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I don't see why seeing an extended pallet in dreams would be a thing particular to tetrachromats. Unless trichromatic vision completely covers the gamut of natu

I don't see why seeing an extended pallet in dreams would be a thing particular to tetrachromats. Unless trichromatic vision completely covers the gamut of naturally occuring wavelength combinations, which I doubt.

eru 7y ago
What do naturally occurring wavelength combinations have to do with what happens in your dreams?
ajross 7y ago
That's not quite the right way to think about it. Obviously, existing vision "covers" the full spectrum, there aren't any wavelengths that we can't see. The trick to impossible colors is recognizing that our existing receptor spectra overlap. It's not possible to get "100% red" in the sense of only the "red" cone cells firing and none of the "blue" or "green" ones, because those other cells are going to fire at some small rate for the same frequencies. But our brain can certainly receive such a color even if our eyes don't produce it, so in some sense we "understand" it as a color even if we'll never see it outside a laboratory or hallucination.
- JimboOmega 7y ago
  I think you and the other person are referring to two different "spectrums". Our vision covers a tiny portion of the EM spectrum, for instance, we can't see infrared, microwave, gamma, x-ray, etc. There are separately colors which we are wired to hypothetically receive, as you point out (and I find interesting) - IE, if you replace the eye with some sort of artificial replacement, then such a signal could get received by the brain, but with the current sensors it is impossible (also, I suppose a colorblind person could receive such a signal as 100% red without the other colors). There's also the possibility during a dream of creating objects or sensations that are not physically possible. For instance, I've had dreams where I had a form of telekinesis, and obviously there's no sort of brain wiring to manipulate physical objects outside of the normal motor functions. Still, it made sense in the dream - and it's not like I could describe how I did it, and it's not because the hardware exists but the sensor doesn't. Although - you could argue that there's a layer of abstraction in the brain of such things in the brain - for instance, when I'm typing these words I don't actually ever have any conscious awareness of my finger motions. I don't even think about the act of typing at all; only the words. So, thinking about it, the brain does have an idea of manipulating objects outside of a need for muscles to do it. I would think for a tetrachromat the abstract sensation of seeing colors you can't describe to others is itself a familiar one, and that feeling itself is something you might encounter in dreams. My dreams tend to start with a feeling, and then build a context for it. Tl;dr - dreams are weird.
OscarCunningham 7y ago
The space of wavelength combinations is infinite-dimensional, so it's not going to be covered by vision using any finite number of types of cones.
- arketyp 7y ago
  That’s why I said naturally occurring. If naturally occurring colors corresponds approximately 1-to-1 with trichromatic vision, that could explaining why a tetrachromat dreams of unreal colors and trichromats don’t.
roywiggins 7y ago
Colors like magenta (red and blue wavelengths together) are nonspectral, having no single wavelength they correspond to. They only exist as a mix, and we see a pinkish color that you can't write down as a wavelength. Tetrachromats could plausibly see more nonspectral colors by activating their extra color receptor and one of the other ones. There would be no exact equivalent in trichromatic vision. It depends on what their brains decide to do with it- maybe they would just land on an existing color in between. But there's no reason it has to. So these colors are something that tetrachromats could maybe see while awake, but usually with lots of other colors mixed in. Asleep, maybe the brain starts to play with them and generates pure versions of them. Trichromats wouldn't be very likely to have these dreams because their brains don't have experience of tetrachromat nonspectral colors at all.
- arketyp 7y ago
  That has nothing to do with my argument. Why would tetrachromats be inclined to dream of colors they do not see in the real world any more than trichromats?
  - roywiggins 7y ago
    My point is they would see those colors in the real world, but only in combination with other colors, so it wouldn't be that noticable. They wouldn't see pure versions of them much, if at all. The intensity in a dream might be much stronger, enough that it would seem like a qualitatively new color rather than "hmm, that blue has something different going on compared to other blues" they you might get in real life. You could put them in front of light source that generated pure wavelengths designed to selectively activate their extra cone and ask what they see when you start mixing pure blue or green into it. Maybe they'd recognize those colors from their dreams, maybe not. I don't know. But it's a mechanism that would explain how tetrachromats might dream colors that trichromats don't.
    - arketyp 7y ago
      But this assumes the gamut of trichromacy is more anchored in reality (woken life) than the gamut of tetrachromacy. In principle there is nothing different between a trichromat and a tetrachromat sense of color. They see one dimension of color more, just like humans see one dimension more than dogs.
pharrington 7y ago
Dreams are recombinations of a nervous system's existing sense data.
Barrin92 7y ago
probably because exposure to the sensory information is required to be reproduced in dreams. People who are born deaf don't hear sounds in dreams either.

