Abstract
Around the time of saccadic eye movements, visual performance is deteriorated in multiple ways in visual space, while performance at the saccade target location is enhanced. In this study, we investigate luminance detection across a large part of visual space during saccades. Subjects seated in an illuminated room detected a brief achromatic probe stimulus while executing a 20 degree rightward saccade. The probe was a 1 x 1 degree square of varying luminance that flashed for a single frame (6.67 ms) on a gray background (2.74 cd/m2) of a CRT monitor. The probe appeared randomly at 13 discrete locations, spaced 4 degrees apart, covering 48 degrees of visual space along the horizontal meridian, and encompassed the fixation point and the saccade target. Both the fixation point and the saccade target consisted of 0.5 degree diameter green circles that were subjectively equiluminant to the background. The cue to initiate the saccade occurred randomly within a 1000 ms time window, and was provided by the simultaneous offset and onset of the fixation point and saccade target, respectively. Luminance detection thresholds were obtained at multiple saccadic epochs by means of a generalized linear model using maximum likelihood estimation. Thus far, more than 40,000 saccadic trials have been collected from each of two subjects. For both subjects we find a consistent pattern of luminance detection thresholds as a function of time and space. In particular, thresholds at peripheral locations were substantially elevated immediately at saccade onset. In contrast, detection thresholds within a region containing the fovea and the spatiotopic location of the saccade target remained relatively low, suggesting a preferential processing of this region throughout saccadic eye movements.
Meeting abstract presented at VSS 2012