Hmm, but my understanding is that humans who are natural tetrachromats see more colors in the yellow-red part of the spectrum
There is genetic evidence that some people might be natural tetrachromats, though as far as I know only one case has been confirmed, sort of. If this is true these people would have an additional Q type cone cell, with responsivity in the visible spectrum (so they don’t see UV). The mean responsivity of Q cells is in between M and L cells with heavy overlaps, so many of these new color qualia are also inaccessible.
And humans already can see UV light a little, but the thing that stops this from being visible is actually the lens, which blocks UV light normally to protect our eyes
UV-A is not stopped by the lens and can reach the retina.
There is genetic evidence that some people might be natural tetrachromats, though as far as I know only one case has been confirmed, sort of. If this is true these people would have an additional Q type cone cell, with responsivity in the visible spectrum (so they don’t see UV). The mean responsivity of Q cells is in between M and L cells with heavy overlaps, so many of these new color qualia are also inaccessible.
UV-A is not stopped by the lens and can reach the retina.