Do color blind people see a different color sky?

[Coreece 190]

I'm just curious...

Also, is color actually real or is it just our brain that makes it seem real...if we were wired differently and processed color differently, would our scientific knowledge of primary colors be different eventhough the only thing that changed is our way we precieve light and not the actual light itself or the object from which the light is reflected?

And...could color blindness actually be a beneficial genetic predatory adaptation since some studies show that those who "suffer" from color blindness can diferentiate camaflouge more accurately?

Your secrets are the true reflection of who you really are...

[DJL 232]

I really have to suggest a source other than dropzone.com Speaker's Corner but since I have the time. Something may be real regardless of our ability to detect it. We know that the visible light spectrum is real because our eyes are capable of detecting it. We didn't know that there was a lot more to the spectrum until we figured out how to detect it. For the rest of it, google.

"I encourage all awesome dangerous behavior." - Jeffro Fincher

[peregrinerose 0]

Color 'blindness' isn't really color blindness at all.... it's just a different way of identifying hues. Most color 'blindness' is the inability to differentiate some shades of red/green or yellow/blue, not a world of black and white. 1/8 guys has color vision issues, and 1/20 women. Even in the 7/8 guys with 'normal' color vision, they do not perceive as many shades or hues as 'normally' color visioned women.

Total color vision loss, achromatopsia, is only possible through total loss of the cones of the eye. It also causes 20/400ish visual acuity (best corrected). Read "Island of the Colorblind" by Oliver Saacks for more information.

'Color' is a perception. The wavelength of light reflected by an object, however is something that can be objectively measured, not just subjectively determined.

Do or do not, there is no try -Yoda

[Andy9o8 0]

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Even in the 7/8 guys with 'normal' color vision, they do not perceive as many shades or hues as 'normally' color visioned women.

Anyone who has ever worked in retail can tell you that.

Example:
Women: Amber, Coral, Persimmon, Pumpkin, and Salmon.
Men: Orange, orange, orange, orange and pink.

[billvon 2,435]

>Do color blind people see a different color sky?

Literally yes. And they call that color 'blue' just like you do.

Many people perceive colors differently. Some women, for example, have genetic encodings for two different blue receptor dyes (one on each arm of the X chromosome) whereas men have only one. And while that means that some people can differentiate more colors than others, since we are all taught the sky is blue, we all call it by the same name.

>could color blindness actually be a beneficial genetic predatory adaptation . . .

Unlikely. It is more likely that it is simply not a very deadly mutation, and thus is not removed from our genome by the normal process of evolution. Sort of like light skin, which predisposes you to skin cancer, but not to the extent that it is removed from the gene pool.

[kelpdiver 2]

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I'm just curious...

Also, is color actually real or is it just our brain that makes it seem real...if we were wired differently and processed color differently, would our scientific knowledge of primary colors be different eventhough the only thing that changed is our way we precieve light and not the actual light itself or the object from which the light is reflected?

Color is certainly real, but also quite subjective to the environment, both where the object is, and of the viewer. Since most color blindness is red/green, most people's "blue" is pretty similar.

Underwater, colors change due to depth and ambient light levels unless you carry your own light, which means that any notion of color in UW photography is very open to interpretation.

[Capt.Slog 0]

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1/8 guys has color vision issues, and 1/20 women. Even in the 7/8 guys with 'normal' color vision, they do not perceive as many shades or hues as 'normally' color visioned women.

.

Right, men cannot see colors like "lavender", "fuschia", "carmine" and "celadon".

[Coreece 190]

Thanks for the info...as always it's much appreciated.

I know my ignorance on the matter might have been a lil painful...

My grammar was horendous....and I've never noticed the spell check button...wtf?

Your secrets are the true reflection of who you really are...

[downwardspiral 0]

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1/8 guys has color vision issues, and 1/20 women. Even in the 7/8 guys with 'normal' color vision, they do not perceive as many shades or hues as 'normally' color visioned women.

.

Right, men cannot see colors like "lavender", "fuschia", "carmine" and "celadon".

The fact that you even know those colors exist is grounds for removal of your guy card.

www.FourWheelerHB.com

[peregrinerose 0]

Actually, it is possible that color vision issues could be beneficial. As colors are not seen the same, a figure/ground task (say spotting food, or a predator, hidden in the shadows or a bush) could be easier for someone with color vision problems, given the right coloring differences. On a Ishihara color vision test, there are plates that look like nothing to someone with 'normal' vision, but someone with red greed deficiency can easily see a number.

Do or do not, there is no try -Yoda

[chuckakers 370]

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is color actually real or is it just our brain that makes it seem real...if we were wired differently and processed color differently, would our scientific knowledge of primary colors be different even though the only thing that changed is our way we precieve light and not the actual light itself or the object from which the light is reflected?

