The first sense of colours isn’t like the second sense of colours. The second sense of colours refers to the qualitative character of first-person visual experience, and this qualitative character is nothing like the microstructural properties that cause an object to reflect a certain wavelength of light.
Given the biological differences between two different organisms (e.g. of different species), it’s possible that the colour experience of one observer is radically different to the colour experience of another observer (e.g. as in the inverted spectrum hypothesis) when looking at the same object, and it makes no sense to say that one or the other is seeing the object’s “actual” colour and the other is seeing the “wrong” colour.
And when the OP says that we can be made to see “novel colours” they are referring to colours in the sense of the phenomenal character of first-person visual experience, not to the microstructural properties that cause an object to reflect a certain wavelength of light.
Well, you said “with the [causal] link, you see the object’s actual colours” which seems to be an endorsement of naive colour primitivism.
If instead by “see the object’s actual colours” you only mean “the object’s microstructural properties are causally responsible for the colour experience” then you are simply asserting the vacuous tautology that when the object’s microstructural properties are causally responsible for the colour experience, the object’s microstructural properties are causally responsible for the colour experience.
After distinguishing perceptual experiences (you see their cause) from hallucinatory experiences (you don’t see their cause), it seems to me that the colour experience evoked by the lasers is hallucinatory (you see an image but its colours are elicited by stuff you don’t see (the process of lasers stimulating individual cells in the eye).
Thus the colour experience is detached from the object of the experience (the image). But that’s also how it is possible to enhance colours or elicit entirely new colours.
– ressurecting a slight zombie thread to reply to this; hope it’s not bad form –
I’m not seeing a useful distinction though.
Consider this example: I touch a hot stove, and feel pain. Now, “pain” and “heat” are not the same thing. Pain is a subjective experience made by brain. There is no “pain” in or on the stove.
So if we say that that experience is “real”, because I can see what caused me to feel pain, well I can also see what caused me to see “schellow”.
I think it’s useful to distinguish between hallucinations and ordinary experiences.
When you see a green pigment or green light, you see the object of your colour experience. When the laser stimulates select cones inside the eye, it might elicit a similar colour experience. But then you only have the experience without seeing its object (i.e. your visual field is green, but there is no green light nor green pigment, hence colour hallucination).
Pain is not a visual experience, so we have no reason to expect to see a visible object that causes the pain. It’s a warning signal about potential damage or injury in some body part.
An experience is as real as a molecule or money. The experience exists only for the observer who has it. Money exists only for users who agree that it exists. A molecule exist independent of observers or users. All three are real, but have different modes of existing.
So it is not whether particular frequencies of light have struck the retina but the relation to objects that make something a hallucination?
It’s a very non-standard definition of “hallucination”.
Most people would not say I hallucinated an apple if, say, I saw an apple on TV. If I wrongly interpreted what I was seeing, and believed there really was an apple inside my living room, then we can talk (though I would still not say “hallucination” is the right word for an erroneous interpretation).
I wasn’t talking about seeing; it’s an illustration that subjective experience need not have any relation to a property of the object itself.
In fact the same is true with vision too – frequencies of EM radiation, and the subjective experience of colour are two different things. However, they are so seamlessly coupled so much of the time for most of us, that many people assume that colour is actually “out there” in the world. That’s why pain is a better sense to use to illustrate the point.
Hallucinations are experiences of things that are not real. That’s why they’re called hallucinations.
The technology described in the article doesn’t even resemble the frequencies of light that strike the retina under ordinary colour vision. It is a laser that selectively manipulates individual cells in the eye.
It doesn’t even need to have the colour that corresponds to the experience that it elicits.
No-one says seeing an apple on TV is to hallucinate an apple.
Interpretations can indeed be right or wrong, but perceptions are neither. A perception is a response to something that your sense organs make you consciously aware of. How you respond to a taste is influenced by the ingredients, context, state of your mind, taste buds, previous habits etc. What you do with it, or how you interpret it, is a function of interest.
It need not have any relation to an object either, such as in hallucinations (or solipsism).
Indeed, light is one of the conditions under which ordinary colour experiences are satisfied. In the dark, a drug or a laser might elicit phenomenally identical experiences, but they’re hallucinations.
