Gosh, without even going deep into scientific articles and monographs, just recall how many times different people have referred differently to the color of something you wear. I have a jacket who some perceive as black and some as dark blue. I have another jacket that some perceive as grey and some as green. I have a blazer that some perceive as brownish and some as grey. Furthermore, some people are fucking achromates. What scientific proof do you need now?