Abstract
When the environment changes color, vision adapts, and the world gradually appears less tinted. For repeated color changes, vision may learn to adapt faster to maintain accurate perception. We previously reported that wearing red glasses repeatedly caused the world to appear less and less reddish when the glasses were first put on, as measured by the appearance of unique yellow. Here, we tested the appearance of a larger range of colors. 13 observers wore red glasses for 5hr/day for 5 days. Observers were tested with pairs of 1.5 deg filled color circles, centered within a 6deg black square on a background image. 13 colors were chosen from LAB space comprising unique and intermediate hues at two contrast levels, and one gray. Observers rated the difference between each possible color pair on a scale of 0 to 9. Observers performed the task before and immediately after putting the glasses on, and after 25, 50 and 75 min of wear. Wearing red glasses caused all colors to appear reddish and be rated as relatively similar. As observers adapted, colors gradually regained more normal appearance, and the similarity between color pairs decreased. Critically, over days, color pairs appeared more dissimilar immediately after putting on the glasses (p<1e-6). Multi-dimensional scaling analysis of the similarity data revealed a uniform expansion of color space across days. Thus, observers learned to immediately adjust their perception of many colors with repeated experience.
 Funding: Funding: NSF-1558308