What if what I see as red, you see as blue?

by metacognizant

Around my second year of college, I started pondering the question in this blog’s title: “What if what I see as red, you see as blue?” I wasn’t meaning a simple, color-blind category error, but a perceptual difference stemming from childhood. We’ve learned what to call specific colors by instruction from others; someone points at something red and says “this is red.” Once we learned what color red was, we could separate it from blue and the like. But there’s really no way to get outside our own heads and see if the color we call red is actually the color of what we’re looking at. In fact, I have no way of knowing if I got into your head, the perception that I call the color red wouldn’t be the perception that you call the color blue. This is not a problem for everyday life–we all refer to any given thing as red or whatever it is, because we’ve been taught that that given thing is red or whatever it is–but it’s a question that’s plagued me. I’ve annoyed many a college professor with this question whenever the question of knowing or our senses has been brought up. It can even be extended to things like, “What if the sensation I label as pain, you label as pleasure? If I felt what you feel when you say something doesn’t feel good, would I say that that’s what I feel when something does feel good?” These questions for me have prompted me to accept the philosophy of critical realism–there is a reality out there that’s conveyed accurately as it is by some sense-data, but other sense-data does not accurately convey reality as it is.

Turns out, there are good neuroscientific reasons to accept this philosophy. The eminent neuroscientist V. S. Ramachandran is known for his work on human perception. In his latest book, The Tell-Tale Brain, he has a very succinct description of how we’ve come to understand that people perceive reality on the basis of a variety of neuroscientific experiments. His description is this:

In order to understand perception, you need to first get rid of the notion that the image at the back of your eye simply gets “relayed” back to your brain to be displayed on a screen…. If the image on the retina is transmitted to the brain and “projected” on some internal mental screen, then you would need some sort of “little man”–a homunculus–inside your head looking at the image and interpreting or understanding it for you. But how would the homunculus be able to understand the images flashing by on his screen? There would have to be another, even smaller chap looking into his head–and so on. It is a situation of infinite regress of eyes, images, and little people, without really solving the problem of perception…. Instead, you must understand that as soon as the rays of light are converted into neural impulses at the back of your eye, it no longer makes sense to think of the visual information as being an image. We must think, instead, of symbolic descriptions that represent the scenes and objects that had been in the image. Say I wanted someone to know what the chair across the room from me looks like. I could take him there and point it out to him so he could see it for himself, but that isn’t a symbolic description. I could show him a photograph or a drawing of the chair, but that is still not symbolic because it bears a physical resemblance. But if I hand the person a written note describing the chair, we have crossed over into the realm of symbolic description: The squiggles of ink on the paper bear no physical resemblance to the chair; they merely symbolize it.

Analogously, the brain creates symbolic descriptions. It does not recreate the original image, but represents the various features and aspects of the image in totally new terms–not with squiggles of ink, of course, but in its own alphabet of nerve impulses. These symbolic encodings are created partly in your retina itself but mostly in your brain. Once there, they are parceled and transformed and combined in the extensive network of visual brain areas that eventually let you recognize objects. Of course, the vast majority of this processing goes on behind the scenes without entering your conscious awareness, which is why it feels effortless and obvious (pp.47-48).

Ramachandran goes on to illustrate this ingeniously with a few thought experiments and illustrations, but it has also been steadily confirmed by neuroscience at large. This might rattle your assurance about reality, and it should. Our perceptions are not as clear-cut as we might like to think; instead, they are our brain’s best guess as to how things really are–which brings us back to our first question: what if what I see as red, you see as blue?