In a normal XX woman, one of the X chromosomes in each cell is inactivated (well mostly inactivated; apparently part of it remains active) and crumples up into something called a “Barr body”. Which one is inactivated is random in each cell. One consequence that in a female carrier of RG color blindness, half of the red (or is green?) sensitive cones will be defective and I imagine that this can result in slightly anomalous color vision. The same phenomenon explains why approximately 2/3 of female new world monkeys but none of the males have 3 color vision since there are 3 color genes, two of which are on the X, but are alternates. So a female can have one of each (which get randomly expressed in the cones) while males only one or the other. Presumably, in old world monkeys and all apes (old world monkeys are more closely related to apes than to new world monkeys) that gene duplicated giving most of us true 3 color vision after the trait spread through selection. I wonder if the common RG color blindness is just what’s left over from that selection.
From what I’ve read it seems that in many cases there won’t be any obvious signs until puberty. Androgen insensitivity can be full or partial. In cases of full insensitivity, the external sexual characteristics will be female, although internally the uterus will be undeveloped and there will be male sex organs in the abdomen. Girls and women with full insensitivity will never menstruate. Partial insensitivity can lead to external sexual characteristics that are typically male, female, or a combination of both, and again, some of these characteristics won’t show up until puberty.
Color blindness is more common in males because the most common cause is a mutation of a gene on the X chromosome that controls the development of color vision. Females, with their two X chromosomes, are protected from this mutation - the gene would have to be defective in both X chromosomes for color blindness to happen. Males, with their single X chromosome, lack this redundancy. My thinking is that a female with androgen insensitivity syndrome would have only one X chromosome, and so would be as likely as a male to develop color blindness. It’s not likely, but it could happen.
I have trouble distinguishing browns and greens. They definitely do not look gray or black or anything like that. If it’s a bright green, I know it’s green. If it’s a brown without a lot of green, I can tell it’s brown.
The stuff in between all looks muddy green-brown. Since I know I’m colorblind, I’m aware that it’s probably some shade in between. Before I realized that, I guess I just thought that people were really fond of the particularly ugly shade of brown-green they all look like to me.
Well, we were all men, so the odds weren’t too unlikely. We did have to have a woman read it for us. She was amused.
Actually, it’s a bit of a bother: part of my job as chemist is to rate the appearance of our products… many of which are described as “amber”. What I think of as amber (brown-gold) is apparently only a limited subset of the “amber” possibilities.
Operations really likes that feature, though, since if they ask me about an odd appearance: “Looks amber to me!” “Okay, ship it!”
I didn’t know until after he had passed away that my father had a problem with some colors. I wish I could have asked him about it. Maybe he wouldn’t have said anything anyway, he kept quiet about a lot of subjects. My mother tells me everything green look gray to him, but she may not have gotten the details either. Someone else I knew for a little while had blue-yellow blindness, and it seemed strange to me at the time that she said yellow and gray were her favorite colors (of course it’s just called blue yellow, she must have had either tritanopia or tritanomaly). Because she married someone I knew and then divorced him soon afterwards I never could ask her anything about it. Interesting that you mention brown which is a mix of colors. Ever since realizing the possibility that I may not be perceiving the color blue well, the whole topic of color blindness has become more interesting.
What is meant by “defective”? They don’t burn out or disappear, or acuity would be greatly damaged. With say, a deutan, their M cones are “replaced” by L cones. Same idea?
Also (and sorry if I cover something you already did), it is a common shorthand to give cones by their peak sensitivities, e.g. S = 420, M = 540; L = 560. But in reality, this is just a convention. Polymorphisms are present in humans, just like in monkeys, so that L cone could be 560, 559, 561, etc. depending on what gene you get from parent(s). If you say, inherited an M cone that is 555 and L cone that is 564, the difference is so small that compaisons are hard and color vision may be affect, but not to the extent of true -nopia color blindness. Some human females but not males can also get 4 cones for similar reasons to the monkeys. Whether this is an actual advantage is another story. A female monkey who gets 3 copies will not have functional color vision if two of these copies are identical.
Also, for genetic reasons that I would probably mess up in explaining, the genes are close to each other for M/L, and thus genetic crossover can muck things up.
Well, you guy’s might’ve been colorblind, but many women will disagree with a tritanopic male’s color choices. “What do you mean you’re wearing THAT!?”
You’d have to show me a couple color swatches, but your assessment of amber sounds alright to me!
This xkcd survey gets linked a lot on here. Scroll down a little bit, where guys have just “green,” girls have “honeydew,” “fern,” and “sea foam.” That part is a joke, but still…
Jeff Lichtman - Also, X0 or Turner syndrome, where one X is missing.
I just realized - a tritanope would have trouble seeing that this website is titled “The Straight Dope”. Poor souls.
This website will give you some idea of the way I see things:
I’m deuteranomaly (green weak) and not completely green blind, so reds are no problem for me and I’m able to see green, I just have trouble distinguishing between certain shades. The top left and middle photos of the Earth aren’t identical to me, but they’re pretty close. Side by side I can see that the green parts (e.g. on Brazil) are a brighter green and not as brown on the left photo, but still pretty close such that I’d be hard pressed to distinguish them if the photos weren’t side by side. I can make out the 3 on both of the Ishihara plates, but the two are virtually indistinguishable. On the photos of the hats, the second hat from the left is very clearly hot pink or red to me in the left photo and greenish brown in the middle photo, but the green hat in the middle looks close to the same shade of green in both photos. I’m told they’re actually very different.
