A brief note. I just ran across “Brightness and Darkness as Perceptual Dimensions” on PLoS. I can’t say I fully grok the contents, but the authors suggest that brightness and darkness behave not simply as polar opposites, rather as axes of a brightness-darkness space (i.e., the brain processes the two differently). Hrm.

As the authors state, “Vision scientists have long adhered to the classic opponent-coding theory of vision, which states that bright–dark, red–green, and blue–yellow form mutually exclusive color pairs.” But, “Here we provide direct evidence that brightness and darkness form the dimensions of a two-dimensional (2-D) achromatic color space. […] Our 2-D model generalizes to the chromatic dimensions of color perception, indicating that redness and greenness (blueness and yellowness) also form perceptual dimensions. Collectively, these findings suggest that human color space is composed of six dimensions, rather than the conventional three.”

Definitely merits a closer reading…