Acid?

Chuck Akers
D-10855
Houston, TX

[billvon 2,435]

> As colors are not seen the same, a figure/ground task (say spotting
>food, or a predator, hidden in the shadows or a bush) could be easier for
>someone with color vision problems, given the right coloring differences.

In the case of someone with different color receptors (i.e. ones tuned to different light frequencies than the rest of us) I would agree.

In the case of true color blindness, I would tend to disagree. Red-green color blindness (protanopia) _removes_ a receptor that a person would otherwise have available to better understand a colored scene. That's not to say they would not see things; indeed, they may compensate in other ways, much as a blind person has a much more developed sense of hearing, and can recover more spatial cues from their hearing than sighted people can.

>On a Ishihara color vision test, there are plates that look like nothing
>to someone with 'normal' vision, but someone with red greed deficiency
>can easily see a number.

Right, and that's why some types of color blindness can help people see through camouflage - because camouflage designers attempt to use absorptive pigments to approximate the colors of things nearby.

A simple example is a computer monitor. They use three colors (red, green, blue) to represent all colors. We perceive red and green together as yellow, even though red and green are nowhere close to each other in terms of color frequency. Someone with different color vision (i.e. someone whose color receptors clustered in the blue, instead of the red, end of things) would see a yellow object on a computer screen as a bizarre red/green combination, instead of the yellow that we (of more limited vision) see. Thus, a yellow "camouflage" pattern on a monitor would blend quite well with a yellow background to us, but to a person with the altered receptors, would stand out like a sore thumb.

[peregrinerose 0]

I'm not sure why you disagreed with me in one paragraph, but then agreed at the end with regard to seeing through camo... that's the very trait that can be advantageous in some animal populations.

But 'true' color blindness is NOT the removal of one photoreceptor type... it's the total lack of cones at all... achromatopsia, which has far more pressing complications than color descrimination.

Color vision deficiency has many types... even in red-green deficiencies there are multiple types, protanopia is only one of them, deutanopia another. And even among those there are varying degrees and types. Then there's tritanopia or yellow-blue issues. And those are just the congenital forms. Acquired color vision deficiencies can stem from anything from macular disease, cone dytrophies, to optic nerve disorders.

Do or do not, there is no try -Yoda

[billvon 2,435]

>I'm not sure why you disagreed with me in one paragraph, but then
>agreed at the end with regard to seeing through camo...

Because seeing through artificial camouflage is a great talent to have when you're at war, but not so important when you're living in a natural environment without such pigments.

The only time it would be truly advantageous is if those pigments were present in the natural world as well, and thus a color blind person could recognize many natural patterns (dangerous or otherwise) that people with normal color vision cannot. I tend to think this is not the case because:

1) If a specific recessive genetic characteristic that seems to be detrimental is seen in more than about 5% of a population, odds are it has a hidden benefit (sickle cell anemia would be an example here.) However, if it's much lower than that, odds are that it is merely a defect. And the most common form of color blindness only affects about 1% of people.

2) Because of how our genome is set up, most hereditary color blindness affects males only. Sex-linked traits like this are even harder to 'evolve out' of a population, and thus are more likely to stick around even with no benefit.

3) Whenever a recessive trait has a strong benefit it is very rapidly selected for because of how Mendelian inheritance works. In other words, if it was truly an advantage to have fewer color receptors, we'd probably all have fewer color receptors, because our ancestors with more color receptors would have died out long ago.

That being said, you could argue that there might be a societal benefit to colorblindness; perhaps you could imagine a hunting party made up of a number of normally sighted people and one color blind person who could recognize the 5% of dangerous/desireable patterns that the normally sighted people could not, and thus a heterogenous hunting party is more successful than one made up exclusively of either type.

But that's a harder argument to make, I think. Once we started hunting cooperatively we also started protecting our weaker members (including the ones who couldn't see as well.)

>But 'true' color blindness is NOT the removal of one photoreceptor
>type... it's the total lack of cones at all...

Right, but I think when most people talk about color blindness they are talking about the more common types of partial loss of color differentiation.

[headoverheels 291]

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1/8 guys has color vision issues, and 1/20 women. Even in the 7/8 guys with 'normal' color vision, they do not perceive as many shades or hues as 'normally' color visioned women.

.

Right, men cannot see colors like "lavender", "fuschia", "carmine" and "celadon".

But we can really split the shades of gray.

[aykay 0]

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Actually, it is possible that color vision issues could be beneficial. As colors are not seen the same, a figure/ground task (say spotting food, or a predator, hidden in the shadows or a bush) could be easier for someone with color vision problems, given the right coloring differences. On a Ishihara color vision test, there are plates that look like nothing to someone with 'normal' vision, but someone with red greed deficiency can easily see a number.

Like this???

