PDA

View Full Version : Color perception

Dr. Strangemind
06-28-2002, 09:56 AM
I’ve often wondered if we all perceive colors the same; i.e. when I see what I call “red,” does everyone else see what I see, or does everyone perceive color differently?
How would we know?

Dr. Strangemind

Kamandi
06-28-2002, 11:49 AM
Well, all humans can sense the same spectrum of light (that is, nobody can see infra-red or ultraviolet light). Our eyes and brains are all built more or less the same. Since the spectrum can be separated with a prism and we can all agree on the name of each of the colors, I don't understand how we couldn't perceive colors the same way.

Then again, what about the colorblind?

Monty
06-28-2002, 02:16 PM
As a colourblind individual, I'll answer with an analogy:

Consider the numberline cotaining just whole numbers as follows

1 2 3 4 5 6 7 8 9

Now, everyone gets to see numbers 1 and 9 and they see either all or some of the numbers in between them.

Those who aren't colourblind see the entire line. Those of us who are partially colourblind will see the numbers 1 and 2 as 1, the numbers 3 and 4 as 3, etc. Those of us who are severely colourblind will see the numbers 1, 2, 3, and 4 all as the number 1, etc.

Essentially, it's a matter of how your eyes divide the spectrum.

andy_fl
06-28-2002, 02:48 PM
I don't understand how we couldn't perceive colors the same way

I have often wondered about this question a lot too and I understand what Kamandi is implying.

The color (like a lot of many things) is an representation in the mind and need not be consistent with different people. Let me explain why

Say you see a leaf when you are a kid and get a "certain representation of the color (Call it [B]Rep1[\B]" in your mind and you are told it is called green. Next you are told about red, blue etc. etc. and their you have your perception of color.

Say another kid sees the leaf and has a "certain representation of the color (Call it [B]Rep2[\B]" in his mind and is told it is green again, Now there is no way to know if [B]Rep1[\B] and [B]Rep2[\B] are the same.

That maybe if the visual centers of the two brains could be surgically removed and interchanged between two people, they may end up seeing green as blue or something else (OR MAYBE NOT - BUT I WONDER).

Its much like data and its encoding (internal representation). Two people maynot see the same. (?)

Monty
06-28-2002, 05:34 PM
Andy: Scroll up to the post before yours for a simpler explanation. :)

photopat
06-28-2002, 05:51 PM
I agree with andy. We may not all process colors exactly the same way, some people's perceptions may be different from others. As long as we all look at the same thing as define it as the same color though, it really doesn't matter.

To put it another way, let's say two people have their minds transferred into each other's brains. They discover that the brains function slightly differently in how they process colors and one person "sees" blue as red and vice versa. They would realize that the eyes and brains don't process the spectrum in the same way, but that they call the same physical sample by the same name.

octothorpe
06-28-2002, 06:09 PM
Hmmm...

It's a bit rough trying to wrap my mind around this whole thing.

On the one hand, it seems pretty straightforward, it is universally agreed that a certain color is, say, blue. Everybody who sees this color remarks that it is blue, so everybody must see the same thing.

But, are they actually seeing the same thing? I would think that for this to be possible, all eyes must be exactly alike. The same number of rods and cones in the same ratio. If the relationship were off (i.e. higher rod/cone ratio, higher red/green cone ratio, etc.) the eye would be skewed off the 'normal'. This doesn't mean that you'd be unable to see color, just that you'd see it 'differently'. You could take this to the point that you may lack one or more of the appropriate cones. If you didn't have, say, 'green' cones, you would still be able to see color, just nothing that had a green component. So, from that extreme, it seems reasonable to assume that there could be infinite subtle 'deficiencies' (for lack of a better term) that would result in you seeing colors in a slightly different way than someone else, or, for that matter, anybody else. If the differences are subtle enough, your color vision would still fall within the 'normal' category and you'd still agree that blue is blue.

It just seems to me that the eye alone (not even factoring in the optic nerve and brain) is so complex that no 2 can be alike and thus, no 2 people 'see' alike.