Some pains might not have objects of perception (?), but visual experiences do. Such as these scribbles that we both perceive and interpret according to the rules of a shared language. Are these words and colours not published out there?
I still don’t follow how this is consistent. Maybe you can clarify?
I’ll say first what I would call a hallucination…
I’d say, ignoring solipsism for now (as we often have to), that any time I am seeing something because cells on my retina are being activated by photons from the outside world, then I am seeing, and not hallucinating. And that this seeing is separate from the question of how I interpret what I am seeing.
So neither watching TV nor having a laser shot into my eye is hallucinating.
What is your definition of hallucination, and why does the laser count but watching TV does not?
Colour isn’t out there, no.
For an example, I’ll use TV again:
The wavelength of “yellow light” is about 570 to 590nm.
So, if you’re seeing a bright yellow banana on TV, how many 570-590nm photons are striking your retina? The answer is zero (from the TV at least).
Someone sat closer to the TV can verify that there are only green and red subpixels lit up. And we know from physics that red and green photons pass through each other – in no sense do they combine or mix “out there” and somehow make a 580nm photon…that’s not a thing.
So where is the yellow?
And hopefully a bit of introspection will reveal that it is always this way…even if light of the “right” frequency was being shone into your eyes, your brain is still the place where that gets converted into the subjective experience that we call colour (or color).
What could “photons from the outside world” look like?
I imagine an empty visual field, yet somehow, out of nowhere, there’s a bundle of photons whose frequencies fill the visual field with coloured light… But how could that be possible without seeing, e.g. surfaces on which the light could scatter and become visible?
You are selectively thinking of photons activating cells in your eyes, but vision is more complex than that.
And why would you want visual experiences to be like hallucinations or pains?
Out there, evoked by the green and red subpixels. Remove the subpixels and also the yellow disappears.
Colours have complex modes of existing. In biology, that’s not uncommon.
"… Being complex and of no interest to fundamental physics isn’t a failure to be “real”. I think green is as real as applehood.”
-Hilary Putnam (from a blog post on Naive Realism and Colour Realism"
Firstly, I said that colour happens in the brain, so the question is based on mischaracterizing my position and/or I don’t agree with the premise.
Secondly, I asked first: how are you defining hallucination, and why does the laser count as one and a TV does not?
Out there where?
Bear in mind, as I say, someone sat closer to the screen can see discrete red and green subpixels. So this “evocation” isn’t happening on the screen.
How do you get from “evoked by” to “exists out there”?
Say we have a machine that detects photons and displays some associated word on a screen, like “foo” or “bar”, determined by the wavelength.
The word “foo” on the screen is evoked by the photons, and disappears if the light is turned off, but doesn’t exist “out there” in either the light or its source. It only exists on the machine’s screen.
The claim being made is that colours are like the words on the screen. They are a biological/mental phenomenon, causally determined by the photons striking our retinas, but distinct from both the light and its source. The naive realist’s claim that these colours exist “out there (beyond the body)” is as mistaken as the claim that the word “foo” exists “out there (beyond the machine)”.
The question is based on your exact description of the causal chain, not your position.
All experiences happen in the brain, at least in their constituitive sense. The object of an experience, however, is outside the experience, and the objects of most perceptual experiences are located outside the brain, in other body parts or in the environment.
In a previous post I explain the difference between hallucination and experience.
The laser-elicited experience counts as hallucination since the object of the experience is missing. You don’t see the manipulation of individual cells in your visual field. Instead you have a controlled hallucination which exploits existing capacities for colour vision.
The TV-image of a red apple, however, is a visible object of the experience. The colour of the apple is its real disposition to be seen as red
I think it’s obviously true that the objects and states of affairs of visual experience are located in front of our eyes.
I see no good reason to reinterpret the apple as if it was a colourless swarm of atoms whose properties happen elsewhere, in different brains.
In the same sense higher level phenomena (e.g. yellow) emerge from their lower level parts (green and red subpixels).
The subpixels exist out there, and I see no good reason to detach them from their experiences. You would have to be a dualist or eliminativist to want to do that.
