[sega_sai]

One thing that I find interesting when thinking about colour perception, is that even if two people agree that a given colour is red, there is no way to know (as far as I am aware) that they actually perceive it in the same way. Maybe the brain of one person paints it red, and another paints it differently, and there is no way to know as we can't get into other people's heads.

[layer8]

That’s assuming that there is something like a “true” internal color that external colors are mapped onto. I think it’s more likely that for the brain, “red” is just “that hue signal range that red things have”. Which is roughly the same for everyone (modulo color blindness), in the sense that if one person sees two objects as red, another person will also see them as the same color, and will perceive the same brightness and hue relation relative to other objects with adjacent brightness and/or hue.

Meaning, there is no absolute color, the brain just learns what things have the same color, and how similar or dissimilar they are in hue to other objects. And for example “cold” colors are cold because we associate them with cold things, not because of some independent “qualia”.

[MarkLowenstein]

My suggestion is always to look at what colors people think "go together". A Westerner looking at a Chinese temple will say "ugh, saturated red, light blue, and gold, all together?" My own self looking at a shirt my Eastern European wife loves: "dark blue, gray, and orange, bleah". It suggests that depending on your culture, you may have adopted a different visual response, where blood color is harmonious with sky color, or something like that.

[keane]

Quite right: https://en.wikipedia.org/wiki/Qualia

[shagie]

I've got an anecdote that says that they don't.

If I'm looking at a certain color of green illumination and then cover one eye then the other, my perception of that color shifts slightly. It's still green, but with one eye it is "brighter" than the other eye.

[rootusrootus]

yep, this is the sort of question I pose to my kids. “How can you know that what you see as blue is not what I see as red?”

[VadimPR]

I find that fascinating as well! I hope tech will give us the answer in our lifetimes.