#

Achernar
06-28-2002, 06:50 PM
I've wondered this myself and concluded that we can never know, but I'm not so sure about that. There is something that we can all agree on. White is more "intense" than black. A white thing can hurt to look at, and a black thing won't. Not all colors are as clear-cut as black and white, but I think that we can conclude that, say, yellow is more "intense" than, say, blue, so it can't be totally different for everyone.

andy_fl
06-28-2002, 07:09 PM
Monty - Andy: Scroll up to the post before yours for a simpler explanation.

I think you did'nt get my point.

But I agree with photopat and Achenar that we may never know and does'nt really matter :) as long as the rules of color addition etc. remains the same.

06-28-2002, 07:24 PM
I would go so far as to say that most people percieve any given color differently than each other. People who are related to each other or come from similar backgrounds probably have a greater chance of seeing a given color the same. This is due to at least two effects: genetics, and culture.

First, genetics. You percieve any given color based upon the way that your brain interperets the signals set to it from your retina. These signals, in turn, are based upon the way that various nerves have self-arranged themselves filtering the signals sent to them by your eyes' rods and cones. These rods and cones send signals to these nerve cells based upon your genetics. Your blue cones' color perception comes from a gene on chromosome 7, and the red and green cones' color perceptions come from genes on your X chromosome. As men have only one copy of the X chromosome, this explains why far more men are red-green colorblind than women. I don't recall, offhand, where your rods' color comes from, but as your rods only affect your perception in low-light situations, when you don't have color vision, it's not important.

Second, culturally, some colors that are identical are different depending upon who you ask. The one that springs to mind immediately is the bottom light's color on traffic lights. While here in the US, the bottom light's color is green, in Japan, it's blue. This doesn't mean that the colors are actually different. A Japanese person in the US will call our lights blue, just as an American in Japan will call theirs green. The bottom light has components of both green and blue, and for American culture, the green component is more significant, while the blue component is more significant in Japanese culture.

There are many other cultural differences on colors, but they don't come to mind as readily as the traffic light example.

Genetics cite (http://www.hhmi.org/senses/b130.html)
Cultural cite #1(not terribly authorative, alas) (http://www.thejapanesepage.com/colors.htm)
Cultural cite #2 (ditto) (http://farstrider.net/Japan/DidYouKnow.htm)

Broomstick
06-28-2002, 07:40 PM
Speaking as one of the colorblind...

I know I don't see colors exactly as the majority does. For instance, while there are a lot of greens you and I will both agree are "green", there a LOT of colors you (the majority) would call green that I would call blue, brown, or yellow (blue-greens, khakis, yellow-greens, chartreuse, etc...)

And, as a side note, there are several varieties of colorblindness, some more of a problem than others. Mine is very mild.

So, even if the majority were to perceive colors the same, there's a significant minority who have differing perceptions.

Then there's the Norweigian expect on color vision who, himself, has never seen color having only monochromatic vision (an extremely rare variant, but they do have an on-line group now, as does just about every other obscure condition, disability, disease, or what have you)

Monty
06-28-2002, 07:45 PM
I got your point, andy. But you're a tad wrong. We don't all see the same colours. We see the same light. Big difference.

06-28-2002, 08:15 PM
Actually, andy_fl, a good deal of the color-processing is done right on the surface of the eye, on the retina. The brain is mostly used for reconstructing and segmenting the signals to present a coherent image to our mind. So, if eye transplants vaguely similar to those in That Movie Starring that Guy with the Face ever become possible, we would have more info to go on.

andy_fl
06-28-2002, 08:44 PM
Great Punoqllads. I'd certainly look forward to that.

And Monty - don't take it personal dude.

Monty
06-28-2002, 10:21 PM
I'm not taking it personally. I just like stuff to be correct.

Cheers!

Achernar
06-29-2002, 01:50 AM
Oooh, you know what would be weird? If everyone had the same favorite color. Like, my favorite color is green, and my friend's is blue, but what I think green looks like is what she thinks blue looks like. And in reality, what your favorite color is is not determined by what you like, but by which color looks to you like green looks to me. WEIRD!