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Friday, July 28, 2006
On Being Color Blind
Posted by Lance
In the back of my high school Biology book had a big circle with many smaller circles and I clearly made out the word "color". That was easy I thought until I read the captionIf you see the word "onion" you have normal color vision. If you the word "color" you are red-green color blind.Being color blind is like living in flatland. You miss a dimension and never notice until someone points it out to you. I grew up making the occasional color mistake but just believing everybody saw green and brown as different shades of the same color.I have had more official tests that show me fully red-green color blind. I don't see the world in black and white; I don't even have trouble distinguishing red and green. I do see certain color pairs as different shades of the same color: green-brown, blue-purple, red-pink and yellow-orange.
As an undergrad I took a course in computer graphics and they did a demonstration where they showed a colorful picture and then showed three variations where they would turn off one color in each. The instructor said that the original and one of the variations would look the same to a red-green color blind person. Everyone laughed but I went up closely and couldn't tell the two apart.
One day shopping with my wife, she held up two shirts and asked me which one I liked better. They looked identical to me. I claimed she was playing games with me. Now with my knowledge of interactive proofs, I could have tested her: Mix up the shirts behind my back and make her tell me which was which.
My father-in-law is also red-green color blind which means my daughters had a 50% chance of being color blind, a rarity for females. We've tested them and neither is color blind, at least not to the extent that I am.
While color blindness has no cure or fix, it is one of the easiest disabilities to live with. My wife and daughters make sure my clothes match. I have trouble when people give color-coded talks but that doesn't happen often in theoretical computer science. I try to keep colors simple on my own talks and webpages. The Red-Green 3-D glasses don't work for me at all, though the newer polarized 3-D glasses work just fine. I don't usually have trouble at traffic lights but I do have trouble telling blinking red from blinking yellow. If I can't tell from context I just stop, sometimes to the chagrin of the car behind me.
But when I look at art or nature I see one less dimension of colors than most everyone else. I will never know what I am missing.
8:03 AM
# 18 comments
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Many mammals have dichromatic vision with red-green color blindness. The only ones that are trichomatic (with the possible exception of Australian marsupials) are African primates.
At the other end, many birds are tetrachromatic; some are even pentachromatic. In addition to have having four (maybe five?) cone types, some birds have retinal oils that provide additoinal filters. Even when two birds are equally tetrachromatic, they may have different color response curves. That is, they may be different projections from the infinite-dimensional space of all "visible" light to R^4. Indeed, "visible" must be put in quotes because the total spectral range differs among species as well.
Unlike birds, mammals have fairly uniform color vision, either dichromatic or trichromatic, with color responses in about the same places in the spectrum.
So even if you can't know what you are missing because you are red-green colorblind, everyone should understand the wider context in which we are all "colorblind". We are all missing mountains of spectral information.
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This site contains a color blindness simulator that you can run on web pages or images to see what they look like to a colorblind person. I think it is quite revealing.
Varsha
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So the background of your blog is brown or green :)
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Another two remarks about biology and personal experience. The red-green splitting is biologically subtle in a way. The response curves for red and green overlap substantially. On the other hand, the blue response curve is almost disjoint from the green curve, and only intersects with the second peak of the red curve in the violet range.
At the level of retina cells, only a tiny fraction of cones are blue receptors; most of them are, I think, 2/3 red and 1/3 green. The blue cones are also not uniformly distributed. There are so few blue cones that blue should be dimmer than the other two colors, but blue perception is amplified by the brain.
Nonetheless, culturally and perhaps cognitively, blue and green are more similar than the other two pairs. At least, this is so for me and for my son, who I just asked. To me, green and brown are as vividly different as blue and brown are.
Well, the brain does so much mental reprocessing that in the end, you aren't missing all that much. Keeping colors simple is a good idea even for most people who aren't colorblind! There ought to be a Strunk and White for diagrams and web page design, not just for prose.
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This post was very timely. In today's Matlock episode, Matlock saves the day when the color blink murderer accidentally took the victim�s red scarf instead his own green scarf (The scarves were identical because they both received them that day at their 30 year Harvard Law School reunion.) Matlock even did an in court interactive proof with the two scarves so prove the color blindness of the alleged murderer. Just thought you all would like to know.
