Color and the Brain
(April 5, 2002)

NOTE: See "Concepts, Introspection, and Phenomenal Consciousness: An Information-Theoretic Account". NOTE: See "Qualia"

Colors are a figment of the mind. Color theory gives us an understanding of the cones and rods of the eye, the principle of tristimulus. Physics gives us the description of light as electromagnetic energy of varying intensity in different wavelengths.

We can think of light as being progressively "de-realized" as it passes through space into our eyes. Light begins as rays impinging on our eyes. Our eyes take "measurements" of light and ... Before light "reaches" the brain, it has a reversible description--that is, we can take it apart and put it back together (e.g., know spectra, roughly, from response of rods, cones, etc.). But in the brain light loses its reversibility. ...

As an example, let's look at what goes on when we try to relate our perception of color to others. Start with something easy--a ... If we say "". We could take a measurement of the electromagnetic spectra reflected by this object. But in both of these cases, we're merely using a referential means of communication. We haven't externalized that intangible concept of color that ...

Means of quantizing color

How can we talk about color? We can compare it to other sensations, talk about what it reminds us of, ... But neither of these modes of communication hold any information about one's internal "grasp" of color.

If we try to relate color in terms of non-color sensations, we're still using comparisons to things that co-occur with a particular color. For instance, relating the sensation of "red-orange" as a "sunset" relies on evoking the colors viewed by another at sunset...

Interpretation

What does all of this mean? For one thing, it reveals the insufficiency of speech and even physical measurements to communicate the conception of a particular color that we hold in our minds. There is absolutely no way that one person's internal notion of color can be externalized. Yet the fact remains that "red" is most certainly a very real and tangible thing for all of us. The act of relating one's own perception of "red" will leave one with a feeling of having reached but not grasped... It is *impossible* to communicate the internal sensation of any color.

Let's say that you disagree--you argue that your sense of a particular color can be communicated. Then try and communicate your sense of any color to someone else. Try and convince them that the red they see is identical to the red you see.

Extension to other senses

We can extend this inability to express internal sensations to other senses--taste, hearing, scent, touch (however, for some reason, touch seems to be the most reversibly expressible of these senses--it's a straightforward system of analysing moisture, texture, and temperature over short periods of time). For example, try expressing a "bitter" taste to someone *without* using a comparison to other bitter substances. It seems that the more intimately tied to the brain a sense is, the more difficult it is to express the internal nature of that sense (I'm stretching it here with a rough definition of "intimately tied"). In order of ease of expression, the senses are: touch, sound, smell/taste, sight. We can further break down each sense in terms of the nature of the physical quantity measured (mechanical, physical, electromagnetic).

If we take another leap and characterize mechanical, chemical, and electromagnetic quantities in terms of degree of complexity... In the following, please disregard the fact that I'm getting into the murky waters of personifying the notion of "complexity" in terms of heuristics. Mechanical phenomena are the simplest to describe--fields of vectors, tensors, etc. Chemical phenomena ... Electromagnetic quantities involve the paradox of the wave-particle duality of EM radiation.