Color perception of your con-species

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eldin raigmore
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Color perception of your con-species

Post by eldin raigmore »

This was supposed to be a questionnaire. If I don't do it right please help.

What wavelengths of electromagnetic radiation can your con-species perceive and focus into an image?

Which ones can they tell apart?

If their atmosphere is like Earth's, they can't see anything shorter than 200 millimicrons (frequency 1.5 petahertz (1.5 * 10^15 Hz), because the atmosphere is opaque to wavelengths shorter than that.

But I haven't been able to find any mention of any real-life terrestrial natspecies that can see wavelengths shorter than 300 millimicrons (1 petahertz).

Assuming their biology is like ours -- water-based -- they probably can't "see" (that is, focus and form images with, as opposed to merely "detect") radiation with a wavelength longer than about 1450 millimicrons (1.45 microns, frequence about 2 terahertz or 2 * 10^12 Hz), because water is opaque to infrared longer than that.

But AFAICT all earth-based color-vision uses a subset of just four optically-sensitive pigments, a UV one, a "short" one, a "medium" one, and a "long" one. Different species have managed to shift the peaks of the response curves for some of these to slightly shorter or slightly longer wavelengths, but, still, the "long" sensor doesn't sense IR light much longer than something between 740 and 780 millimicrons.

If they're warm-blooded, they're probably "blind" to IR light longer than 740 to 780 millimicrons anyway, because their eyes glow in that frequency. But maybe their eyes hang out of their bodies and are cooler than the rest of their bodies, like testicles.

The militaries' active IR night-vision systems detect light between 750 and 1000 millimicrons (300 to 400 Terahertz).

Pit-vipers' pits respond to IR light up to about 2000 millimicrons long (150 Terahertz).

I don't quite understand what I've read about an "IR transmissivity window" for Earth's atmosphere; it's either up to 5000 millimicrons (5 microns) or up to 50000 millimicrons (50 microns). Either way, the frequency is still in the Terahertz range, and water scatters most of it so that it can't be focused into an image by a biological lens. Pit vipers detect its direction quite well, using a "pinhole" focussing system; but it's hardly image-forming.

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So:
What's the shortest wavelength, highest frequency EM radiation your conspecies can detect and focus and use to perceive images? If it's shorter than 200 millimicrons, why?

What's the longest wavelength, highest frequency EM radiation your conspecies can detect and focus and use to perceive images? If it's longer than 1450 millimicrons, why?

What's the just-noticeable difference in their "color perception" of EM radiation? Is it different at different parts of the spectrum? Is less than 10 millimicrons (say they can tell the difference between 500 millimicrons and 505 millimicrons)? Between 10 and 20? between 20 and 50? between 50 and 100?

How many different light-perceiving pigments do your conspecies' eyes have?

Do they use oil-drops in their cone-cells, like some birds and some reptiles, to make the cone-cells better able to tell the difference between shorter and longer wavelengths?

How many different kinds of cone-cells do they have? (Mantis shrimp are said to have 12 or 13 types of cone cells. They can have any of 4 types of light-sensitive pigment; and they can have either no oil-drop or any of 5 kinds of oil-drop.)

-------------------------------------------------------------------------------------------------------

Mantis shrimp can perceive four kinds of linearly polarized light and two kinds of circularly polarized light.
I have no idea what that sentence means. But it means that mantis shrimp can tell exactly everything there is to tell about how light is polarized.

How good are your conspecies at detecting polarization and discriminating between different kinds of polarization of light?
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Re: Color perception of your con-species

Post by clockworkbanana »

I'd like to answer these, even partially, but I don't know for my species. Their atmosphere has a slightly higher level of CO2, is slightly thicker because their planet is more massive, and their star is smaller than Sol, so it gives off more red light and less blue (and UV?). So, I'm still unsure what colors or how they would see.
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Re: Color perception of your con-species

Post by Micamo »

Daron is hotter than the sun, so it produces slightly stronger UV. Agyon can see in the near-UV range (400-250), and have a fourth cone for doing so. Though they look white to humans (and their natural prey), their bodies are covered in a rainbow of colors only visible to them, making identifying each other easy across distances, even during a snowstorm.
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Re: Color perception of your con-species

Post by zelos »

One of my species see quite wide range going from high UV to IE mostly because there is little light where they live (not completely absent) and hence have evolved it
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Re: Color perception of your con-species

Post by Rik »

I know I've considered this question for my conbiology in the past, but those scraps of paper must have disappeared long before I bought my first computer.

