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Seeing colors differenty.

  1. Oct 28, 2004 #1
    This is something I thought of when I was a little kid, but I know I'm not the only one who's thought of this. Perhaps people here know the answer. I didn't know where to post, I guessed it could have belonged in Biology, but this has to do with beauty, as colors are very important to me and I'm sure others.

    Everyone sees their colors differently. What looks like green to me may look like purple to you. If you saw what I am seeing it would look like a Dr. Seuss world. We would call them the same things, and label them the same, and compare them the same "yeah it's yellow, like the color of the sun," because we all receive the same wavelengths of light and have the same labels for them.

    It's just like taste. I know things must actually taste different to different people, based on taste bud layout or what not. I know this because if a pea even so much as touches my tongue, it automatically effects a gag reflex. People who wolf down thier peas can't have the same perception.

    I know people have the same red/green/blue receptive cones in their retina and get the same light. I believe the difference is in the image the brain fabricates based on this input. A picture of the visible part of the spectrum or rainbow would still look like smooth transitions between violet and red for everyone, it would just look different.
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  3. Oct 28, 2004 #2
    If you're interested in the ramifications of these considerations in the philosophy of mind, please research the "inverted spectrum argument".
  4. Oct 30, 2004 #3
    I can't be sure of this, but I read somewhere that trying to determine whether or not our internal color experiences are the same will never be achieved with science. However, we can eliminate certain color differences, e.g. that you seeing red while I see purple is impossible.
  5. Oct 31, 2004 #4


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    Do you have any evidence on which to base that assertion? What reason do you have for believing that different people's eyes work differently?: they are all biologically the same.
  6. Oct 31, 2004 #5
    I don't think this was intended as a claim about the eyes (though I could be wrong). I think the author's intention was to point out that, hypothetically, it could be the case that although the physiology our respective visual systems may be the same, the phenomenological character of our experiences differ. In other words, it could be the case that given all the physical facts about our visual systems, it doesn't follow that if two people's visual systems are physically identical the phenomenological character of their experiences will also be identical. Thus construed, this is an attack against physicalism, and it is commonly referred to as the "inverted spectrum argument".
  7. Oct 31, 2004 #6


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    That's what I figured - but its hard to support such a thing scientifically, lol.
  8. Nov 3, 2004 #7
    I think the real question about colors is: are they real? Is grass really green, is the sky really blue, is that apple really red? We know that the perception of color gives us information about reality, but the "quality" aspect of color perception is really difficult to understand. What I mean is, there is no more difference between two different colors than there is between two notes in a musical instrument. So when we hear the seven octaves of a piano we perceive all sounds as being alike; if we experienced sound the way we experience color, a piano could sound as several different instruments depending on which key was pressed. That is odd and hard to understand.

    My impression, and I may be wrong, is that color is not real to the extent that we perceive it. If we perceived color correctly, we would not perceive a difference in quality between two different colors, only a difference in "quantity", "height", "pitch", or whatever word conveys the idea of variable quantity and same essential quality. The reason we perceive color the way we do is because our eyes actually perceive the same stimulus through different channels (the various kinds of color receptors in the eye). So we experience every color as a "mix", when in reality there is no mix, at least in the case of pure colors.

    So to answer the original question, I'd say most of us experience the same colors in slightly different ways, but only slightly. I think it's impossible for two people to experience the same color in completely different ways and still manage to agree on the meaning of the words they use to describe their experiences of color. Taken in isolation, it seems possible that someone might see red where we see blue, but I suspect it's impossible for two people to experience colors that way and still agree that "blue and yellow makes green", or that "black light cannot exist".

    Any thoughts?
  9. Nov 5, 2004 #8
    havent they proved this by using other peoples eyes as kinda 'mini-cameras' ? and recorded what they saw?
  10. Nov 5, 2004 #9
    In the ear the different frequencies are also separated and going into the brain via separate "channels", but it may have to do something the fact that there are far more channels in the ear than in the eye. Also the perceived color depends in very complicated (as yet mostly unknow) ways on the wavelengths coming from different parts of the scene, I mean the color of an apple whithn the scene does not only depend on the wavelengths of the light that is reflected by the apple but also on the wavelengths of the light coming from other parts of the scene.

    I do not see why that would be a problem, if we experience the incoming signals different we wil still talk about red and yellow and we will still learn to call the color that is a mixture of red and yellow green (even though is "feels" different to us). The exact way is "feels" does not matter as long as they are differnet, we can of course notice when someone cannot tell the difference between two colors.
  11. Nov 7, 2004 #10
    To understand my argument you have to think in the abstract. The problem is that most colors can be both a mixture of other colors as well as a color on their own. For instance, green exists as a pure color, but it can also be made up by mixing blue + yellow. So we have a situation just like numbers (which is what colors are, so physics tells us)

    Now imagine the following: can someone "experience" "six" the way we experience "four"? In principle it might seem possible; show the person four objects, they'll see six, but they think the correct word to describe that quantity is "four". That's exactly the argument for the inverted spectrum problem, isn't it?

    There's only one problem: someone who experiences "six" the way we experience "four" will soon find that he can't agree, for instance, that "six is greater than five", unless they also experience "five" in a different way. But the discrepancy shows itself again: "five is greater than four".

