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Qualia Thought Experiment
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Qualia Thought Experiment

mway
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Posted 07/09/09 - 09:36 PM: Subject: Qualia Thought Experiment	#1
I was thinking about qualia today (again), and I came up with a thought experiment. When you experience colour, the retina is responding to patterns of light, and sending patterns of information to the brain. Lets call all the possible sets of patterns that the retina can send as X. This means when you experience yellow the retina is sending X(yellow) to the brain, etc. Now what if we had a machine that could override the retina, and send what ever pattern we wanted down the optic nerve? Would it be possible to experience colours we have never experienced before by sending new patterns outside of X? Is the colour spectrum (in)finite? Just some ideas. I would also be interested if anyone knew of any such device with which the experiment could be conducted.
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Death Monkey
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Posted 07/10/09 - 02:52 AM:	#2
What color you see is a function of how your visual cortex processes the neural signals coming from the eye. The visual cortex is essentially a very sophisticated pattern-matching machine. The result of this is that if you send signals to your visual cortex that it does not know how to interpret, what you "see" is just whatever the closest approximation it can make. In other words, if you want to be able to see new colors, it is not enough to just send new signals from the eye that represent those new colors. Your visual cortex will have to learn how to interpret those new colors. Just as it would have to learn how to interpret any other changes in the incoming signals, which could be due to any number of factors, such as damage to the optic nerve, changes in the optics of your eye, or whatever. Furthermore, when it comes to conscious experience of seeing color, the parts of your brain responsible for higher cognitive functions also need to learn how to interpret the new information coming from the visual cortex. A sort of example of what you suggest can be found with laser light. You see, ordinarily the cells that are sensitive to red and blue light are also somewhat activated by green light. This means that even when you are seeing pure green light that is exactly at the optimal frequency for your green detector cells, you are still seeing a little bit of blue and red too. You never actually see "pure green", so of course what you think of as "pure green" is actually a little bit washed out. However, by tuning a laser to a multiple of that frequency, which is completely outside of the visible spectrum, it is possible to activate the cells that are sensitive to green light via a non-linear harmonic effect, without activating the red and the green. Do this, and for the first time in your life you will be seeing "pure green". Unfortunately, your poor visual cortex won't know how to interpret the difference. The closest to this "pure green" that it has dealt with is the not-quite-pure green that you normally see. So that is what you will see. You may notice that something is "a bit off", but you won't be able to identify it. Not at first anyway. Given enough time, you could learn to identify the difference. But only then would they actually appear to be different colors. A similar situation occurs with sound. In some languages, the 'r' and 'l' sounds do not exist. Instead, a sound which is somewhat similar to both is commonly used. People from these backgrounds therefore not only have great difficultly pronouncing the 'r' and 'l' sounds, but they also have a hard time hearing the difference. When you say either of the sounds, they hear approximately the same thing. They have to learn how to distinguish the two sounds. DM
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mway
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Posted 07/13/09 - 03:33 PM:	#3
Death Monkey wrote: In other words, if you want to be able to see new colors, it is not enough to just send new signals from the eye that represent those new colors. Your visual cortex will have to learn how to interpret those new colors. Just as it would have to learn how to interpret any other changes in the incoming signals, which could be due to any number of factors, such as damage to the optic nerve, changes in the optics of your eye, or whatever. However, by tuning a laser to a multiple of that frequency, which is completely outside of the visible spectrum, it is possible to activate the cells that are sensitive to green light via a non-linear harmonic effect, without activating the red and the green. Do this, and for the first time in your life you will be seeing "pure green". Rather then a pattern matching machine, the visual cortex works more like heirarchical temporal memory. What you have suggested here is still activating retinal cells, and still producing patterns that lie within X (as I noted above). I am suggesting sending an entirely new set of patterns down the optic nerve. Now if you are correct in saying that the cortex will have to learn to interpret these patterns, then my experiment still applies, you would just need to continue sending new patterns until the cortex 'learnt'. What I would like to know is what colours these new patterns would produce (if any), and what are the extents of the colour spectrum. Obviously (unless you have a new decent theory of qualia), these cannot be answered just yet, but I am interesting in your thoughts regarding how the visual cortex goes from learning patterns, to seeing blue (for example).
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Harbinger
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Posted 07/13/09 - 04:50 PM:	#4
mway wrote: Lets call all the possible [color signals] that the retina can send as X. ... Would it be possible to experience colours we have never experienced before by sending new color signals outside of X? No. If X represents all possible color signals then there is no such thing as a color signal outside of X.