I think your question (What wavelengths of electromagnetic radiation can your con-species perceive and focus into an image?) may be a little too homocentric for me to offer an answer beyond "none that I know of". We know from our own subjective experience that sight and heat are separate 'senses', though they're in fact the same thing at different frequencies. Sight is probably perceived as an 'image' by us because the organs that collect those frequencies are highly localised to one part of the body, and processed in specific parts of the brain, whereas the perceptors for heat frequencies are distributed across the entire skin, thus we perceive it as a 'feeling'. So creatures that have a much wider distribution of light receptors across their body might model changes in the visual spectrum as a feeling rather than as images.

You mention pit vipers. I wonder if the positioning of their pit organ (between the eyes and nostrils) acts as a 'third eye', adding to the visual images their eyes create - effectively an additional 'colour'? Maybe some brave scientist has already done the work to see if the brain circuits for the eyes and the pit organ interact/overlap, in which case the answer would probably be: yes.

The parietal eyes of a few vertebrate species can detect light radiation, but don't make use of rods and cones. I've no idea how data from these organs are interpreted alongside the more image-like information from the regular eyes. Given their connection to a specific part of the brain separate from the visual regions I suspect it might be as a separate sense rather than being integrated into the image. (I do know that the main effect of my pineal gland on me is to tell me when I'm tired - a feeling rather than an image.)

Electric eels detect EM at around 25Hz through perceptors distributed through their skin - so probably another feeling: two different types of heat? If you add in the pressure sensors in the lateral line that would make 3 different sources of information (4 including sound waves), like cones - I wonder if electric eels can 'visualise' their surroundings like we (or cows with their all-round sight) see it?

Conbiologically, I quite like the idea of having an animal perceive/use radio waves - it shouldn't be too difficult to explain/develop as radio waves work by inducing an electric current in a metal wire. Heck, if the real world can come up with electric eels, then why not this? If the radio wave receptors were limited to, say, the microwave range (1-2mm) in antenna close to the visible-spectrum eyes, maybe the data they pick up could be used to add to a visual image?
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Re: Color perception of your con-species

Post by clockworkbanana »

I think I saw recently that some group of scientists had found that the heat receptors in pit vipers are wired to the area for vision in their brain.

Here. It's a couple paragraphs down. It doesn't say that these two senses are overlapped, but at the least they are closely associated.
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Re: Color perception of your con-species

Post by eldin raigmore »

All good answers so far.
http://www.physorg.com/news76249412.htmlThanks, clockworkbanana.
@Micamo, that looks pretty well thought-out along the lines of what I was hoping I was asking.
Rik wrote:I think your question (What wavelengths of electromagnetic radiation can your con-species perceive and focus into an image?) may be a little too homocentric for me to offer an answer beyond "none that I know of".
Maybe so; or at least it might be too sight-centric.
I think animals with compound eyes, such as insects, do in fact have imaging ability. In case they don't, well, I didn't intend to leave them out, but it might be better to modify "my questionnaire" to include that as an additional question, than to modify the existing question to include them.
I did intend to leave out the kind of EM radiation that can be seen only once per eye because it would ruin the eye. I also intended to leave out, at least in that one question, pit vipers' pits, because they don't form images via living lenses. It's nevertheless a very interesting kind of sense, and I'd like to include a question that would cover it. They have to have "software" that processes what they get into an image-like something, or into data they can use as if it were an image.
Humans can, of course, detect ultraviolet light on our skins; at least, white people can, by being stupid on the beach in the summer and not wearing any sunscreen. That's not what I meant either. I meant something that one can sense rather quickishly and react to rather soonishly. By the time someone realizes they're sunburnt it's too late to do much about it.
Electric eels' electro sense isn't an "EM radiation" sense, is it? It's a sense for an electric field, right? Similarly the sense of the Earth's magnetic field that some birds and fishes are supposed to have, isn't an "EM radiation" sense. "EM radiation" means light-like radiation, from gamma rays through X-rays through ultraviolet through visible light through infrared through radio waves.
But many species use sound for "imaging", or at least, effectively for imaging, maybe as pit vipers use the input to their pit-organs. That's also be interesting; as would anything similar an electric-eel-like sense could be used for.
I once read an SF story about species living on a body with nearly no atmosphere and with an ambient temperature close to the boiling point of many of their nutrients. They had a "sight -- smell" like sense; they had chemoreceptors (like smell- and taste- -organs) as the "retina" of an organ like a pit-viper's pit (or like an eye, for that matter), shaped rather like a pinhole camera. The molecules they "smelled" tended to travel in straight (or, practically, straight-ish) lines, so this arrangement worked for them.

