Warm and cool reheated

Among more conventional perceptual attributes, such as hue brightness and saturation, color is universally assigned a value along a warm/cool dimension. The source of this aspect of color experience is uncertain and a subject of current debate in color science. An unpublished study from the late twentieth century has recently appeared in an online archive that makes publicly available the results of an extensive set of measurements that document the variation of warm/cool values throughout color space and shows that they relate simply to the sum of the red-green and blue-yellow opponent-color activations (red+yellow vs. blue+green), which the authors suggest is consistent with a sensory basis for this distinction. Warm/cool ratings replotted from Katra et al. (2023) are shown as open symbols and compared with the sum (dashed line) of average opponent-hue activations (red and blue lines). The similarity between the data and the sum is consistent with a neural basis for the warm-cool distinction.image