    The important fact is, you can't change the meaning of a single word without changing the meaning of thousands of other words, and still be able to agree with others. I suspect it might be possible, in principle, that two people may experience the world in completely opposite ways, but anything less than "completely opposite" will definitely show up in communication. In the particular case of color, "completely opposite" also means confusing black with white - something quite unlikely not to show up in communication.
  12. Nov 7, 2004 #11


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    You need to study up on the way that our eyes subset the world of light frequencies and turn the subsets into nerve signals, and how our visual cortex then begins to map these signals into perceived colors. Much of this (in the v.c.) is numeric, but it's quantities rather than integers. In any case just trying to imagine the process from first principles, as if there were no hard research available, is not going to get you close to the truth.
    Last edited: Nov 7, 2004
  13. Nov 7, 2004 #12
    Colors and the "eye"


    A set of interesting calculations suggests that a photon at 765 nm (far red) has just enough energy to cause the intermediate state in the cis to trans isomerization, thus setting the red end of the spectrum. The blue/violet end of the spectrum is near 350 nm. Photons more energetic than this could actually cause a bond to break rather than isomerize, thus setting the blue end of the spectrum.

    This link provides some very interesting information. What the human eye takes in and records, seems to come down to, how the Rhodopsin molecule interprets single photons. As you can see by the quote above, it does not interpret them the same. So are human Rhodopsin molecules isomorphic in all humans?, they could be but even if they were, the same response is not always given by the same stimuli. Why does a Rhodopsin molecule not always interpret the energy of a photon in the same way? Any comments?

    So it seems, that although humans should and could see the same colors, they vary slightly.
  14. Nov 8, 2004 #13
    Ludwig, your number example does not change anything, there simply is no reason that green feels like green and not like blue (no matter how this depends on wavelengths or whatever)... so if these feellings where reversed in someone else there would be no way to tell (the other would assign the same terms, green and blue, to different feelings than you would).
  15. Nov 8, 2004 #14


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    Psychometricians do studies on people who, because they have lesions in the brain, have scrambled "wiring", and see things differently from others. Colors are not AFAIK part of this but shapes and visual fields certainly are, and synesthesia. So there is some empirical evidence for different processing. Perhaps some day (this whole thread is speculation, right?) they will be able to pin down the part of the brain that actually assigns the color qualia; then we will know the answer to your question for sure.
  16. Nov 8, 2004 #15
    Exactly how can you be so sure about that?

    I do not say it's not possible, I say it's not as simple as people try to make it. It's not just a matter of replacing every usage of the word 'blue' with the word 'green'. If that were the case, how would you know that green and blue are not the same color?

    Another fallacy behind this inverted-spectrum argument is the idea that there are only a few colors (seven?). The fact is that the human eye is capable of perceiving more than a million colors, even if we don't have names for all of them. So "blue" is not a color, it's a category. If you say someone can experience "blue" as "green", the natural question would be "which blue and which green"?
  17. Nov 8, 2004 #16
    Could you sound a little bit less patronizing, please?

    You are one of those who believe neuroscience will one day reveal all that goes on inside a person's mind. I'm one of those who pay more attention to the fact that, to this day, neuroscience has not revealed a single clue as to what the mind is, let alone describe what's inside it. All they do is take pictures of brains and say things like "when someone is sexually aroused this portion of their brain tends to light up". Which is an insightful as saying "when someone is confused they tend to scratch their heads".

    I don't see where all that knowledge of meaningless trivia will lead us, but perhaps I need to "study up" a bit as you suggested...
  18. Nov 8, 2004 #17
    I am so sure about it because it is not an empirical question, it is a logical question. Let's assume that people can see a million colors, now it could be the case that the way color 1 feels to you is how color 2 feels to me:
    your color 1 = my color 2
    your color 2 = my color 3
    your color 3 = my color 4
    your color 1000000 = my color 1

    It is simply impossible to come up with an experiment that could tell.
    I do not think people make it simple, people just say "nobody knows"...

    Psychophysics studies can show that some people cannot do certain things and must be missing something, but they cannot show how people are experiencing things, this is why that has been called "the hard problem". The inverted spectrum thought experiment is just a nice story to illustrate the problem. Knowing which part of the brain is involved in experiencing the color will still not solve the problem. You would have to know how the brain assigns qualia, which requires being able to measure qualia or at least in some way knowing what qaulia a person is experiencing at some moment, that is "the hard problem".
  19. Dec 2, 2004 #18


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    We all see the same color

    The original question was "how do we or can we tell if everyone sees the same colors or see's them differently." We all see the same color simply because colors are not contingent on humans, because of this we can logically assume we all see the same colors because with out man the colors will still exist the same as if we did exist.
  20. Dec 2, 2004 #19


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    Since its back from the dead:
    Yes, we understand that, but the point is that light isn't that simple: besides having to swap colors, you also would have to swap intensities in a highly precise manner, as our sensitivities vary with frequency and the light generated by lights and the sun varies in intensity with frequency.

    Just swapping colors, regadless of how many, would not necessarily enable two people to pass a color-blindness test, for example - those tests test sensitivity.
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