-----------------------------------------------

I guess the questions I asked in the first post were only some of the questions I'd actually like discussed. But I still think they're the main ones.

What EM radiation wavelengths/frequencies can your species sense? That may have all kinds of answers.

What EM radiation wavelengths/frequencies can your species see by?
I still think shorter than 200 nanometers is unlikely, at least if their atmosphere is like Earth's.
I still think longer than 740 or 780 nanometers is unlikely if they're warm-blooded. Vertebrate's ears can't hear sounds that would be drowned out by the sounds our blood makes in our ears. Warm-blooded animals can't see by wavelengths actully emitted by their own eyeballs.
And I still think longer than 1400 or 1450 nanometers is unlikely if their lenses contain water.

An over-all sense of light, say, "feeling" specific wavelengths of "light" all over the skin, would not be good enough to form an image. It's not just that an image is sensed in a particular small part of the body; it's that if one can form an image, one can tell which direction which parts of the scene are coming from, to a very fine distinction of directions.
With a "whole-skin retina", though, the discrimination of which direction which parts of the received radiation were coming from, would be no finer than maybe 180 or 120 or 90 degrees or something like that.
That'd be great for letting you know that there's something you need to turn around and look at! It even gives you a strong hint which direction to look.
But it's not really helpful for figuring out what it is, what it's shaped like, and exactly where it is.

-----------------------------------------------

The other thing I was asking about was, how well can they tell these wavelengths/frequencies apart?
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Re: Color perception of your con-species

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I'm not sure yet whether I want to have the oil droplets, I'm having trouble finding information on exactly what they do for color perception.
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Re: Color perception of your con-species

Post by eldin raigmore »

Micamo wrote:I'm not sure yet whether I want to have the oil droplets, I'm having trouble finding information on exactly what they do for color perception.
They help the perceiver distinguish between different mixes of wavelengths.

For instance, suppose you have two photo-reactive photo-sensitive visual pigments, VP500 and VP600.

Suppose VP500 reacts at:
100% to wavelength 500 nm,
Spoiler:
95% to wavelengths 510 nm or 490 nm,
90% to wavelengths 520 nm or 480 nm,
85% to wavelengths 530 nm or 470 nm,
80% to wavelengths 540 nm or 460 nm,
75% to wavelengths 550 nm or 450 nm,
Spoiler:
60% to wavelengths 560 nm or 440 nm,
45% to wavelengths 570 nm or 430 nm,
30% to wavelengths 580 nm or 420 nm,
15% to wavelengths 590 nm or 410 nm,
0% to wavelengths 600 nm or longer or 400 nm or shorter.

Similarly, suppose VP600 reacts at:
100% to wavelength 600 nm,
Spoiler:
90% to wavelengths 620 nm or 580 nm,
80% to wavelengths 640 nm or 560 nm,
75% to wavelengths 650 nm or 550 nm,
Spoiler:
60% to wavelengths 660 nm or 540 nm,
30% to wavelengths 680 nm or 520 nm,
0% to wavelengths 700 nm or longer or 500 nm or shorter.

If the only chromoceptors stimulated by wavelengths between 500nm and 600nm are VP500 and VP600, then the light at any single wavelength between 500nm and 600nm can be mimicked by a mixture of light at 500nm with light at 600nm.

For instance,
100 photons at 550 nm could be mimicked by 75 photons at 500nm with 75 photons at 600nm;
because light at 550nm makes both the VP500 cones and the VP600 cones respond at 75%.

For more instances,
Spoiler:
100 photons at 520 nm could be mimicked by 90 photons at 500nm with 30 photons at 600nm;
100 photons at 540 nm could be mimicked by 80 photons at 500nm with 60 photons at 600nm;
100 photons at 560 nm could be mimicked by 60 photons at 500nm with 80 photons at 600nm;
100 photons at 580 nm could be mimicked by 30 photons at 500nm with 90 photons at 600nm.
But now, suppose you also had differentially-opaque/differentially-transparent droplets of oils, OD500 and OD600.

