Qualia, Experience and Memory.

I want to invite resolutions/speculations on the following thought-experiment:

Unknown to John Doe when he wakes up one fine morning, his brain has been suitably and precisely altered, such that the range of ‘yellow’ colours have been replaced with an alien hue, hereby designated Alhue. In other words, whenever John looks at what previously was a shade of yellow, he sees the corresponding shade of Alhue. The new hue has been incorporated into his perceptual spectrum, such that there is no discontinuity or incongruity. So, he can’t look at a shade in between orange & yellow and notice something obviously amiss. The new hue blends in suitably.

Will John Doe realize that his yellows have been replaced?

“John doesn’t know it yet, but we’ve replaced his regular vision of the color yellow with Folgers’ Crystals[sup]TM[/sup]. Let’s see if he notices…”

Have John’s memories of yellow things also been tinted in Alhue? If so… it’s the same as if nothing happened. When his his cones are stimulated at a certain frequency, he sees a color which he calls yellow and remembers as yellow.

How can you be certain that you don’t see what I would describe as Alhue when you see yellow? How would I describe it? If I point to something that’s yellow, you see what you perceive as yellow.

That’s the $64,000 question, isn’t it?

As I understand it, recall/memory is like software/data. You don’t literally store pictures, you store information. So, if I recall an old yellow book, I reconstruct the scene based on the associations and context that I encoded. So, I should see the scene in my minds’ eye as an old Alhue book, thinking of the colour Alhue as being labelled yellow. If this is so, how do I know my colors don’t get replaced every night or, say, gradually? Well, they certainly seem to remain the same.

The inverted spectrum is a common argument. Philosophers of Mind often propose dilemmas of this nature, expending every effort to tease a notional “what it feels like” element away from the physical.

I’m afraid I find it improbable that they ever will particularly convincingly. Yellow is E-M radiation of wavelength between ~565 and 590 nm. Alhue must also have a characteristic wavelength, even if it is off the visible scale: 300 nm (“ultra violet”), for example. There are various means by which a person can ‘rank’ their perception of a given colour, such as colour space or by simply composing a matching colour on a computer application.

So, what happens when John is shown an object reflecting 570 nm light, ie. something “yellow” and asked to place it on a colour space or match it in Microsoft Paint? If all the aliens did was effectively write a bit of “brain code” such that
IF 565nm<incoming_wavelength<590nm THEN incoming_wavelength=300 nm;
(ie. all yellows become, say, ultra-violet) he would simply point to the yellow region of the colour space and compose a yellow Paint colour, both of which his brain-code was continually “mixing down” to UV rather like a Beat Frequency Oscillator in an electric radio. However (assuming John can now see actual UV just as easily as “mixed-down yellow” UV) the researchers would presumably find out pretty quickly that John could see invisible things such as the security markings on their equipment or the patterns on certain flowers only usually visible to bees (who can see in UV) - there is clearly something other than simply “what it feels like” that has changed here, and measurably.

So, the experiential part of the experiment appears no more paradoxical than building a radio. But, as others have asked, what of John’s memory here? His memory comprises stored images formed when 570 nm was not “mixed down”. Quite apart from the apparent impossibility of altering a memory formed with a given wavelength so that it is remembered with a replacement wavelength, is there any noticeable difference between what John remembers and what he sees today? Again it would seem that, whatever the characteristic wavelength of Alhue was, he would likely remark on the fact that he can “see in” that wavelength now but cannot remember being able to do so before.

All of these paradoxes, from “Mary in the black & white room” to “what it’s like to be a bat” to the “Chinese room” appear to take some essential feature of explaining qualia and either discard it completely or alter it in some impossible manner before presenting us with a “Ha! Try explaining qualia now, smarty pants.” I believe (but cannot falsifiably demonstrate yet - that it the challenge of 21st Century neurophysics) that all qualia can be explained with reference to physical sensory input, received by some physical apparatus, “encrypting” different levels of physical memory which are subsequently “reactivated” (ie. recalled). The OP’s paradox appears to founder on the simple impossibility of ‘swapping’ a specific element in an entire memory while leaving the rest the same.

So, more generally, I do not find the inverted spectrum plausible without some drastic physical change accompanying it. In this respect I’m with Daniel Dennet.

Well, if you assume beforehand that the percept of ‘yellow’ is objectively determined by the wavelength, then there’s not much to argue here. What if the percept is a response to the wavelength? Where Alhue is invoked by ~565 - 590 nm, in place of yellow? Do I take it then that a difference or something amiss won’t be noticed, according to you?

You see, this is where these qualia arguments become mired in rhetorical quicksand. The moment I introduce a physical entity common to all qualia of yellow, my opponent objects that that’s not what they’re talking about. All I can do is mirror the question: “What if ~565 - 590 nm was the source of the qualia, and you could call it yellow, Alhue or whatever you like?”

Yes, I am positing that if no physical change is made to the wavelength of the light as it is captured and processed by the brain’s apparatus then no difference in the qualia is possible. If both Alhue and yellow are the qualia induced by ~565 - 590 nm, they are identical and equivalent qualia. To me, hypothesising an inverted spectrum without any physical change to the wavelength of incoming E-M radiation is like hypothesising telekinesis.

Generally speaking, what I know of science suggests that there are two ways to alter color perception. One is to change the photosensitive chemicals in the eye to accept or target different wavelengths, which would be SentientMeat’s suggestion. The other is to change the cells’ behaviors in response to the breakdown of these photosensitive chemicals which I took for the OP’s suggestion (changing things later than the rods and cones).

The limit of objective investigation ends in subjective reporting of events. Even if all parties, after a specific change, report that what was once yellow is now blue (say, a familiar color-object like a banana), we are still not sure that they all see what the experimenter would see when he sees blue (his quale), or that they even agree with each other independent of the experimenter. Qualia are simply unavailable for anything other than strictly subjective perception. Strangely, also, there is no guarantee that your memory is not perfectly fallible WRT these qualia because there is no reliable method of testing or demonstration. Even if a subject reported, “I see a new color,” this is completely unverifiable (or, if you are so inclined, unfalsifiable).

The question that I think is most interesting is whether quale exist at all, in the sense that they are completely unavailable for any public/inter-subjective evaluation. What can be said about them at all? Nothing obtains, there is nothing other than solipsistic certainty (which isn’t certainty at all) that they are stable, and they are unavailable for inspection by anyone other than the subject.

do you make the assumption that the percept is independent of the physical object being perceived?

if so, what is the causal mechanism involved? is it dualistic?

if not, what makes you think the percept can be changed without the physical object changing?

if a change is noticed, it would be impossible to determine whether one’s memory was altered, or one’s perception was altered. also, do you think the memory of the perception is altered, or do you think there is only the perception of the memory?

Not completely independent. There might be a longer chain of dependence, say, instead of photon -> perception, it could be photon -> interpretation -> perception.

so do we perceive the photon, or do we perceive the interpretation? and what is the interpretation, and how does it receive the photon as input?

I’m just explicitly positing an intermediate link in order to logically allow qualia to have some degree of freedom with respect to the initial input. As far as what the interpretation is, the same as what it is currently believed to be. After all, except for Penrose et al, consciousness is held to be a classical phenomenon. Hence, there is some finite time lag between input, processing and conscious perception. Of course, it is more accurate to say that most hold the processing itself to be conscious activity. There’s still a time lag. Insert the “interpretation” within that space.