We examined the time-course of saccadic suppression and tested whether it results entirely from retinal image motion or has an extraretinal component. Gratings were flashed before, during, or after either a voluntary 12-deg saccade or a saccade simulated by mirror motion. Suppression was found only for luminance-modulated gratings. Suppression starts 50 ms before, and is maximal at, saccadic onset where thresholds are increased tenfold. At lower luminance, the maximum becomes broader and weaker.
Simulated saccades produce shallower suppression over a longer time-course at both luminances.
Adding high-contrast noise to the display increased the magnitude and the duration of the suppression during simulated saccades but had little effect on suppression produced by real saccades. Saccadic suppression, specific to luminance-modulated stimuli, starts well before saccades. Differences between real and simulated saccades in the magnitude and time-course of sensitivity loss suggest that saccadic suppression has an extraretinal component. Saccadic suppression anticipates image motion and may provide immunity to its effects including conscious awareness of it during saccades.