Variations in normal color vision IV Binary hues and hue scaling

Abstract

We used hue cancellation and focal naming to compare individual differences in stimuli selected for unique hues (e.g., pure blue or green) and binary hues (e.g., blue-green). Standard models assume that binary hues depend on the component responses of red-green and blue-yellow processes. However, variance was comparable for unique and binary hues, and settings across categories showed little correlation. Thus, the choices for the binary mixtures are poorly predicted by the unique hue settings. Hue scaling was used to compare individual differences both within and between categories. Ratings for distant stimuli were again independent, while neighboring stimuli covaried and revealed clusters near the poles of the LvsM and SvsLM cardinal axes. While individual differences were large, mean focal choices for red, blue-green, yellow-green, and (to a lesser extent) purple fall near the cardinal axes, such that the cardinal axes roughly delineate the boundaries for blue vs. green and yellow vs. green categories. This suggests a weak tie between the cone-opponent axes and the structure of color appearance.

Biological origins of color categorization

“…Our proposal that the cardinal color mechanisms provide fault lines for infant color categorization is related to similar arguments made about adult color naming. For example, one study of adult color naming and hue settings provides evidence that the cardinal axes align with adults' blue-green and yellow-green category boundaries (45). Another study suggests that whether or not L-M cone-contrast between the color and background is positive (reddish) or negative (greenish) aligns with a common categorical distinction in WCS languages between warm and cool colors (33).…”

Empirical evidence for unique hues?

“…The circle was rotated randomly from trial to trial. According to the block, subjects were asked to choose, for example, "a red that is neither too orange nor too purple" or "an orange that is neither too red nor too yellow" [30]. The subject selected the segment he thought best matched the instruction, and a small achromatic disk appeared beside that segment.…”

Amodal Completion of Boundaries in Coloured Surfaces

“…In regard to the neurophysiological method, however, it should be pointed out that the use of neural correlates as explanatory criteria is still problematic (Malkoc, Kay, & Webster, 2005). Moreover, perception by itself has a very loose relationship with the underlying physics of colour due to metamerism and other relational factors (Adelson, 1995).…”