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mway
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Posted 07/13/09 - 08:21 PM:	#5
Harbinger wrote: No. If X represents all possible color signals then there is no such thing as a color signal outside of X. So if you sent a pattern outside of X, what would you see?
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Death Monkey
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Posted 07/14/09 - 12:07 AM:	#6
The visual cortex recieves signals that lie outside of the set of patterns sent by the optic nerve all the time. When it does, you see colors. Ordinary colors. The visual cortex interprets these patterns in terms of what it has been trained to deal with. That's why when strange things happen that cause such abnormal signals to be sent, you see things like spots of color, dancing lights, and so on. Now, if a particular type of signal becomes normal, because it is being sent regularly, then your visual cortex should learn to discriminate that type of signal from the other similar signals that it ordinarily would recieve. I am not completely sure what would happen then, but my suspicion is that you would not begin to experience a new "color sensation", but rather just begin to notice small differences between this new color and the other, similar colors that it originally interpreted it as. As an anology, imagine looking at a computer generated image where the colors are washed out, so that similar colors all end up looking the same. Now imagine the color saturation being slowly corrected, so that the colors become more distinct. I rather suspect that it would be something like that. By the way, this is pretty much what happens with new sounds. Consider the language example I gave before. When I moved to the Netherlands, I discovered that there were certain sounds (specifically vowel combinations) that I had not heard before in English or German. In particular, the sound given by 'ui', such as in the word "huis" (Dutch for house). The pronunciation is very similar to the English pronunciation of "house", but subtly different. The way they pronounce it is a sound I never heard in English, but the difference between it and the pronunciation of "house" is so subtle that, for a while, I could not even hear the difference. I would say "house", and they would say "no, it's 'house'". It would sound exactly the same to me, but to them its sounded different. I could not even begin to learn how to pronounce it properly, because to me it sounds like I was pronouncing it correctly. Likewise, they could say "house" and the "huis", and I would hear no difference. After a while, I began to be able to hear a difference. But it did not qualitatively seem like a new sound to me. Instead, it seemed to me as though people were pronouncing the word differently. It was as though they were originally saying "house", and then gradually began to pronounce it more and more differently, until it became something that now, to me, sounds distinctly different than "house". But it doesn't some like some "new" sound either. Intuitively, it feels to me as though if I had heard the word "huis" three years ago (before I moved here), I would have heard it then the same way that I do now. But I know that this is not the case. I had to learn how to hear it. DM
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mway
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Posted 07/14/09 - 03:42 PM:	#7
So Death Monkey, you are of the opinion that the colour spectrum we know is the only set of colours that exist, and different optic nerve patterns would only improve or alter the clarity of this spectrum? Can you give any examples to your statement, "The visual cortex recieves signals that lie outside of the set of patterns sent by the optic nerve all the time."? With regards to your "house" example, I don't think this applies. The sound that you thought was 'new', still falls within X for all the possible sets of data your ears can send to your brain. The only reason you couldn't distinguish between the two pronounciations is because the brain likes to estimate. A better sound example would be one whereby theoretically you get an upgrade to your ear, so that it can detect frequencies that lie outside the normal hearing spectrum.
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treysuttle
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Posted 07/14/09 - 11:42 PM:	#8
"So if you sent a pattern outside of X, what would you see?" Nothing, mway defined his experiment as 'all possible color patterns'. There are none outside of x. There is no possibility of sending one 'outside of x' if he defines all possible patterns as x. Whether the color spectrum is 'infinite' or not, I think is an empirical question - as such, it cannot be answered with certainty. Just because we reach a point where we never discover a novel color doesn't mean that there was no novel color to be discovered. Yes, I take it that if we were hooked up to such a machine we could experience colors that we have never experienced before. Perhaps our retinas would be stimulated in ways that they have not been stimulated before, which results in our brains cognizing in ways that it has not cognized before. The supposition that recognizing this novel color would be contingent on pattern matching seems irrelevant to me. A color can be a color that I have never seen before...even if I place it somewhere in between blue and green.

