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Tetrachromats

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Tetrachromats

We know how important for a visual observer the eyesight. Sometimes it is even more important than any aperture or quality instruments.

I was moved recently to research some unusual abilities of human eyesight - to see colours in dim light. What did actually move me to do so? My own ability to see colours on the night skies. I could see different colours of stars, some planetary nebulas and even sometimes in nebula (s) itself. I am not mentioning planets, it is obvious for anyone. I thought that everyone can see the same colours like I could but pretty soon I realised that many people do not see any colours at all or see just some. It is surprised me and made me think twice. I shared my discovery with my daughter, who knows me like the kind of person who does not like to make stories up, and she found some interesting information which actually moved me to research deeper.

To understand how it might happen that one person could see what another could not, let’s start with a quick review of how the average person sees color. Among the many cell types that make up the retina at the back of our eyeball are a type of light-sensing cell called cone cells. Each of these cone-shaped photoreceptor cells contains many copies of a single variety of light-absorbing pigment. For most people, there are 3 types of pigment proteins, or opsins, each of which is expressed in a single class of cone cells.

Each of these opsins has a different set of wavelengths of light that it prefers to absorb. The long-wavelength opsin (L-opsin) absorbs and is most excited by 564 nm wavelengths, which is in the range of red light. The short-wavelength opsin (S-opsin) responds best to blue light around 420 nm, and the medium-wavelength opsin (M-opsin) prefers green light around 534 nm.

When we see color in the world around us, it’s generally a mixture of various wavelengths of light. If you have mostly red wavelengths hitting your eye, then you’ll have a larger proportion of red cone cells (those that contain L-opsin) being excited compared to green or blue cone cells. If you have an equal amount of red and green, then your visual system might interpret the combined excitation of red and green cone cells as yellow. Like the RGB sliders you’d see on a color picker on your computer, your visual system puts together different quantities of your three primary colors to represent the color you’re seeing. It’s actually a little more complicated because you have more red cones and fewer blue cones, but that’s the basic idea.

Despite the fact that people mostly are trichromatic (3 types of pigment proteins, or opsins, each of which is expressed in a single class of cone cells) recent study shows that some rare group of people have tetrachromacy or 4 types of cones like reptiles or birds . Excellent example of tetrachromacy is the famous expressionist Antico who can see million distinctive colours.

http://www.iflscience.com/brain/tetrachromacy-allows-artist-see-100-million-colors

http://www.bbc.com/future/story/20140905-the-women-with-super-human-vision

Tetrachromacy is the condition of possessing four independent channels for conveying color information, or possessing four types of cone cells in the eye. It has been suggested that as women, which I am, have two different X chromosomes in their cells, some of them could be carrying some variant cone cell pigments, thereby possibly being born as full tetrachromats and having four simultaneously functioning kinds of cone cells, each type with a specific pattern of responsiveness to different wavelengths of light in the range of the visible spectrum. Most carriers are women, as suggested by studies.

Point is:

Tetrachromats have a rare ability to see colours that the most people cannot see at all. We well know that the highest percent of human population can see only greyscale in dim light but it is completely different with Tetrachromats. Some of them as Antica, have high sensitivity to colours even in dim light. I do not want to say that I am personally a tetrachromat just because I see some shades of colours in celestial objects (cold blue, deep blue, turquoise, transparent blue, greenish, red, orange, yellow, mat blue and so on) but it makes me think.

This is just my basic research and I am sure that every and each of us has their own unique abilities.

I invite all of you to share your uniqueness, opinions and expand understanding of how we perceive the celestial world around us.

Tatyana

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Ive read somewhere before that women can see colours better then men. Many more female astronomers say they can see colour in faint distant objects then male astronomers. I also read that colour blindness only effects males. Women's eyes apparently have more rods or cones then male eyes, which allow them to see better in low light situations.

I wasnt surprised when i read your real name at the end of your post. Safe to assume you are female because ive never met a guy called Tatyana.

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Interesting. My wife can certainly see colour differences in stars better than me.

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I also read that colour blindness only effects males. 

Colour blindness usually only affects men as the genes for colour vision are on the X chromosome; therefore, defects in it are expressed as men only have one copy. Women have 2 X chromosomes, and so both versions of the gene need to be faulty on both copies for colour blindness to occur. It is possible for a women to suffer colour blindness, but it is very rare.

I wouldn't be surprised if some people have additional types of cone and, therefore, more colours they can perceive. Plenty of animals have more types - the most I know of is the mantis shrimp, with 16 different types.

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Given that colour blindness mainly effects men and one of the top stipulations for airline pilots is that you cant be colour blind, i'm amazed at why more women are not airline pilots. Could be something to do with the mentality in society that being a pilot is a man's job.