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Some women are tetrachromatic, kind of.
If large numbers of drivers can't tell blinking red from blinking yellow, maybe the system should be changed or augmented.
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Now that explains the weird color combination in your website's icon (the "favicon" file)!
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Since color blindness ia a condition limited to the functioning of the eye, (or so I gather from the comments) wouldn't it be conceivably possible some day to stimulate a certain part of a color blind person's brain, causing them to 'perceive' colors they had not before? The brain might have difficulty at first, but it seems that eventually a person could 'know what they were missing', even if they continued not to perceive it in their daily life. Yes?
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I'm color blind too ... but hey it kept me out of the military so I now thing of it as a blessing. Of course it does allow my wife to have some fun every once and a while ... which is why I don't even talk about her clothing.
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Being color blind can have advantages, too.
As an undergraduate I was taking part in a physics lab where we were analysing the spectrum of some gas I don't remember. The instructor came to look at our results and said: "Hey, you are missing the first line of the spectrum." Apparently there was a line which was very red, so red that I couldn't see it at all. From my perspective it was infra-red. A fellow student had to measure it which was somehow embarassing.
He went on measuring the remaining lines and I noted down the values. Finally he said "That's all" but I said "What about this last violet line?" Apparently nobody but me was able to see this line, it was just too violet -- ultraviolet. Of course nobody ever believed me although there were many more lines outside the visible spectrum.
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While color blindness has no cure or fix, it is one of the easiest disabilities to live with. My wife and daughters make sure my clothes match.
Even if you were not colorblind, as a computer scientist, this would still be a necessity.
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I never had trouble with red/yellow/green traffic light distinctions. The real trouble for me driving is that a red light is a somewhat dark blah color even at night, whereas my friends tell me it's more like an intense beacon. At night, the green lights are very close to the color of most street lights, so they don't stand out. When the green goes yellow, it can be a surprise since I didn't perceive there was a traffic signal that might change.
Another issue is blood. To me, it's again a very dark color, trending towards almost blackish when in a donation bag. I'm told it's a bright intense color, but not too me.
My wife's wedding ring is ruby, not diamond, and sometime I joke to her it could almost be anthracite coal to me.
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i am color blind too. and i was wondering if there was a web site with jobs that color blinds can not qualifies like, police officer, pilot ect...?
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I found out at age ten i was red/green colour blind. I had the same experiences you had except i tend to be very stubborn and sometimes would almost convince the other person they were wrong on a shade of colour!
I would also get the odd mocking from people that do not understand. It is difficult at times during presentations when the designer clearly hasn't taken into consideration colour blindness.
There is also alot of misconceptions and ignorance...i was treated like a leper by the school nurse...she was in disbelief that i could not read the numbers...i thought they were playing a prank! I also got a nice note home to my parents warning what jobs i could not do to which they ripped up.
I feel a bit of a freak and even though apparently its very common in men...i have yet to meet a single person with red/green colour blindness :-(
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Hey my name is william and i know how you feel. I am 13 and it seems right now is the hardest time of my life. I to am red-green color blind, I hate telling people that because their always like whats this color and they honestly think I see in black and white. My older brother is also red green color blind. We are the only two people in our family that want to fly jets but we cant it really sucks and i know how you feel.
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I'm also red-green color blind, but I usually don't tell any one since they usually start to treat you differently; but I have learned to live with it, and now I am a computer graphics expert, even though sometimes some of my animated characters look like aliens due to the incorrect skin color.
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I am monochromatic, I only see in black and white so my whole life is like an old episode of 'I love Lucy'. As I've never seen any colour, I've never really put much thought into it but I often wonder who seeing colour (or not) affects all aspects of life and emotion.
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your daughters are lucky. My dad is colorblind, so is his dad, and so is my mothers father. and so am I. As a female, it sometimes seems extra difficult as girls are supposed to be good at matching, decorating, etc. After 21 years, I still wear the same makeup every day so I know that it looks fine. I have to go shopping with a friend or just hope the clothing will be labeled. It's beyond frustrating.
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