Color constancy, if I understand correctly, is a product of some of our cells in our visual cortex applying a type of color processing algorithm to what we see, allowing us to distinguish the color of an object in various light conditions (e.g an orange is orange at night and during the day).
Of course that means our brain is lying to us, giving us a false impression of what we are actually seeing. This optical illusion illustrates the damnable liar our brain can be:
(both square A and B are actually identical to one another, despite what your pants on fire brain is telling you).
This brings to mind a couple of questions:
First, what would we actually see if these math genius cells responsible for calculating the color we actually perceive were not there, or where damaged? Is there any medical condition that could result in this phenomena? Is there some way to simulate what a green apple ACTUALLY looks like in different lighting - trick these cells somehow?
Could we re purpose these suckers so that I might ace my next math exam, or at least get really good at Photoshop?
More seriously, are there any other ways our brain lies to us? And are there metaphors or examples of the contrast between reality and what is perceived for these other “lies”?
You are using a strange mix of philosophical and scientific terms in your OP and they aren’t really compatible.
For instance:
Color perception is created by the brain so it is pointless to talk about what it ‘really’ looks like outside of that context. The entire mental picture only exists in the brain. It doesn’t matter what the individual inputs are registering for any given image because the image is created in the brain by incorporating many sources of data and adjusting them to fit within its own models. A green apple doesn’t ‘look’ like anything if someone isn’t there see it because the image is created by the brain and the most important part is that it is consistent from one green apple or another. Green doesn’t exist in nature either. It is just the brain’s interpretation of a particular wavelength of light and how it fits into its immediate context. The color could be shifted to something completely different without any issues as long as it is consistent.
There are lots of phenomena like this. Ones based on vision are called optical illusions and there are many good ones on the web such as:
Other sensory systems have their own sets of illusions. A good sensory sensation only exists as an interpretation of many data sources by the brain and there are plenty of ways to trick it.
One example that I can give you is camouflage. During WWII, aerial recon spotters were chosen from men who were color blind. They were less fooled by the similar colors of camouflage, since they couldn’t see some of the colors that were being imitated. They were then able to see how the camo didn’t match colors as well in the remaining spectra, or they focused more on shapes that didn’t fit in.
(In fact, color vision seems to come into and out of vogue among mammal species as well. For every species that finds it an advantage, like us, another species has dropped it.)
Anyway, from the more philosophical standpoint of what “should be”, I would say that the brain is NOT lying to us - it’s telling us the truth despite the facts. In the grey square illusion, I’d argue that the illusion is the “correct” appearance - letting the shadow make us think those squares are the same color would be less useful than the self-correcting mechanism in the brain.
They are “lies” strictly in terms of the shades of color used in the .jpg. With a real cylinder tho your eyes/brain would in fact be telling the truth, that in fact square A is indeed much darker than square B.
[Hope I didn’t just open a huge can of worms here…]
There are plenty of other lies that your brain tells you regarding vision. Mach bands, for instance, where your brain puts apparent discontinuities on objects when the gradients differ. Or the fact that the world looks stable to you despite the fact that your eyes constantly darting around (microsaccades).
Here’s another trick you can do. Look at your hands and clap them together. You see and feel them hit at the same time. Actually, you only think you do. It takes 200 milliseconds from the time the photons hit your retina until your visual cortex has fully decoded the image you’re viewing. It only takes 10 milliseconds, however, for you to feel them hitting. Your brain synchronizes the sensations, to let you know that they came from the same event.
So the brain assigns relative color values by taking into account the whole picture at once and the relation of each part to the whole. Instead of maintaining absolute values for hue and for value (brightness). I quite like how it does that, you know. I don’t know why, but I get the feeling that absolute-value color perception would fatigue one’s vision much more quickly than gestalt coloring does.