Suppose OD500 lets through;
0% of the light at a wavelength of 500nm,
Spoiler:
5% of the light at wavelengths of 510nm and 490 nm,
10% of the light at wavelengths of 520nm and 480 nm,
15% of the light at wavelengths of 530nm and 470 nm,
20% of the light at wavelengths of 540nm and 460 nm,
25% of the light at wavelengths of 550nm and 450 nm,
Spoiler:
40% of the light at wavelengths of 560nm and 440 nm,
55% of the light at wavelengths of 570nm and 430 nm,
70% of the light at wavelengths of 580nm and 420 nm,
85% of the light at wavelengths of 590nm and 410 nm,
100% of the light at wavelengths of 600nm or longer and 400 nm or shorter.

Similarly, suppose OD600 lets through;
0% of the light at a wavelength of 600nm,
Spoiler:
10% of the light at wavelengths of 620nm and 580 nm,
20% of the light at wavelengths of 640nm and 560 nm,
25% of the light at wavelengths of 650nm and 550 nm,
Spoiler:
40% of the light at wavelengths of 660nm and 540 nm,
70% of the light at wavelengths of 680nm and 520 nm,
100% of the light at wavelengths of 700nm or longer and 500 nm or shorter.

Now suppose you have four types of cones that respond to wavelengths of 500nm to 600nm, instead of only two:
VP500 cones without oil-droplets,
VP500 cones with OD600 oil-droplets,
VP600 cones without oil-droplets,
and VP600 cones with OD500 oil-droplets.

Now, light at 550nm makes the VP500-without-oil cones and the VP600-without-oil cones both respond at 75%; but the VP500-with-OD600 cones and the VP600-with-OD500 cones both respond at 18.75% (about 19%).
Light at a wavelength of 500nm always equally stimulates the VP500-without-oil cones and the VP500-with-OD600 cones equally, and always fails to stimulate both the VP600-without-oil cones and the VP600-with-OD500 cones.
Likewise, light at a wavelength of 600nm always equally stimulates the VP600-without-oil cones and the VP600-with-OD500 cones equally, and always fails to stimulate both the VP500-without-oil cones and the VP500-with-OD600 cones.
So any mix of wavelength-500nm light with wavelength-600nm light will get the same reaction from the VP500 cones whether or not they have an oil-droplet, and will get the same reaction from the VP600 cones whether or not they have an oil-droplet.
No single-wavelength light in the range of 500nm to 600nm can be mimicked by any mixture of two other wavelengths in that range.

Apparently many birds who have cones with oil-droplets need to be able to differentiate "colors" in the oranges-and-yellows better than cones without oil-droplets would enable them to do. In particular they sometimes need to be able to tell the difference between, on the one hand, a mix of two wavelengths, and, on the other hand, a single wavelength, when without the oil-droplets they couldn't do that.

_______________________________________________________________________________

Suppose you had visual pigments VP200, VP300, VP400, VP500, VP600, and VP700.
Suppose:
Spoiler:
VP200 responds at 100% to 200nm, at 75% to 250nm, and at 0% to 300nm;
VP300 responds at 100% to 300nm, at 75% to 350nm or 250nm, and at 0% to 400nm or 200nm;
VP400 responds at 100% to 400nm, at 75% to 450nm or 350nm, and at 0% to 500nm or 300nm;
VP500 responds at 100% to 500nm, at 75% to 550nm or 450nm, and at 0% to 600nm or 400nm;
VP600 responds at 100% to 600nm, at 75% to 650nm or 550nm, and at 0% to 700nm or 500nm;
VP700 responds at 100% to 700nm, at 75% to 750nm or 650nm, and at 0% to 800nm or 600nm.
If there are no oil-droplets, the VP400 cones by themselves can't tell the difference between wavelength 350nm light and wavelength 450nm light; VP400 cones respond at 75% to both of those wavelengths. But 450nm light stimulates the VP500 cones too, whereas 350nm light does not.

If, between the peak-response wavelengths of any two visual pigments, one finds a range of wavelengths to which only those two pigments respond, then any single wavelength in the interior of that range can be imitated by a mix of two other wavelengths in that range, and any mix of any two wavelengths in that range can be mimicked by some single wavelength in that range.