[peregrinerose 0]

1. 1 in 8 men (12%) and anywhere from 1-5% of women (depending on which source you use) has color vision deficiency. Your numbers are very far off.

2. True that SOME forms of color vision issues are sex linked, but not all. There are something like 16 different genetic quirks that cause congenital color vision alteration, not even counting acquired vision loss.

3. Some populations DO have 100% color vision loss... check out the book I referenced above. They seem to do pretty well that way.

4. There's a difference between 'benefit' and 'strong benefit'... no one said that color vision deficiency was a strong benefit, only that in certain scenarios it could pose a slight advantage. A wavelength of light is still a wavelength, whether on camo or shrubbery.

5. Just because 'most people' use a certain terminology does not make it accurate.... if you want to come accross as knowledgeable in a field, you need to use accurate terms, not lay terms, especially when debating with someone with multiple advanced degrees in the field.

Do or do not, there is no try -Yoda

[billvon 2,435]

>1 in 8 men (12%) and anywhere from 1-5% of women (depending on which
>source you use) has color vision deficiency. Your numbers are very far off.

Right. But the incidence of most types of color blindness is not much over 1% - and you were talking about the odds that color blindness was a beneficial heritable trait, which means that it has to be a single beneficial heritable trait. People who lose color vision due to trauma, for example, can't really be counted as part of a heritable genetic trait.

The one 'higher rate' color blindness is standard red-green blindness, and that can affect 3-5% of the population.

>Some populations DO have 100% color vision loss... check out the book
>I referenced above. They seem to do pretty well that way.

Sure. A lot of organisms don't have trichroic color vision and do OK. Heck, seals and sea lions are pretty much monochromatic, and have no problem hunting. Most mammals are dichromatic (red-green) color blind, and most of them do just fine.

>4. There's a difference between 'benefit' and 'strong benefit'... no one said that
>color vision deficiency was a strong benefit, only that in certain scenarios it
>could pose a slight advantage.

Right. And if it _consistently_ proved to be a slight advantage overall, we'd evolve to have it.

However, the opposite has happened. Our ancestors were dichromats, and indeed most of the animal world still is. That means that the camouflage schemes out there are designed to work best on organisms with red-green color blindness. When we got that third cone, we immediately had a competitive advantage over all the other animals out there who could not tell red from green, or (more importantly) poisonous flowers and fruits from good ones.

Thus it was a trait we maintained. With evolution being somewhat capricious, that trait ended up on the X - Y chromosome, and thus is not 'backed up' in men - which is why men have a higher incidence of colorblindness.

If my assertion were valid, it would stand to reason that animals who rely even more on sight than we do would have ever more sophisticated visual systems, allowing them to see even more colors than we do. And indeed that is the case. Many birds have four types of cones, and can thus see a lot more colors than we can. Pigeons may have _five_ types of cones, giving them outstanding color vision.

If there were a slight benefit to having fewer cones, it's likely that the easier-to-replicate two-cone system would rapidly win out over a three, four or even five cone system.

>A wavelength of light is still a wavelength, whether on camo or shrubbery.

Agreed. And in _general_ being able to tell many wavelengths apart will help you more accurately determine what it is you're looking at. There are exceptions, as in the manmade camo that doesn't accurately match the background when you take away the red-green differentiator.

>Just because 'most people' use a certain terminology does not make it
>accurate.... if you want to come accross as knowledgeable in a field, you need
>to use accurate terms, not lay terms, especially when debating with someone
>with multiple advanced degrees in the field.

Ah, I see the issue here. I don't care if anyone thinks I am knowledgeable or not. It's just a subject that interests me.

[peregrinerose 0]

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The one 'higher rate' color blindness is standard red-green blindness, and that can affect 3-5% of the population.

So it's possible that since the rate for rg color deficiency is higher than the 1% you stated in your other post was the cut off between fluke and possible advantage, there may be some minor asset to it? Considering that humans have been around a fairly short amount of time, the amount of evolution regarding the eye has had relatively little time to take place. Given our rather artificial environments, evolution is probably taking a different route than it did back in hunter/gatherer day as well. A more appropriate comparison would be incidence of color vision now compared to 1500+ years ago, data that's just not available at this time.

