This is kind of an anecdotal aside, but colors and lighting have been on my brain of late as I'm having my bathroom remodeled. I really didn't think it would be a big deal but I'm having a really tough time coming up with the floor tile choice. My original pick got somehow delayed so I've been searching for a quick replacement at Home Depot/Lowes, etc - places that have stock right now.
How this relates is it's fascinating to me that I can look at the same piece of tile and depending on what I sit it on, what the lighting is, how far I stand, etc. it looks drastically different. I took 3 photos of it on the same surface with very slight differences and it looks like a different color in each shot. I was at the store earlier, and everything I looked at appeared very different depending on if I held it one way or another, or whether it was the "glamour" shot they had with multiple pieces and grouting. Then of course the lighting is always that harsh bright white which makes everything appear lighter.
Obviously this is not the same thing as what's going on with the dress, but I was just reminded how easily our own perceptions of color are tweaked when conditions (lighting, distance, contrast to other objects, etc) come into play. That makes it a little easier for me to understand how the manipulation of white balance on the dress photo can cause such a difference in what people perceive or think they see.
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Another interesting aside, when I showed my colleague the 3 side by side photos from one of the links you guys posted, he described the one on the right as blue/black, left as white/gold, and in the middle as white and gold in shadow - he didn't believe me when I told him it was the same image as the one he earlier was sure was blue/black.