But if we had oil-droplets OD200, OD300, OD400, OD500, OD600, and OD700, such that:
Spoiler:
OD200 blocks all wavelength-200nm light, lets through 25% of 250nm light, and is transparent to wavelength 300nm light;
OD300 blocks all wavelength-300nm light, lets through 25% of 350nm and 250nm light, and is transparent to wavelength 400nm and 200nm light;
OD400 blocks all wavelength-400nm light, lets through 25% of 450nm and 350nm light, and is transparent to wavelength 500nm and 300nm light;
OD500 blocks all wavelength-500nm light, lets through 25% of 550nm and 450nm light, and is transparent to wavelength 600nm and 400nm light;
OD600 blocks all wavelength-600nm light, lets through 25% of 650nm and 550nm light, and is transparent to wavelength 700nm and 500nm light;
OD700 blocks all wavelength-700nm light, lets through 25% of 750nm and 650nm light, and is transparent to wavelength 600nm light.
Now, in addition to each visual pigment without any oil-drops, we could also have:
Spoiler:
VP300 with OD200
VP300 with OD400
VP400 with OD300
VP400 with OD500
VP500 with OD400
VP500 with OD600
VP600 with OD500
VP600 with OD700
VP700 with OD600.
For instance, the cones that respond to light in wavelengths between 450nm and 550nm are:
Spoiler:
VP400 w OD500
VP400 w/o oil
VP400 w OD300
VP500 w OD600
VP500 w/o oil
VP500 w OD400
VP600 w OD700
VP600 w/o oil
VP600 w OD500
Because OD300 is transparent to wavelengths 400nm and longer its presence or absence makes no difference to the response of the VP400-bearing cones to light in the 450nm-to-550nm range, provided those cones don't have the OD500 droplets.
Similarly, because OD700 is transparent to wavelengths 600nm and shorter its presence or absence makes no difference to the response of the VP600-bearing cones to light in the 450-to-550nm range, provided those cones don't have the OD500 droplets.

So let's look at some wavelengths.

Suppose we represent the responses by ordered 7-tuplets of percentages of peak response, in the order
Spoiler:
VP400 with OD500
VP400 without oil
VP500 with OD600
VP500 without oil
VP500 with OD400
VP600 without oil
VP600 with OD500
450nm gets (19%, 75%, 75%, 75%, 19%, 0%, 0%)
460nm gets (12%, 60%, 80%, 80%, 32%, 0%, 0%)
480nm gets (3%, 30%, 90%, 90%, 63%, 0%, 0%)
500nm gets (0%, 0%, 100%, 100%, 100%, 0%, 0%)
520nm gets (0%, 0%, 63%, 90%, 90%, 30%, 3%)
540nm gets (0%, 0%, 32%, 80%, 80%, 60%, 12%)
550nm gets (0%, 0%, 19%, 75%, 75%, 75%, 19%)

No linear combination of 450nm and 500nm and 550nm, can add up to mimicking any of 460nm, 480nm, 520nm, or 540nm.
Spoiler:
At 450nm,
the VP400 and VP500 cones without oil and the VP500-with-OD600 cones respond at 75%;
the VP400-with-OD500 cones and the VP500-with-OD400 cones respond at 19%;
the other cones don't respond.

At 460nm,
the VP500-without-oil and the VP500-with-OD600 cones respond at 80%;
the VP400-without-oil cones respond at 60%;
the VP500-with-OD400 cones respond at 32%;
the VP400-with-OD500 cones respond at 12%;
the other cones don't respond.

At 480nm,
the VP500-without-oil and the VP500-with-OD600 cones respond at 90%;
the VP500-with-OD400 cones respond at 63%;
the VP400-without-oil cones respond at 40%;
the VP400-with-OD500 cones respond at 3%;
the other cones don't respond.

At 500nm,
the VP500 cones, whether without oil or with OD400 or with OD600, all respond at 100%;
the other cones don't respond.

At 520nm,
the VP500-without-oil and VP500-with-OD400 cones respond at 90%;
the VP500-with-OD600 cones respond at 63%;
the VP600-without-oil cones respond at 30%;
the VP600-with-OD500 cones respond at 3%;
the other cones don't respond.

At 540nm,
the VP500-without-oil and VP500-with-OD400 cones respond at 80%;
the VP600-without-oil cones respond at 60%;
the VP500-with-OD600 cones respond at 32%;
the VP600-with-OD500 cones respond at 12%;
the other cones don't respond.

