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Medical Color perception

  1. Sep 14, 2005 #1
    I like some colors and you may be some other. But is it possible that you and me are liking the same colors, but have different names fot it.
    The wavlength that produces a sensation of red color in my brain, is producing the sensation of green color in yours and that which produces red in you, seems to me being blue. So, when I say I like red, you think its green and you do not like it. And when you say you like blue, I may not like it.
    But , actually we both are liking the same wavelength.
    We are not able to make out the difference because since childhood, we have perceived these colors with different names.
    What the logic behind this difference in color perception, or I must say wavelength perception ?
     
  2. jcsd
  3. Sep 14, 2005 #2
    I have a hard time believing these two pictures can equally be seen as beautiful:
     

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  4. Sep 14, 2005 #3

    EnumaElish

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    Is the picture on the right close to the visual perception by a color blind person?
     
  5. Sep 14, 2005 #4
    No, I just took a graphics editor and swapped some colors. But your question itself is interesting enough: we perceive the left picture as being more colorful than the right one, but if you look closely, even the left picture doesn't have a lot of different colors, it's mostly shades of red.

    A color-blind person probably sees something like one of these, depending on which color the person is blind to (red, green, and blue, respectively)
     

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  6. Sep 14, 2005 #5

    EnumaElish

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    AFAIK color blind persons aren't allowed to drive. So they must be unable to tell red from yellow, or yellow from green, or red from green (or all of these). But I am not sure which.

    P.S. I found this link; apparently there are different types of color blindness (blindness of different colors).
     
    Last edited: Sep 14, 2005
  7. Sep 14, 2005 #6
    I don't think so, at least not where I live. Color-blind people are fully functional. You don't have trouble watching black-and-white movies, do you?

    Actually, most of the time they can tell colors pretty well. Traffic lights, for instance, look different to them, although perhaps not as different as to us.

    Some people cannot see color, some people cannot see certain colors. Each one of us perceives color in slightly different ways, and even our own perception changes with age. If you're really interested in the subject, check this link: http://www.firelily.com/opinions/color.html
     
  8. Sep 23, 2005 #7

    HallsofIvy

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    The question, as I see it, is: if two people look at a color they have both learned to call "red", do they necessarily see the same thing?

    The answer is "yes and know- it depends on what you mean by 'the same thing'".

    I know that when I look at something with my left eye closed, it is a slightly different color than if I look at it with my right eye closed. And with both eyes open it appears to be an "average". So I feel sure that other people would not see exactly the same colors I do. However, since certain properties of what we call colors (frequency, wavelength) are objective, I also feel sure that the differences will be very minor- we may see different shades of red, but the other person will not be seeing what I would call "blue"!
     
  9. Sep 24, 2005 #8
    I don't experience this at all, and can't recall ever having read of any accounts of a similar report. I think it's very unusual.
     
  10. Sep 24, 2005 #9

    Moonbear

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    They don't have to see the colors. Traffic lights always have red on top and green on the bottom, so all they need to watch for is which of the lights is lit, even if they see them all as some shade of brown.

    As for the original question, I don't think it's an answerable question. There just isn't a way to test it and find out what someone else is seeing when they look at the same thing as you look at.
     
  11. Sep 24, 2005 #10
    Irrelevant for the perception discussion, I know, but I don't think they could tell if the light is on top or bottom of the traffic light if it's dark (and the light isn't changing).
     
  12. Sep 24, 2005 #11
    Something I just found in the link posted by Johann:

    "...diseases can also affect color vision. Of the two other people I mentioned in the usability test example, one was a male dichromat, the other was a woman with glaucoma. She has a non-acute form of glaucoma, and had some permanent damage occur before the condition was detected and treatment begun. Among other things, she now has different color perception in each eye. Yes, she finds this to be extremely distracting at times."

    Firelily Designs - Color Vision, Color Deficiency
    Address:http://www.firelily.com/opinions/color.html
     
  13. Sep 24, 2005 #12

    Moonbear

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    You can see light, the colors just aren't distinguishable.

    http://www.toledo-bend.com/colorblind/aboutCB.html
     
  14. Sep 24, 2005 #13

    selfAdjoint

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    They've just installed some lights near me that are going to give color-blind people trouble. They are in the form of a panel with two arrows, an "up" for straight ahead, and a "left" for left turns. These arrows glow successively red, amber, and green and there's no positional clue for those who have trouble distinguishing any of those colors from each others.
     
  15. Sep 24, 2005 #14

    EnumaElish

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    What about emotions associated with colors though? (Red = danger, green = peace, orange/yellow = visibility?) Does a color-blind person react to a red light (traffic light or brake light) in the same way as a color seeing person?
     
  16. Sep 24, 2005 #15
    Yes, it looks from all these links like most people with color blindness have red-green problems. The link posted by Johann, though, mentions that the effects are different depending on if it's filtered light, generated light, or reflected light. There are at least four different kinds of red-green problems, as well, each with it's own difficulties.
     
  17. Sep 24, 2005 #16
    Here's the standard test:

    Ishihara Test for Color Blindness
    Address:http://www.toledo-bend.com/colorblind/Ishihara.html

    I wonder to what extent there are fine degrees of color blindness. It seems the anomalous trichromatic version of it would allow for many fine shadings of colorbindness, as well as a kind of maximally developed color vision.
     
  18. Sep 25, 2005 #17

    Moonbear

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    Emotions associated with color? You learn that red means stop. I would suppose a color-blind person instead learns that a big octagon with the word STOP means stop. There is nothing inherently special about the choices of red, green and yellow to signify stop, go and slow down. In Chinese culture, red symbolizes happiness or good fortune, so just by this one example you can see that the significance of a color is learned.
     
  19. Sep 25, 2005 #18

    Moonbear

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    That's going to be quite problematic! I've also seen an increase in lights with the left arrow turning from green to red rather than green to off (when the straight-ahead traffic has the green light, you're not supposed to be making left turns, even if you see a break in oncoming traffic...I don't see why this is a necessary signal, but they have them and clearly a color blind person is going to have trouble with it). Then again, I've also come across lights that nobody can see...they put them up with some sort of arrow display thing that doesn't show up until you're under it when there's a bright sun glare, and of course the worst sun glare is during rush hour traffic. Someone isn't thinking too well when they're designing new traffic lights.

    The ones with the better design I've only rarely seen over the years...they have "GO" and "STOP" in black letters over the light, so if you can't see the color, you can see the words.
     
  20. Sep 25, 2005 #19

    EnumaElish

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    Really? Blood is red, it can't possibly mean happiness except for Lord Dracula (or his brides)? Trees are green and they are peaceful. Orange and yellow are the most highly visible colors to the human eye; that's why traffic vests are usually either color. Red stands out like a bloody finger on almost any background, so it is "meant" to be visible, too. Wildlife prefers red, orange and yellow to signal "danger" even in imitation.
     
  21. Sep 25, 2005 #20

    Moonbear

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    Actually, green and red are fairly equally seen, and in low light conditions, green is more easily seen than red. Courtesy of the link Hitssquad posted in the other Colors thread:

    http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.html#c3b

    If you're associating some emotive value to certain colors, it's not universal.

    Wildlife don't "prefer" red because it has some inherent value as a danger signal, red is just effective in that function because it contrasts against their predominantly green surroundings.

    Traffic vests stand out because of the shade of orange or yellow chosen. If they were all lemon yellow, they wouldn't stand out very well at all.
     
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