Color qualia—the subjective experience of color, such as the quality of redness—are similar across age and culture. Using a task that obtained pairwise similarity judgments via intuitive visual interfaces, researchers tested children aged 3 to 12 in Japan and 6 to 8 in China, comparing them with Japanese adults. About half of 3-year-olds completed the touch-panel task reliably. Despite developmental and cultural differences in color-term usage, color qualia structures were quite similar across all groups. This suggests that these structures emerge early in life. Subtle age-related differences in evaluations of some color pairs imply minor changes in color experience with development.
The qualitative aspects of consciousness (qualia) are difficult to study because they are subjective. This work takes a first step toward linking the structure of qualia to brain activity by comparing human dissimilarity ratings of visual motion experiences with neural population responses in mouse primary visual cortex. Human participants (N=171) rated dissimilarity of 48 visual motion stimuli. Mouse neural activity (n=751 neurons) was recorded from nine mice using optical imaging. Both human and mouse data showed structural commonalities: a categorical organization of stimulus direction best explained both structures. These commonalities were similar in awake and anaesthetized mice, suggesting coarse V1 geometry is relatively insensitive to this anesthesia. The authors note that future work combining behavior with causal intervention is needed to relate such neural structures to conscious experience.
A new method based on optimal transport can align the similarity structures of color experiences between people without assuming which colors correspond. After collecting subjective similarity judgments for 93 colors, the method correctly aligned the color qualia structures of color-neurotypical participants at the group level, but could not align the structures of color-blind participants with those of color-neurotypical participants. This provides quantitative evidence that color-neurotypical people's experience of "red" is relationally equivalent to other color-neurotypical people's "red", but not to color-blind people's "red". The method can be applied across sensory modalities.