At 550nm,
the VP600 and VP500 cones without oil the VP500-with-OD400 cones respond at 75%;
the VP500-with-OD600 cones and the VP600-with-OD500 cones respond at 19%;
the other cones don't respond.
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Re: Color perception of your con-species

Post by Micamo »

In particular they sometimes need to be able to tell the difference between, on the one hand, a mix of two wavelengths, and, on the other hand, a single wavelength, when without the oil-droplets they couldn't do that.
Wow! That was a really helpful explanation. You're so awesome!
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Re: Color perception of your con-species

Post by Tanni »

eldin raigmore wrote:
Micamo wrote:I'm not sure yet whether I want to have the oil droplets, I'm having trouble finding information on exactly what they do for color perception.
They help the perceiver distinguish between different mixes of wavelengths.

For instance, suppose you have two photo-reactive photo-sensitive visual pigments, VP500 and VP600.

Suppose VP500 reacts at:
100% to wavelength 500 nm,
Spoiler:
95% to wavelengths 510 nm or 490 nm,
90% to wavelengths 520 nm or 480 nm,
85% to wavelengths 530 nm or 470 nm,
80% to wavelengths 540 nm or 460 nm,
75% to wavelengths 550 nm or 450 nm,
Spoiler:
60% to wavelengths 560 nm or 440 nm,
45% to wavelengths 570 nm or 430 nm,
30% to wavelengths 580 nm or 420 nm,
15% to wavelengths 590 nm or 410 nm,
0% to wavelengths 600 nm or longer or 400 nm or shorter.

Similarly, suppose VP600 reacts at:
100% to wavelength 600 nm,
Spoiler:
90% to wavelengths 620 nm or 580 nm,
80% to wavelengths 640 nm or 560 nm,
75% to wavelengths 650 nm or 550 nm,
Spoiler:
60% to wavelengths 660 nm or 540 nm,
30% to wavelengths 680 nm or 520 nm,
0% to wavelengths 700 nm or longer or 500 nm or shorter.

If the only chromoceptors stimulated by wavelengths between 500nm and 600nm are VP500 and VP600, then the light at any single wavelength between 500nm and 600nm can be mimicked by a mixture of light at 500nm with light at 600nm.

For instance,
100 photons at 550 nm could be mimicked by 75 photons at 500nm with 75 photons at 600nm;
because light at 550nm makes both the VP500 cones and the VP600 cones respond at 75%.

For more instances,
Spoiler:
100 photons at 520 nm could be mimicked by 90 photons at 500nm with 30 photons at 600nm;
100 photons at 540 nm could be mimicked by 80 photons at 500nm with 60 photons at 600nm;
100 photons at 560 nm could be mimicked by 60 photons at 500nm with 80 photons at 600nm;
100 photons at 580 nm could be mimicked by 30 photons at 500nm with 90 photons at 600nm.
But now, suppose you also had differentially-opaque/differentially-transparent droplets of oils, OD500 and OD600.

Suppose OD500 lets through;
0% of the light at a wavelength of 500nm,
Spoiler:
5% of the light at wavelengths of 510nm and 490 nm,
10% of the light at wavelengths of 520nm and 480 nm,
15% of the light at wavelengths of 530nm and 470 nm,
20% of the light at wavelengths of 540nm and 460 nm,
25% of the light at wavelengths of 550nm and 450 nm,
Spoiler:
40% of the light at wavelengths of 560nm and 440 nm,
55% of the light at wavelengths of 570nm and 430 nm,
70% of the light at wavelengths of 580nm and 420 nm,
85% of the light at wavelengths of 590nm and 410 nm,
100% of the light at wavelengths of 600nm or longer and 400 nm or shorter.

Similarly, suppose OD600 lets through;
0% of the light at a wavelength of 600nm,
Spoiler:
10% of the light at wavelengths of 620nm and 580 nm,
20% of the light at wavelengths of 640nm and 560 nm,
25% of the light at wavelengths of 650nm and 550 nm,
Spoiler:
40% of the light at wavelengths of 660nm and 540 nm,
70% of the light at wavelengths of 680nm and 520 nm,
100% of the light at wavelengths of 700nm or longer and 500 nm or shorter.

Now suppose you have four types of cones that respond to wavelengths of 500nm to 600nm, instead of only two:
VP500 cones without oil-droplets,
VP500 cones with OD600 oil-droplets,
VP600 cones without oil-droplets,
and VP600 cones with OD500 oil-droplets.

