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Richard Plummer, James Brown, Jaeseon Song; Using artificial scotoma fading to explore antagonistic interactions in figure-ground perception.. Journal of Vision 2018;18(10):805. doi: 10.1167/18.10.805.
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The perceptual fading experienced with an artificial scotoma can be viewed as a failure of figure-ground segregation making it a useful tool for investigating possible mechanisms and processes involved in figure-ground perception. Weisstein's model of figure-ground perception is based on antagonistic dorsal-M and ventral-P pathway interactions in the visual system where activity in the ventral-P stream encodes figure/foreground and activity in the dorsal-M stream encodes background (Weisstein, Maguire, & Brannon, 1992). Where a boundary separates two regions, which region is perceived as figure and which as ground is determined by the outcome of antagonism between dorsal-M and ventral-P signals both within each region and across the boundary between them. The region with the relatively stronger ventral-P "figure signal" is ultimately perceived as figure, the region with the relatively stronger dorsal-M "ground signal" is perceived as ground. From this perspective artificial scotoma fading occurs when the figure signal is overwhelmed by the ground signal. Therefore, anything strengthening the figure signal or weakening the ground signal should make the figure more resistant to fading. Our strategy used red (Exp's 1 & 2) and blue (Exp 2) light to reduce dorsal-M activity in both figure and ground regions based on research showing red light suppresses M activity and blue cones provide minimal input to M ganglion cells. Our figure was a 2°x 2° homogeneous square located 10° from fixation against a random-dot background. Time to fade (TTF) from stimulus onset until the figure completely disappeared was measured. Every possible combination of gray, green, red, and blue as figure and/or ground was tested. The results supported our predictions with TTF being greatest when red or blue light either (1) strengthened the figure signal by reducing M activity in figure, or (2) weakened the ground signal by reducing M activity in ground.
Meeting abstract presented at VSS 2018
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