Visual jitter: evidence for visual-motion-based compensation of retinal slip due to small eye movements

When dynamic random noise is replaced by static noise after a period of ada ptation, adjacent unadapted regions filled with static noise appear to 'jit ter' coherently in random directions for several seconds, actually mirrorin g the observers own eye movements of fixation [Murakami, I. & Cavanagh, P. (1998). Nature, 395, 798-801]. The present study aims at psychophysically l ocating two distinct stages underlying this visual jitter phenomenon: a mon ocular, adaptable stage that measures local retinal motion and a compensati on stage that estimates a baseline motion minimum and subtracts it From mot ion vectors nearby. The first three experiments revealed that visual jitter has storage, directional selectivity, and spatial frequency selectivity, l ike the motion aftereffect does. These results suggest some overlap in the adaptation mechanisms for the two effects, possibly at or below the level o f primary visual cortex. The next two experiments revealed the transfer of the effect across the vertical meridian as well as the existence of a prefe rred stimulus size that is a linear increasing function of eccentricity, mi micking the RF size of the monkey MT neurons. These results suggest that so me extrastriate motion area along the parietal pathway including MT mediate s motion-based compensation of retinal slip. (C) 2001 Elsevier Science Ltd. All rights reserved.