Death Monkey
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Posted 07/15/09 - 12:39 AM:	#9
mway, So Death Monkey, you are of the opinion that the colour spectrum we know is the only set of colours that exist, and different optic nerve patterns would only improve or alter the clarity of this spectrum? No, that is not what I am saying. What I am saying is that as you learn to interpret these new signals from your eyes, the subjective experience would change gradually. You would first percieve the new color as just whatever normal color is closest (in the sense of having the most similar signal pattern), and would gradually begin to notice subtle differences. When the learning process is over, you would (probably) not feel as though your color spectrum now included some brand new color, but instead as though you were now more clearly able to distinguish differences between similar colors that you previousl could not percieve. There is no "set of colors that exist". There is only the subjective way that your brain interprets the signals that come to it from your eyes. What you think of as "colors" are just the conceptual labels you attach to those experiences. The ability to "see" the new color just amounts to your brain being able to distinguish between the new signal, and other similar signals that it had already learned how to interpret. As it learns to make this distinction, the subjective experience you have when you see the two colors should gradually change from being the same to just being similar, but noticably different. Can you give any examples to your statement, "The visual cortex recieves signals that lie outside of the set of patterns sent by the optic nerve all the time."? For example, when you bang your head, or when you rub your eyes, or when you are under the influence of certain drugs that alter the sensory signals and/or the way they are processed by the brain. With regards to your "house" example, I don't think this applies. The sound that you thought was 'new', still falls within X for all the possible sets of data your ears can send to your brain. Likewise, there is a set of possible sets of data that your optic nerve can send to your brain. I don't see your point. The issue is that your optic nerve doesn't normally send all of the signals that are possible. Only a subset of them. Anyway, there are only certain characteristics of the input signal that your brain is going to be able to process anyway. You can't just send some arbitrary wave-form and expect it to be distinguished by the brain from some other arbitrary wave-form. The neural hardware of the brain is set up to deal with spike-trains. Send in some arbitrary (non-spike-train) signal, and the brain will just interpret it as whatever spike-train it most closely corresponds to. Furthermore, you have three types of cells in your eyes, each sensitive to a different frequency band. Your brain interprets colors by looking at the firing rates coming from these three types of cells. Each type of cell is neurally connected to parts of the visual centers that interpret the signals they are recieving to represent those colors. So the ability to feed in totally different information from what it is used to is already extremely limited. For example, you could build into the eye a fourth type of cell, sensitive to infrared light. But then what do you wire it up to? You could just wire them up to the brain cells that are currently connected to the red recepters, but then the person will just see everything being a different color. He won't see any new colors. A better thing would be to wire them up to some of the cells that are currently connnected to red receptors, and leave the rest connected to the red receptors. In this case, at first he would just see the infrared light as being red. It would look exactly like normal red to him. But gradually his visual cortex should learn that what used to be a single set of recieving cells is now two different sets. It will learn to make a distinction between the two subsets of cells. So then gradually what seemed to be just one shade of red will begin to look like two different colors. But it won't subjectively seem to be a "new" color. At least, I would not expect it to seem that way. Obviously I can't say for sure. The only reason you couldn't distinguish between the two pronounciations is because the brain likes to estimate. A better sound example would be one whereby theoretically you get an upgrade to your ear, so that it can detect frequencies that lie outside the normal hearing spectrum. Then the situation is analogous to the eye example I gave about. How does your new and improved ear send those signals to the auditory cortex? Your ear breaks the sound down into different frequency bands. Each of those frequency bands then corresponds, again, to a set of cells that connect into the auditory cortex. Rebuild the ear so that now it can detect a new, higher frequency band, and you just end up with a new set of cells that have to be wired into the brain. So where do you wire them to? Wire them in an analogous way to what I described above, and the result should be similar. At first your brain will interpret the sound to be the frequency that corresponds to the reciever cells it is wired to. Over time, it should learn to make a distinction between the two subsets of cells. DM
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Hanover
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Posted 07/15/09 - 04:41 AM:	#10
mway wrote: I was thinking about qualia today (again), and I came up with a thought experiment. When you experience colour, the retina is responding to patterns of light, and sending patterns of information to the brain. Lets call all the possible sets of patterns that the retina can send as X. This means when you experience yellow the retina is sending X(yellow) to the brain, etc. Now what if we had a machine that could override the retina, and send what ever pattern we wanted down the optic nerve? Would it be possible to experience colours we have never experienced before by sending new patterns outside of X? Is the colour spectrum (in)finite? Just some ideas. I would also be interested if anyone knew of any such device with which the experiment could be conducted. I don't follow how this is a philosophical issue. It is a neurology question. A more practical application would be a device that bypassed a damaged eye and provided stimulus directly to the brain. Maybe a cochlear implant is such a device as it applies to the deaf. You seem to be asking whether the brain is able to perceive phenomena that is otherwise limited by the input organ. Let's say it can. How does this change our notions of what qualia is and whether it is a distinct element of mental functioning?
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