Velocity noise due to small eye movements in motion vision

Abstract

Small eye movements incessantly make velocity noise in the retinal image, but our visual world always looks stable. It is proposed that the brain assumes spatially common motions in the retinal image as originating in eye movements, interpreting relative image motions only as originating in object motions. Two compelling illusions, the jitter aftereffect and on-line jitter, support this idea. When motion sensitivity in a surround region is lowered either by adaptation or by synchronous flicker, a central region, now made uncommon relative to its surround, appears to jitter, reflecting small eye movements. Moreover, a motion detection experiment revealed that small eye movements reduce our sensitivity for uniform motion, without affecting relative-motion sensitivity, as predicted by the proposed theory. It is discussed that, in principle, this biological noise-reduction mechanism in the visual system can be applied to artificial motion sensing systems aiming to extraction of fine motion signals from noisy visual inputs.