With regard to your bird analogy, it doesn't really fly (yeah, bad pun)

Bird vision is completely different than what either of us can truly comprehend. First, their needs are completely different than ours... flower and seed identification from large distances, mate selection regarding plume colors. Second, they have 3 types of photoreceptors (rod, cone, double cone), not just 2 (rod/cone) like ours. Third, they also can see in the UV light spectrum, so their rainbow and color vision is very different than ours. Not necessarily better or worse, just geared toward a totally different type of vision (seeds, for example, have a different UV signature than the surrounding flora, so the UV perception is important. Mate selection is also often UV impacted). Bird retinas do not have the network of blood vessels that we do, over top of the retina and blocking many photoreceptors. Their cones are more densely packed than ours. Nocturnal birds have more rods which allow for better night and motion vision, but poor detail vision. They also have a tapetum lucidum that improves the ability to see in the dark. A few nocturnal mammals have it as well. Even more importantly than retinal changes, birds have a completely different visual cortex than we do, they can percieve details without scanning and capture the 'whole picture differently than we can, while we are more able to focus on a particular detail than they are. Bird eyes give them a greater field of view than we have, however completely eliminates stereoscopic vision (with the exception of owls).

Turtles, fish, and bees also have 4 types of cones too... again, they have different visual needs than we do, so it makes sense. Octopi have what we would think of as inverted retina from ours, but from a visual efficiency stance, in some ways developmentally, it makes more sense to have it structured in that way.

Vision and visual perception and evolution thereof is far more complex than the rather simplistic facets that you're bringing up. As a result of this, you can't truly compare bird with human eyes, since structurally on a host of levels, not just cone numbers, they are very different entities with different functions.

It's better to go with primate eyes alone, and the research shows that although trichromacy is better for fruit forraging and identification, dichromacy is much better for color-camoflauged stimuli (detecting predators, for example), which is likely why the incidence is so much higher in the human population than would be determined by mere 'fluke'.

Do or do not, there is no try -Yoda

[MartinOlsson 0]

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Unlikely. It is more likely that it is simply not a very deadly mutation, and thus is not removed from our genome by the normal process of evolution. Sort of like light skin, which predisposes you to skin cancer, but not to the extent that it is removed from the gene pool.

I don't understand this. Do you believe that light colored skin is a benign, but not advantageous, mutation and not an evolutionary adaptation?

/Martin

[Andy9o8 0]

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Unlikely. It is more likely that it is simply not a very deadly mutation, and thus is not removed from our genome by the normal process of evolution. Sort of like light skin, which predisposes you to skin cancer, but not to the extent that it is removed from the gene pool.

I don't understand this. Do you believe that light colored skin is a benign, but not advantageous, mutation and not an evolutionary adaptation?

Leave it to the Scandinavian to ask this.

Anyhow, I was always under the impression that lighter skin was an adaptation to allow people in higher latitudes to produce adequate Vitamin D despite the lesser UV intensity.

[billvon 2,435]

>Do you believe that light colored skin is a benign, but not advantageous,
>mutation and not an evolutionary adaptation?

Well:

1) Adaptations are basically mutations that are passed on

2) Any such adaptation often has multiple effects.

In this case, you have the choice between dark skin (=better protection from UV) and light skin (=lesser protection from UV.) One side effect is folate production. Folate is broken down by UV, so too much UV on a fair skinned person would be dangerous and lead to problems with reproduction. Another side effect is vitamin D production. It's easier for fair skinned people to produce vitamin D when exposed to sunlight.

So whether it is advantageous or not depends on your environment. If you lived in a hot area where no one used much clothing because you didn't need it (and in fact it hampered cooling through sweating) then darker skin is definitely beneficial. If you live in an area where you eat a diet (like lots of fish) that contains a lot of vitamin D, _and_ the danger from UV is not as strong, then it doesn't really matter one way or another, and skin color 'wanders' (i.e. is not selected for or against, so is whatever random mutation drives it to be.) If you live in an area where you don't get enough vitamin D in your diet, _and_ there's not much sun, _and_ you can protect yourself when there is (i.e. clothing) then lighter skin is advantageous - because you produce more vitamin D without losing too much folate.

So to get back to the original question, in an area where vitamin D is plentiful, and there's not much of a folate-depletion risk from solar UV, then light skin isn't all that beneficial or harmful. It increases your risk of skin cancer, but since that usually becomes fatal _after_ childbearing years it doesn't play into evolution very much.

[MartinOlsson 0]

Well, I'm fully and thoroughly aware of what a mutation is. Maybe I was just marking words, but what I was aiming at is that light colored skin is a result of evolutionary force. Not a fluke that is allowed just because of lack of disadvantage.

[billvon 2,435]

>Not a fluke that is allowed just because of lack of disadvantage.

I'd argue that in some places, where it confers no advantage and no immediate disadvantage, it is precisely that. (Doesn't mean there's anything wrong with being white, of course.)

[MartinOlsson 0]

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I'd argue that in some places, where it confers no advantage and no immediate disadvantage, it is precisely that. (Doesn't mean there's anything wrong with being white, of course.)

But that is a modern (or at least post migration period) phenomenon. Since skin color probably has evolved during many generations i would say there is mostly evolutionary drive.

I'm deeply offended by your questioning of the evolutionary value of my light skin ;)

/Martin