There was a Radiolab podcast on color that I listened to recently where they talked about the psychological aspect of color perception. It started with the scholarly work on color terms in classical Greek literature (that was referenced by Cecil and is commonly covered in anthropology classes) and went from there. It’s a very good primer on the subject, covering topics that I’d picked up from various different sources over the years, and introducing a few new tidbits that I hadn’t heard before.
They talked about tetrachromat vision, but surprisingly found that it may not provide much advantage over simply being very aware of color and cultivating perception — as a painter or other artist might. Their tetrachromat candidate (a woman with marker genes on both chromosomes) had the ability to distinguish very similar colors that normal people couldn’t distinguish, but wasn’t demonstrably more able than a normal trichromat female interior decorator, or even a male painter they asked to participate as controls in the informal study they staged for the show.
In the section on talking about what color the sky is, they brought up the idea that control or reproducibility is important in naming colors. You’d think that blue would be one of the easiest colors for languages to have a term for. The sky is “blue” after all, and some bodies of water are different shades of blue. Surprisingly, blue is one of the least common terms in languages.
The current theory is that color perception is influenced by both environmental cues and linguistic terms. This is not as reductive as the Sapir-Whorf hypothesis, but the lack of a word for a shade of color can lead to that difference being lumped together with another part of the spectrum as a non-distinctive difference. If you’ve got a word for that color, then there’s importance attached to it, so you train yourself to be aware of the distinction. You might not even perceive the difference if your linguistic and cultural upbringing doesn’t attach importance to doing so.
I think this is similar to the pruning we do when acquiring language. We can all hear the same sounds, physically, but the sounds we hear in the language or languages we acquire as our native languages heavily influences which sounds we perceive and which we are able to reliably distinguish. If you grow up with a click language, or tone language, you hear distinctive differences that are almost absurdly difficult for people to grasp whose native languages don’t feature those distinctions. In a very real sense, they are unable to “hear” those differences, despite the fact that their physical hearing apparatus is no different.
If you do some reading on how we process sight and sound, you’ll find that our brains do some seriously heavy interpolation and processing in order to change what we actually see or hear into what we think we see or hear. Sight, for example, is so process-intensive that there’s about an 80 millisecond lag between audible and visual perception. The amount of processing your brain has to do means that color perception is, to some degree, subjective. Your eyes and the eyes of a New Guinea tribesman are virtually identical, but you perceive things in extremely different ways due to cultural and linguistic differences.
Building on what Jragon wrote earlier about Japanese blue/green perception, there are different words for blue and indigo in Japanese, and most — if not all — Japanese do not consider them to be the same color at all. Since I learned about this curious difference, I’ve asked many different Japanese and been told by almost everyone that they are completely different colors, not shades of the same color. The few who have told me differently are suspect because they’re also fluent in another language and have spent some amount of time overseas.
Japanese also use both 橙 (basically, a species of orange) and オレンジ from the English. 橙 seems to describe the chunk of spectrum English speakers would consider orange all the way to an ochre color verging on brown. オレンジ is normally used for brighter orange colors.
The word for orange in Castilian Spanish is naranja (orange), which apparently either didn’t exist, or the native terms were supplanted when citrus fruits were introduced to Spain in the 13th century. I don’t know Catalan, but I’d suspect the root is very similar there.
These are both plausible examples of the introduction of a color term into languages that previously didn’t have a distinction. I don’t think anyone yet has done any research into color use before and after the introduction of a new color term to see if there is a difference in usage independent of dye and pigmentation technology. There’s a solid PhD’s worth of work on that subject, I’m sure.