Awesome post and thought provoking topic. I really like that wood photograph you used to illustrate color constancy.
I've read that our brains can essentially hallucinate certain details of images or environments given the correct set of variables changing or taking place in a moment faster than our brains can process. I think there's some "stare at the black dot" experiments in existence that show how it works.
I find that intriguing, it makes sense when our reality is a construct of imagery that our brains must keep composed to a certain degree for reality to remain real...
Maybe that is why colors, sounds, and emotions tend to blend together during tripping. It's a strange feeling seeing the entire room take on either a darker or brighter hue suddenly that the mind somehow picks up on during the altered state, but otherwise would never really cognitively notice the change in hues.
There are a lot of interesting (and weird) cognitive "hallucinations" or illusions. Psychologists are interested in these illusions because they can use them as a way to investigate and understand the nature of our brain cognition and perception. There are a bunch of wild ones. One of my favourite one is the blind spot. We basically have a bundle of nerves going from our eyes to the brain. The area where these nerves exit is called the blind spot because we cannot see in that region. However, our brains trick us and hides the blind spots from us. Tricky brain! Check this video out to find your blind spot