterimage suppression because they distinguish an illusory afterimage from a real stimulus in a way that fixation cannot. Unlike an afterimage, no real stimulus remains at the same retinal location after a saccade, providing a cue that the afterimage is not real. Thus, pursuit eye movements would be less likely to result in afterimage suppression as real objects can remain predominantly stationary on the retina when pursed. Contrary to these predictions, we found no difference in afterimage duration in conditions when observers made saccadic and pursuit eye movements and when their eyes remained fixed. We also explored whether providing an additional cue that the afterimage may be real—a surrounding luminance contour- influenced afterimage duration across eye movement conditions. Results revealed that afterimage duration in the pursuit and fixation conditions was increased by the contour to a greater extent than the saccade condition. Thus, while eye movements appear not to interact directly with afterimage perception, saccades may alter their perception by interacting with other cues known to enhance afterimages.