SamKR wrote:Experience of a color and the corresponding wavelength are not the same thing, although in our experience these are usually correlated and consistent, and this is a very important point to understand. There can be perception of color even without "physical" light.
A few cases that are interesting to consider along these lines: a color blind person demonstrably has a different experience of a sight even though the same wavelengths are present.
In terms of perceptions, sometimes people who are not color blind can see the same thing and one person might say "that's blue" while another person says "that's purple" and a third person says "it's a blueish purple". Even if they are having the same visual experience, which isn't something that can be compared to know, they are at least using labels based on different aspects of that experience with different emphasis. Similarly, some people have a large color vocabulary while others have a small color vocabulary. Those with a small vocabulary would use a single label for a range of various shades that a person with a larger vocabulary might distinguish by name.
Regarding the perception of color without "physical" light, dreams and phosphenes
are both worth considering.