Categorical perception
Chapter 5 endnote 1, from How Emotions are Made: The Secret Life of the Brain by Lisa Feldman Barrett.
Some context is:
Your brain downplays the variations within each color category and magnifies the differences between the categories, causing you to perceive bands of color [in a rainbow]. [...] This process is called “categorical perception.”
Categorical perception occurs when you have a continuous phyiscal space but you perceive categories with boundaries (so it is a sort of perceptual distortion where some things that are experienced as more similar than they are physically and some things are experienced as less similar than they are (because your brain is ignoring some differences and emphasizing others to make them larger than they actually are). It is a perceptual distortion of physical space.[1] We see a rainbow with stripes because some wavelengths of light are experienced as the same color, whereas other wavelengths that are separated by the same distance in nanometers are experienced as different colors.
Rainbow perception in other cultures
Chapter 7 includes a picture of a rainbow as seen by a Russian perceiver (figure 7-2). My graduate student Jiahe Zhang also tells me: "In Chinese, the colors of the rainbow are listed as red, orange, yellow, green, QING, blue and purple. Blue is now listed one position later than in English, and the fifth spot is occupied instead by QING, which in Chinese is a color similar to cyan. QING/cyan is not a widely used color word in modern Chinese. When it is used outside the rainbow context, it takes on a wide range, from many shades of green and blue to even black."[2]
See also
- Snopes has an interesting discussion on indigo, including the 7 Russian color words.