Estimation of discrepancy of color qualia using Kullback-Leibler divergence.
Bio Systems October 1, 2023 Miku Yamada, Miu Matsumoto, Mina Arakaki et al.
By asking 306 subjects to pick which of six colors they felt was the true red, light green, blue, yellow, or purple, researchers built probability distributions for each color. They then used Kullback-Leibler divergence to measure the difference between the reference color's distribution and that of each generated color. The number of subjects who selected a generated color decreased as its Kullback-Leibler divergence from the reference increased, but the rate of decrease varied greatly across colors. This suggests that color qualia—the subjective sensation of a color—are not uniform across hues; people appear to randomly choose a color that 'feels' right.