Abstract
Working Memory Capacity (WMC) is related to maintaining relevant visual representations while simultaneously inhibiting irrelevant ones. Are individual differences in WMC related specifically to inhibitory processes? Here the perceptual phenomenon of color filling-in over chromatic, binocularly rivalrous stimuli reveals that inhibitory processes are indeed related to individual differences in WMC.
Participants viewed an array of equiluminant ‘red’ and ‘green’ dots within a ‘yellow’ background in each eye. Retinotopic locations that contained a red dot in one eye had a green dot in the other eye (after Kovács et al., 1996). This established binocular color rivalry for each dot in view. As reported by Kovács et al., observers sometimes reported seeing (1) an array of all red or all green dots or (2) filling-in of the yellow background, which gave the percept of a uniform yellow field (thus, visual inhibition of the binocularly rivalrous red and green dots). Separately, WMC was assessed individually for each participant using the RSPAN measure (Conway et al., 2005).
Greater WMC was directly related to the frequency (r=0.41, p<0.01) and stability (r=0.26, p=0.056) of only the filled-in uniform yellow percept. A control condition ruled out Troxler's fading as the cause of these results. This experiment establishes a clear link between WMC and inhibitory processes. It also demonstrates a novel relation between WMC and visual percepts by highlighting the connection between human working memory capacity and lower-level processes determining perceptual coherence.
Supported by NIH grant RO1 EY-04802.