Abstract
It is well established that perceived colors are altered by simultaneously or successively presented neighbors, and mutual repulsion between contiguous colors has been attributed to lateral inhibition and adaptation. Here we present evidence for sequential attraction in color perception. This novel perceptual phenomenon could bias identification and discrimination measurements, and affect integration of color with form and motion. Serial dependencies for ambiguous motion, ambiguous figures, and orientation, have been attributed to integrating current input with past information, as part of pattern completion, inherent storage, continuity field, etc. The underlying prior being that constancy of object properties is generic in the physical world, so that sudden change in object properties is attributed to environmental transients. We used sequences of colors, within and across color mechanisms, to examine the neural substrate of sequential attraction across abrupt changes. On each trial, observers fixated a 4o colored target disk for 500 millisecond. A random noise square glided over the disk revealing a changed color. Observers adjusted the color to match the target. The noise square again occluded the disk and revealed the next target. Sequential targets were chosen randomly from an isoluminant red-green line, or the circumference of a color circle. The signed error for matches along the red-green line, plotted against the signed deviation between the matched target and the preceding target, showed a skew-symmetry demonstrating that matches were attracted towards the color of the preceding target (3 color-normal observers). However, sequential attraction was not seen for matches around the color circle. Choosing between the two possibilities that sequential attraction happens within color mechanisms but not across, or that attraction happens within stimuli that are represented as a single dimension but not across multi-dimensional representations, requires further experimentation. Unraveling the neural processes of color attraction may help understand sequential dependencies in other domains.
Meeting abstract presented at VSS 2016