Saccadic omission: Why we do not see a grey-out during a saccadic eye movement

We investigated why we have no perception of a smeared image resulting from the reduction in contrast (grey-out) occurring at the retina during saccadic eye movements. By turning on light in the experimental room only during the eye movement, we were able to show that this grey-out was perceived as a smeared image of the visual scene. However, when the experimental room was illuminated before and/or after the saccade as well as during the saccade, perception of the grey-out was obliterated. During a period of fixation, perception of a blank image comparable in duration to an eye movement could also be eliminated by a preceding or following clear image. We conclude that lack of perception during saccadic eye movements made in normal contoured environments results primarily from the visual “masking” effect of a clear image before and/or after the eye movement acting on the grey-out during the eye movement. This “saccadic omission” is entirely a visual phenomenon and is far more powerful than the usually studied elevation of visual threshold for detection of a flash, “saccadic suppression.”