> Becase when I see a mix of blue and green and there is only two buttons, I choose green. If you choose green, because you see a slight more tint of green than blue, yes, that's what you should do for this particular test. Just as you should choose blue if you see slightly more blue. For many when close to the middle hard to tell since have to go with your eyes and gut. But if anytime you are unsure if blue or green, if you always choose green regardless, then the test presumably wouldn't provide accurate results. > Or maybe I should treat the buttons as "> 0.5 green" and "> 0.5 blue". Yes, with each color they show, it's asking you if you see green (aka more green than blue) or blue (aka more blue than green). With the test starting off easier and then shades much closer to the middle (either left or right of the middle) where much harder to tell without a color picker, and everyone's eyes will be different and close to the middle you will probably see most as either blue or green.