That probably explains why, where I work, all the people who inspect our products have to take a yearly eye exam which includes a color-blindness test. Of course, all the people who do that job are female*, but better to be safe than sorry. I had to take it once (back when I had a boss who thought it would be great if I cross-trained in inspection…ha ha very funny) and I am certifiably not colorblind. Too bad they didn’t have an “eyes bug out after hours of staring at circuits under a microscope” test that I could flunk.
*They’ve hired two or three male inspectors in the time I’ve been with the company, and they’ve never lasted more than two or three weeks. Had nothing to do with colorblindness. I suspect it had more to do with the fact that, like me, they could not stand to stare at a microscope at the same parts over and over, 8 hours a day and 40 hours a week.
Is there an online test that would show exactly what kind of color blindness one might have?
Exactly? No definitely not. You cannot trust a uncalibrated monitor to give accurate colors, nor get a good interpretation. Real CV tests are a battery, including something like Ishihara, anomaloscope, etc.
Otherwise, you could probably tell if you had tritanopia OR protan/deuteranopia. The latter two are very hard to tell apart (see the vischeck link), the difference is mainly in brightness. Your (mine, most people’s) monitor especially can’t do the right luminance or color, and it’s even worse if you have an LCD.
About color-blind people in color-checking professions, there was a movie (can’t remember) about the sexcapades etc. of the actor who played the TV Superman. In it the guy’s best friend was a technician adjusting/demonstrating a color TV for some execs, and it was revealed he was colorblind.
Amusing moment, and I wonder if it is true since the film is ostensibly based on “real life.”
Anomaloscope. Great word, useful for a host of instruments. My wife is a walking anomaloscope.
Thanks for the chart. I always thought that my being colorblind was a foregone conclusion since my mom is a carrier and I am her male child. However, it turns out that it’s only a 50/50 chance. However, both of my uncles are colorblind. I have a younger sister and her son is not colorblind, but it looks like it is possible her daughter is a carrier. Is there a simple test for this?
I’m actually kind of sad that this little unique feature ends with me.
You could reword that as “my being colorblind would be a foregone conclusion if my mom is a carrier and if I inherited the other X chromosome” and it’d be accurate.
You can get to decently high certainty (e.g. 50%) by looking at family members, especially siblings. I am not aware of any way to test for being a carrier. Note Sarabellum1976’s post #38, first line though. If there are any deficiencies, it may be say, less acute than most normal persons, but not significantly worse to the point of abnormality. And therefore not noticeable by tests because the pattern is much closer to a normal person than any abnormality.
The other time a man being colorblind is a foregone conclusion is when his mother is colorblind, since both her X chromosomes would carry the allele for it. Assuming she married a color-normal man, all her daughters would be carriers.
If a color-blind woman married a man with the same form of colorblindness all their kids would have it. If, however, she married married a man with a different form of colorblindness all of her sons would have her color-blindness, all of her daughters would be carriers of it, and half her daughters would also be carriers of their father’s form, meaning they’d have normal color vision but be carriers of two different sorts of color-blindness.
I’m deuteranomalous, meaning my perception of green is “weak” or at least different from the norm. Fully saturated greens look green to me without question, it’s the intermediate shades that are off. So, for example, as you move from the green part of the spectrum towards the yellow there will be colors you perceive as green that I perceive as yellow. Likewise, if you move towards the blue at some point you’ll still be saying “green” and I’ll be saying “blue”. I have a coat that looks brown to me, but to those with color normal vision it’s green. If pressed, you’d likely say it’s a “brownish-green” and I might concede it’s a “greenish-brown”.
This is different than a deuterope, who simply does not perceive green. I believe for them “green” would be perceived as yellow or blue. In speaking with people who don’t perceive red (protanope) reds would be perceived as greys if looking at an object, and red lights are perceived as white lights, though it may be of reduced intensity from other equally bright lights. Of course, that is an outsider’s understanding which may be entirely discredited by an actually -ope type of color blind person.
This is analogous to how I perceive blue.
It’s a little hard to explain. Red and green don’t look “alike” to me as such. But certain shades of red and certain shades of green will be difficult for me to distinguish at first glance.
For example, there’s a common tree or bush around here that periodically produces small bright red fruits. If we’re driving by, my wife will point and say, “oh, look how pretty!” I will just notice a green tree unless I stop and specifically look for the red berries. When I see them, the red berries and green leaves don’t look “alike,” as such.
It can get weird, like I can’t really distinguish very light grays and very light pinks.
It’s worst when using a computer monitor, especially maps that use bright red and green to mark things, like dots. Say you were making a map with a dot showing the location of every professional sports team, if you chose red for football and green for baseball, I would be completely confused.
On political maps, I hate it when instead of a single shade for a single party, the maps are shown with gradients, especially if there are reds, greens, tans, and browns involved. I am unable to see them as patterns of color. It just looks like a random mess to me.
Red-green color blindness must be much more difficult to deal with than just some insensitivity to one color. Have you ever tried different colored lenses to distinquish red and green? I’ve heard on person tell me that was sufficient for him to tell the colors apart, though not to really identify them. This seems to be a matter of debate, the experts say this won’t work. Also, can you identify yellow at all? Would you be able to tell that lemons and apples are definitely different colors? (sorry about all the questions, this subject is beginning to fascinate me).