Now, light at 550nm makes the VP500-without-oil cones and the VP600-without-oil cones both respond at 75%; but the VP500-with-OD600 cones and the VP600-with-OD500 cones both respond at 18.75% (about 19%).
Light at a wavelength of 500nm always equally stimulates the VP500-without-oil cones and the VP500-with-OD600 cones equally, and always fails to stimulate both the VP600-without-oil cones and the VP600-with-OD500 cones.
Likewise, light at a wavelength of 600nm always equally stimulates the VP600-without-oil cones and the VP600-with-OD500 cones equally, and always fails to stimulate both the VP500-without-oil cones and the VP500-with-OD600 cones.
So any mix of wavelength-500nm light with wavelength-600nm light will get the same reaction from the VP500 cones whether or not they have an oil-droplet, and will get the same reaction from the VP600 cones whether or not they have an oil-droplet.
No single-wavelength light in the range of 500nm to 600nm can be mimicked by any mixture of two other wavelengths in that range.

Apparently many birds who have cones with oil-droplets need to be able to differentiate "colors" in the oranges-and-yellows better than cones without oil-droplets would enable them to do. In particular they sometimes need to be able to tell the difference between, on the one hand, a mix of two wavelengths, and, on the other hand, a single wavelength, when without the oil-droplets they couldn't do that.

_______________________________________________________________________________

Suppose you had visual pigments VP200, VP300, VP400, VP500, VP600, and VP700.
Suppose:
Spoiler:
VP200 responds at 100% to 200nm, at 75% to 250nm, and at 0% to 300nm;
VP300 responds at 100% to 300nm, at 75% to 350nm or 250nm, and at 0% to 400nm or 200nm;
VP400 responds at 100% to 400nm, at 75% to 450nm or 350nm, and at 0% to 500nm or 300nm;
VP500 responds at 100% to 500nm, at 75% to 550nm or 450nm, and at 0% to 600nm or 400nm;
VP600 responds at 100% to 600nm, at 75% to 650nm or 550nm, and at 0% to 700nm or 500nm;
VP700 responds at 100% to 700nm, at 75% to 750nm or 650nm, and at 0% to 800nm or 600nm.
If there are no oil-droplets, the VP400 cones by themselves can't tell the difference between wavelength 350nm light and wavelength 450nm light; VP400 cones respond at 75% to both of those wavelengths. But 450nm light stimulates the VP500 cones too, whereas 350nm light does not.

If, between the peak-response wavelengths of any two visual pigments, one finds a range of wavelengths to which only those two pigments respond, then any single wavelength in the interior of that range can be imitated by a mix of two other wavelengths in that range, and any mix of any two wavelengths in that range can be mimicked by some single wavelength in that range.

But if we had oil-droplets OD200, OD300, OD400, OD500, OD600, and OD700, such that:
Spoiler:
OD200 blocks all wavelength-200nm light, lets through 25% of 250nm light, and is transparent to wavelength 300nm light;
OD300 blocks all wavelength-300nm light, lets through 25% of 350nm and 250nm light, and is transparent to wavelength 400nm and 200nm light;
OD400 blocks all wavelength-400nm light, lets through 25% of 450nm and 350nm light, and is transparent to wavelength 500nm and 300nm light;
OD500 blocks all wavelength-500nm light, lets through 25% of 550nm and 450nm light, and is transparent to wavelength 600nm and 400nm light;
OD600 blocks all wavelength-600nm light, lets through 25% of 650nm and 550nm light, and is transparent to wavelength 700nm and 500nm light;
OD700 blocks all wavelength-700nm light, lets through 25% of 750nm and 650nm light, and is transparent to wavelength 600nm light.
Now, in addition to each visual pigment without any oil-drops, we could also have:
Spoiler:
VP300 with OD200
VP300 with OD400
VP400 with OD300
VP400 with OD500
VP500 with OD400
VP500 with OD600
VP600 with OD500
VP600 with OD700
VP700 with OD600.
For instance, the cones that respond to light in wavelengths between 450nm and 550nm are:
Spoiler:
VP400 w OD500
VP400 w/o oil
VP400 w OD300
VP500 w OD600
VP500 w/o oil
VP500 w OD400
VP600 w OD700
VP600 w/o oil
VP600 w OD500
Because OD300 is transparent to wavelengths 400nm and longer its presence or absence makes no difference to the response of the VP400-bearing cones to light in the 450nm-to-550nm range, provided those cones don't have the OD500 droplets.
Similarly, because OD700 is transparent to wavelengths 600nm and shorter its presence or absence makes no difference to the response of the VP600-bearing cones to light in the 450-to-550nm range, provided those cones don't have the OD500 droplets.