The red and green subpixels have a disposition to be seen as red and green from nearby, and as yellow from a distance. This is not unlike Earth’s surface appearing mountaneous from nearby and smooth from far away.
I don’t understand how that relates to colour vision as we know it from natural examples.
Our eyes contain S-cones, M-cones, and L-cones (and rods). These cells release a constant stream of glutamate. When these cells absorb photons this release of glutamate is reduced, proportional to the “sensitivity” of the cells to the particular wavelength, as represented by this graph:
It is the ratio of glutamate released by the cone cells that determines the colour seen, and is why those with more types of cone cells (e.g. tetrachromacy), fewer types of cone cells (e.g. dichromacy), or cone cells with a sensitivity range that differs from that above see different colours when looking at the same things or the same light (and none of these groups are seeing either the “right” or the “wrong” colours).
Neither 700nm light nor things which reflect 700nm light are coloured red; it’s just that most humans have cone cells that react to 700nm light in such a way that a red colour experience is elicited.
Or, it is the right kind of stimulation in certain parts of the brain that determines the colour seen.
Or as I’d say, it is the right kind of pigment in the object out there that determines the frequencies of the photons, the biochemical process in the eye, the ratio of glutamate, the brain event, and colour seen.
Your claim is true but selective. My claim is also true, and includes your claim.
That’s right, because a colour experience doesn’t represent another “real” colour. They’re all equally real.
In the case of a colour hallucination (e.g. elicited by a drug, fatigue, lasers etc), the experience is real, but what you see is not a real colour. That’s why it’s called hallucination.
I was referring specifically to the case of the red and green pixels “adding” together to make yellow. This isn’t something that happens on the TV or in the air between the TV and us; it’s something that happens in the eye, and so it’s wrong to say that the yellow colour we see exists “out there” as some “higher-level emergent phenomenon”.
I’m not sure what you think I’m saying.
I’m saying that photons have many different physical properties, like rest mass, polarization, and wavelength. None of these properties are colours, and a red colour is not some additional property that 700nm light possesses.
I’m saying that apples have many different physical properties, like chemical composition and the arrangement of electrons on its surface. None of these properties are colours, and a red colour is not some additional property that a surface that reflects 700nm light possesses.
I’m saying that colours, like pain, are a mental phenomenon (which may be reducible to a neurological phenomenon). Particular colour experiences are usually explained by particular wavelengths of light stimulating the cone cells in our eyes, and particular wavelengths of light are usually explained by particular arrangements of electrons on an apple’s surface, and it might seem as if these colours are inherent properties of either the light or the apple’s surface (which is why naive colour primitivism is a thing), but the colours are just the mental phenomenon.
These colours are as real as anything else in the universe, they’re just not located where the naive realist says they are (in the light or on the apple’s surface).
Consider the red and green pixels on the TV-screen. They’re specifically engineered to have a disposition to be seen together as yellow from a distance. The disposition is real and directly related to the eye-event and the rest of the visual system. Saying that the colours are out there does not omit the eye-event.
What happens in the eye and brain is the seeing. The colours that we see, however, are where they manifest: e.g. on the TV-screen.
Yes, but is not what is being discussed. We’re discussing colour, not dispositions to be seen as a colour. Colours are not dispositions to be seen as a colour. Or, at the very least, given the sentence “to be red is to be disposed to be seen as red”, the second use of the word “red” does not refer to a disposition, else you end up with the recursive sentence “to be red is to be disposed to be seen as disposed to be seen as disposed…”.
Our concern is the nature of the thing referred to by the second use of the word “red” in that sentence; that qualitative characteristic present in visual experience. The naive colour primitivist incorrectly claims it to be an inherent property of light and/or material surfaces, like their mass or wavelength or molecular composition, and the subjectivist correctly claims it to be a mental(/neurological) phenomenon.
It doesn’t “manifest” on the TV screen; the screen just emits FF0000 and 00FF00 light (to use hex values instead of wavelengths). The yellow colour “manifests” in the human body/mind, and only seems to be located on the TV screen, but how this seems isn’t how this is.
not published out there?
That’s a false dichotomy, and disingenious mischaracterization of my position and the words I post.