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Given that colour blindness mainly effects men and one of the top stipulations for airline pilots is that you cant be colour blind, i'm amazed at why more women are not airline pilots. Could be something to do with the mentality in society that being a pilot is a man's job.

I would love to be a pilot as my dad :). But sadly the mentality in our society affects women even in astronomy :)

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Looking around SLG, there is a healthy number of female astronomers. Even in the real world i bet there are more then we will ever know. On tv, there are 3 i know of in my life:

Heather Couper (i had a crush on her as a kid) and she is the person that got me started in astronomy.

Lucie Green (i do have a thing for her).

Maggie on S@N.

Plenty of female astronauts and women that work behind the scenes at NASA,ESA etc.

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Given that the gene for the red receptor protien is on the X chromosome it is quite possible for a woman to have two varients. If they code for slightly different wavelength peaks then you could get tetrachomy.

This is all a result of our distant ancestors being forced into a nocturnal life during the dominance of the dinosaurs. They needed night vision rather than colour, so lost most cones. It's only in the last few million years that we've managed to regain some degree of colour vision, though pretty poor compared to amphibians, reptiles and birds, none of whose ancestors were forced into a nocturnal life. The humble wood pigeon has vastly better colour vision than we do,

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Fascinating subject!

I know of a number of male astronomers, myself included, who rely on their wives to confirm the colours of stars. Up until now I wasn't entirely certain why women have greater sensitivity to colour than men, but the explanation in the original post clears it up.

I know I have significant colour blindness as I tend to see greens as opposed to blues. I once had a green suit which I wore for about 4yrs, until my wife told me it was petrol blue. Yuk on both counts thinking back!

Mike

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Fascinating subject!

I know of a number of male astronomers, myself included, who rely on their wives to confirm the colours of stars. Up until now I wasn't entirely certain why women have greater sensitivity to colour than men, but the explanation in the original post clears it up.

I know I have significant colour blindness as I tend to see greens as opposed to blues. I once had a green suit which I wore for about 4yrs, until my wife told me it was petrol blue. Yuk on both counts thinking back!

Mike

That probably explains why most women are a bit embarrassed by their chaps solo clothes shopping expeditions. I know mine has been.

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I would love to be a pilot as my dad :). But sadly the mentality in our society affects women even in astronomy :)

Pay visit to IoA at Cambridge, think the men are outnumbered there.

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I do know, though that when I've been tested on the Ishihara cards I've scored 100%, I can also easily see both the 404 and 766 / 769 nm lines of potassium, at one time I could also see the H&K line of ionised calcium.

*shrugs*

Pretty normal I expect.

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I'm sure I recall reading that BBC article when it was first published.  Very interesting.  I've found from time to time that there are colours my wife and I completely disagree over.  For instance I have a top that I am absolutely sure is blue.  And quite obviously blue.  Yet my wife claims it is really a shade of green.  I cannot see any possible way its colour could be interpreted as green no matter how far I try to stretch the definition.

Of course men do know only too well that women see colours differently.  Who hasn't been told "You can't wear those trousers with that shirt.  They clash horribly!" whilst thinking "Can't see anything wrong with it myself..." :D

James

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I think I may interpret individual colours as a slightly longer wavelength than some others. I see blue/green where others say blue. Likewise what some call yellow is a tangerine to me. I wonder if this is down to conditioning as to what a colour is called rather than what it is. Certainly there is no way to know what anyone else is seeing whatever it is called. I used to wonder if different people actually saw completely different ranges of colours. There's no way of knowing. We both call it red for instance but what you call red might be an unimaginable hue to me.

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Very subjective, especially if you ask a queue of observers at an outreach event what colours they can see.

I read somewhere that colour blind eyes can be more acute and have a better chance of seeing faint targets. Certainly I spot tiny binaries that leave even some seasoned observers searching, hurrah !

Nick.

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I would love to be a pilot as my dad :). But sadly the mentality in our society affects women even in astronomy :)

My daughter flew to Barbados some years ago and after the plane had executed a flawless landing the first officer came on the intercom to tell them that the co pilot had taken the controls for her very first solo landing with passengers.

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Very subjective, especially if you ask a queue of observers at an outreach event what colours they can see.

I read somewhere that colour blind eyes can be more acute and have a better chance of seeing faint targets. Certainly I spot tiny binaries that leave even some seasoned observers searching, hurrah !

Nick.

I agree that how we perceive colours could be really subjective.

The point of this research is that it is possible for some rare individuals, because of their condition (tetrachromacy, for example), to see colours in DSO where others CANNOT see it at all.

Just to mention that tetrachromacy can affect both genders according to study, not only females, but mostly females :)

Regards

Tatyana :)

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