Godot

How do we know that the colour I see as blue is the same colour you see when looking at the identical object? Apart from the obvious answers of physiological construction of the eye or of spectral waveform lengths (or even colourblindness if you're being a smartass), can we be certain that our perception of the world is identical?
For all I know, we may agree that a particular object is blue, but the actual colour I represent as blue is orange in your mind.

Any thoughts?

Jinto

I'd give you some, but I don't know if my perception of thinking is the same as your perception of thinking, I can't provide any meaningful answer to your question.

Neilium

After working in graphic arts and publishing for 15 years, I can tell you color is subjective; no two people see color the same way. It's also relative: you can adjust the ambient light so that a blue wall appears pink (if the viewer can not see anything else.) But if you place a few other colors on that wall, all of the sudden the wall is blue again.

But, apart from the colorblind, everyone agrees on blue things being blue. We argue about the shade of blue, but it's still blue.

Healthy human eyes are pretty much alike from person to person. They all work the same and send roughly the same impulses to the visual cortex. At that point, it doesn't matter. I know you were looking for something other than physiological construction of the eye as proof, but I can't think of anything more conclusive.

-Neil

Warwick

I agree. Everyone can agree that something is "blue" based on wavelength, etc., but that may be perceived differently by your mind.

Along the same lines, are there colours that exist that we cannot see?

Neilium

Some flowers have pigments that reflect ultraviolet light, and apparently birds and insects respond to this, so they must see some sort of color where those pigments are placed.

Of course, this complicates things even further. We can only infer what colors an animal sees (and whether it can even distinguish colors) by observing it's behavior.

-Neil

Pyrrho

No. There are physiological aspects that can be examined. In the human eye, there are two types of photoreceptors: rods and cones. Rods are sensitive to very low levels of light, but not to color. Cones are sensitive to color, but are not sensitive to low levels of light. This is why, when it is so dark that you almost can't see, you only see in black and white. Furthermore, we have three kinds of cones, which are sensitive to different colors. Now, many animals have eyes similar to ours. For example, consider the dog:

http://www.uwsp.edu/psych/dog/LA/DrP4.htm

As dogs have fewer cones and more rods, their night vision is better (in a healthy dog, of course, as they can suffer from eye problems just like us). But since they have only two kinds of cones, we can know that they are not capable of seeing certain colors (see link above).

So we can know quite a bit about what an animal sees or does not see independently of observing its behaviour.

Neilium

Pyrrho,

I stand corrected.

-Neil

Pyrrho

Please read the corrected version of my post. I apologize for my previous error.

Tani

pyrrho:

neilium is still correct, you still have to infer, just not from a catagory we call "dogs" or generally "animals" but from the electro-behaviour of the cones and rods.

Neilium

Hi, again,

Let me throw something else in here: For this sort of disparity to happen, we would have to perceive color only after we see it; perceive the perception, if you can imagine that. It seems like an unneeded step.

But, without that extra step, the nerve impulses travel straight from the eyes to the visual cortex, and, assuming we're awake and fairly sober, we are conscious of what we are seeing. I don't think there's an editor in there that sorts out the blue from the orange and maybe confuses the two.

-neil