Movement adaptation in the peripheral retina.

With strict fixation, the eye quickly adapts to moving periodic stimuli presented to the peripheral retina. A slowly spinning sector disk, 7 degrees in diameter, will rapidly appear to slow down and come to a standstill (within 5-25 sec). The time required for this full motion adaptation decreases with (a) increasing retinal eccentricity (30-70 degrees); (b) increasing number of sectors (16-60); and (c) decreasing speed of rotation (0.3-0.5 rev/sec). After the standstill, the disk fades from view in much the same way as a stationary stimulus (Troxler effect). A spinning disk presented to the temporal retina appears to stop about 2.5 times faster than a disk presented to the nasal side. Adapting one eye reduces the time of adaptation for the other eye by 70%. If an aperiodic sector disk is used, no standstill is perceived.