You mean like. Colour receptors in their eyes? I think three (that is to say, ive never given it thought before).
I bet there's always that one clone in a facility with tetrachromacy though. And you'll be working on spectrometry or whatever, and the second they get the slightest excuse they'll go "Oh the reflected beam is such a lovely shade of squirple ๐" LIKE WE FUCKING GET IT ASSHOLE YOU CAN SEE A WHOLE NEW SIDE TO REALITY. SO WHAT ITS PRETTY IN INFRARED OR UV WHATEVER GIVE US A FUCKING BREAKKK

