Long-range twinkle induction: an achromatic rebound effect in the magnocellular processing system?
After viewing a blank region surrounded by a dynamic noise stimulus, viewers report the perception of prolonged dynamic twinkle in the unstimulated blank region. This twinkle aftereffect may be induced over long ranges in the visual field, up to 10 degrees from the edge of the noise in central vision. Our previous studies of the properties of this aftereffect suggested mediation by the magnocellular processing system. We therefore evaluated the properties predicted by the magnocellular hypothesis by varying the coloring, the temporal and the spatial frequency of the stimulus. No aftereffect could be induced by an equiluminant color stimulus or by luminance noise below the temporal frequency of 5 Hz. The aftereffect obtained by luminance noise above 5 Hz was stronger for larger inducing elements. These results are consistent with known properties of the magnocellular processing system.
Smith-Kettlewell Eye Research Institute, San Francisco, CA 94115, USA. cwt@skivs.ski.org
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D003118:Color Perception; D003196:Computer Graphics; D015350:Contrast Sensitivity; D005366:Figural Aftereffect; D006801:Humans; D011581:Psychological Tests; D012858:Size Perception