eru 7y ago

What do naturally occurring wavelength combinations have to do with what happens in your dreams?

ajross 7y ago

That's not quite the right way to think about it. Obviously, existing vision "covers" the full spectrum, there aren't any wavelengths that we can't see. The trick to impossible colors is recognizing that our existing receptor spectra overlap. It's not possible to get "100% red" in the sense of only the "red" cone cells firing and none of the "blue" or "green" ones, because those other cells are going to fire at some small rate for the same frequencies. But our brain can certainly receive such a color even if our eyes don't produce it, so in some sense we "understand" it as a color even if we'll never see it outside a laboratory or hallucination.

JimboOmega 7y ago
I think you and the other person are referring to two different "spectrums". Our vision covers a tiny portion of the EM spectrum, for instance, we can't see infrared, microwave, gamma, x-ray, etc. There are separately colors which we are wired to hypothetically receive, as you point out (and I find interesting) - IE, if you replace the eye with some sort of artificial replacement, then such a signal could get received by the brain, but with the current sensors it is impossible (also, I suppose a colorblind person could receive such a signal as 100% red without the other colors). There's also the possibility during a dream of creating objects or sensations that are not physically possible. For instance, I've had dreams where I had a form of telekinesis, and obviously there's no sort of brain wiring to manipulate physical objects outside of the normal motor functions. Still, it made sense in the dream - and it's not like I could describe how I did it, and it's not because the hardware exists but the sensor doesn't. Although - you could argue that there's a layer of abstraction in the brain of such things in the brain - for instance, when I'm typing these words I don't actually ever have any conscious awareness of my finger motions. I don't even think about the act of typing at all; only the words. So, thinking about it, the brain does have an idea of manipulating objects outside of a need for muscles to do it. I would think for a tetrachromat the abstract sensation of seeing colors you can't describe to others is itself a familiar one, and that feeling itself is something you might encounter in dreams. My dreams tend to start with a feeling, and then build a context for it. Tl;dr - dreams are weird.

OscarCunningham 7y ago

The space of wavelength combinations is infinite-dimensional, so it's not going to be covered by vision using any finite number of types of cones.

arketyp 7y ago
That’s why I said naturally occurring. If naturally occurring colors corresponds approximately 1-to-1 with trichromatic vision, that could explaining why a tetrachromat dreams of unreal colors and trichromats don’t.

roywiggins 7y ago

Colors like magenta (red and blue wavelengths together) are nonspectral, having no single wavelength they correspond to. They only exist as a mix, and we see a pinkish color that you can't write down as a wavelength. Tetrachromats could plausibly see more nonspectral colors by activating their extra color receptor and one of the other ones. There would be no exact equivalent in trichromatic vision. It depends on what their brains decide to do with it- maybe they would just land on an existing color in between. But there's no reason it has to. So these colors are something that tetrachromats could maybe see while awake, but usually with lots of other colors mixed in. Asleep, maybe the brain starts to play with them and generates pure versions of them. Trichromats wouldn't be very likely to have these dreams because their brains don't have experience of tetrachromat nonspectral colors at all.

arketyp 7y ago
That has nothing to do with my argument. Why would tetrachromats be inclined to dream of colors they do not see in the real world any more than trichromats?
- roywiggins 7y ago
  My point is they would see those colors in the real world, but only in combination with other colors, so it wouldn't be that noticable. They wouldn't see pure versions of them much, if at all. The intensity in a dream might be much stronger, enough that it would seem like a qualitatively new color rather than "hmm, that blue has something different going on compared to other blues" they you might get in real life. You could put them in front of light source that generated pure wavelengths designed to selectively activate their extra cone and ask what they see when you start mixing pure blue or green into it. Maybe they'd recognize those colors from their dreams, maybe not. I don't know. But it's a mechanism that would explain how tetrachromats might dream colors that trichromats don't.
  - arketyp 7y ago
    But this assumes the gamut of trichromacy is more anchored in reality (woken life) than the gamut of tetrachromacy. In principle there is nothing different between a trichromat and a tetrachromat sense of color. They see one dimension of color more, just like humans see one dimension more than dogs.

pharrington 7y ago

Dreams are recombinations of a nervous system's existing sense data.

Barrin92 7y ago

probably because exposure to the sensory information is required to be reproduced in dreams. People who are born deaf don't hear sounds in dreams either.