the second one is totally clear for me. True story.In April of 2001, while discussing with a close friend of mine Nick Yee, who is red-green colorblind, the differences in our subjective visual experiences, we realized that color vision is not an unequivocal gain. That is, in some situations, he could perceive variations in luminosity that I could not. This difference got us to thinking whether we could design a "reverse" color blindness test - one that he could pass because he is color blind, and one that I would fail because I am not.
I like reverse tests way better, 'cos that way I'm winning, like.