“LANGUAGES divide the spectrum up in different ways. Welsh speakers use “gwyrdd” (pronounced “goo-irrrth”) as a general word for green. Yet “grass” literally translates as “blue straw”. That is because the Welsh word for blue (“glas”) can accommodate all shades of green. English-speaking anthropologists affectionately squish “green” and “blue” together to call Welsh an example of a “grue” language. A few of them think grue languages are spoken by societies that live up mountains or near the equator because ultraviolet radiation, which is stronger in such places, causes a progressive yellowing of the lens. This, the theory goes, makes the eye less sensitive to short wavelengths (those that correspond to the green and blue parts of the spectrum). Unfortunately, though the Welsh do live in a hilly country, it is hardly mountainous enough—let alone sunny enough—to qualify.
The ultraviolet theory, however, is just one idea among many in the debate about the psychology of colour. Like many debates in psychology, this one pits congenital, fundamentally genetic, explanations against explanations that rely on environmental determinism. Psychologists in the former camp think people are born with ingrained ideas about how hues are grouped. They believe the brain is preconditioned to pick out the six colours on a Rubik’s cube whatever tongue it is taught to think in. The other camp, by contrast, thinks that the spectrum can be chopped into categories anywhere along its length. Moreover, they suspect that the language an individual learns from his parents is the main explanation for where that chopping takes place.
… There is a fundamental—presumably congenital—distinction, as shown by the fact that the non-linguistic side of the brain distinguishes between blue and green. But there is also a language-mediated one, as shown by the linguistic side’s greater response.”
article link from the clever lucaskrech, lighting engineer extraordinaire