So let's look at some wavelengths.

Suppose we represent the responses by ordered 7-tuplets of percentages of peak response, in the order
Spoiler:
VP400 with OD500
VP400 without oil
VP500 with OD600
VP500 without oil
VP500 with OD400
VP600 without oil
VP600 with OD500
450nm gets (19%, 75%, 75%, 75%, 19%, 0%, 0%)
460nm gets (12%, 60%, 80%, 80%, 32%, 0%, 0%)
480nm gets (3%, 30%, 90%, 90%, 63%, 0%, 0%)
500nm gets (0%, 0%, 100%, 100%, 100%, 0%, 0%)
520nm gets (0%, 0%, 63%, 90%, 90%, 30%, 3%)
540nm gets (0%, 0%, 32%, 80%, 80%, 60%, 12%)
550nm gets (0%, 0%, 19%, 75%, 75%, 75%, 19%)

No linear combination of 450nm and 500nm and 550nm, can add up to mimicking any of 460nm, 480nm, 520nm, or 540nm.
Spoiler:
At 450nm,
the VP400 and VP500 cones without oil and the VP500-with-OD600 cones respond at 75%;
the VP400-with-OD500 cones and the VP500-with-OD400 cones respond at 19%;
the other cones don't respond.

At 460nm,
the VP500-without-oil and the VP500-with-OD600 cones respond at 80%;
the VP400-without-oil cones respond at 60%;
the VP500-with-OD400 cones respond at 32%;
the VP400-with-OD500 cones respond at 12%;
the other cones don't respond.

At 480nm,
the VP500-without-oil and the VP500-with-OD600 cones respond at 90%;
the VP500-with-OD400 cones respond at 63%;
the VP400-without-oil cones respond at 40%;
the VP400-with-OD500 cones respond at 3%;
the other cones don't respond.

At 500nm,
the VP500 cones, whether without oil or with OD400 or with OD600, all respond at 100%;
the other cones don't respond.

At 520nm,
the VP500-without-oil and VP500-with-OD400 cones respond at 90%;
the VP500-with-OD600 cones respond at 63%;
the VP600-without-oil cones respond at 30%;
the VP600-with-OD500 cones respond at 3%;
the other cones don't respond.

At 540nm,
the VP500-without-oil and VP500-with-OD400 cones respond at 80%;
the VP600-without-oil cones respond at 60%;
the VP500-with-OD600 cones respond at 32%;
the VP600-with-OD500 cones respond at 12%;
the other cones don't respond.

At 550nm,
the VP600 and VP500 cones without oil the VP500-with-OD400 cones respond at 75%;
the VP500-with-OD600 cones and the VP600-with-OD500 cones respond at 19%;
the other cones don't respond.
Eldin, can you explain that in a few simple words?
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Re: Color perception of your con-species

Post by eldin raigmore »

Tanni wrote:Eldin, can you explain that in a few simple words?
Probably could, by leaving out most of the words in my previous post; but I don't know exactly which ones to leave out, and expect I'd have trouble deciding.
Since Micamo understands what I said, maybe Micamo can rephrase it in shorter and/or simpler form?
@Micamo; care to give it a try?
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Re: Color perception of your con-species

Post by Micamo »

Basically the oil droplets change the cone response function to no longer be "linear." In humans, photons with different wavelengths can be mistaken for photons of a single wavelength, where the "blended" color is a sort of average of the different wavelengths. The oil droplets make it so the creature can differentiate between, e.g., 400 nm + 500 nm and 450 nm.
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Re: Color perception of your con-species

Post by Ear of the Sphinx »

Basically the oil droplets change the cone response function to no longer be "linear." In humans, photons with different wavelengths can be mistaken for photons of a single wavelength, where the "blended" color is a sort of average of the different wavelengths. The oil droplets make it so the creature can differentiate between, e.g., 400 nm + 500 nm and 450 nm.
Yhm.
In other words, we see RGB. Yellow is a mixture of red and green for us, so we can replace yellow with red-green e.g. in construction of screens. If there was a creature seeing in RYGB, it would see yellow and red-green different, as we see green and red-blue different.
But that's possible there are humans that can see four basic colours. And there are some RYGB screens produced.
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Re: Color perception of your con-species

Post by Bristel »

It would be cool to be a tetrachromat...

I wonder if that is another reason birds can see small animals from a distance... by discerning color differences that humans and other animals cannot.
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