I'm immediately reminded of Terry Pratchett's "octarine" (referenced frequently in the Discworld books) and David Lindsay's "jale" and "ulfire" (in A Voyage to Arcturus). I'm sure other spec fic authors have made reference to colors that human beings can't usually perceive, either because they don't exist on earth (dubious) or because we're not equipped to see them (more plausible). Makes me wonder whether some synesthetes see ultraviolet, or infrared, or sound waves, when they look at numbers or letters or shapes.

Because I’m a physicalist ... it refutes the premise of the Mary’s Room argument

I'm completely unfamiliar with all of this as a formal study. Reading Mary's Room, though, the first thing that came up was something my akido instructor said.

"You can 'know about' something. And then you can 'know' something."

He was using it in reference to the Aikido textbook that went with the class. You can read it all you want, but if you can't actually do it, can't practice it, can't actually experience it, then there's something that you don't know.

I read the "Mary's Room" thought experiment as saying you can learn everythign you want to learn about Aikido, but you can't actually practice it on another human being. Once Aikido-Mary meets an Aikido instructor in a dojo, can she learn anythign?

And I'd say absolutely.

There is nothing you can do that will prepare you to hold a helicoper in a hover but to practice it until you can do it, until you experience it. And now that I can do it, there is nothing I can do that will have you hold a hover on your first attempt. I can guide you and offer tips and whatnot, but you've got to do it. Statistically, you'll have to spend at least a few hours flying helicopters before you can do it reliably and consistently.

If "Mary's Room" is basically asking whether we can know everything there is to know about something without experiencing the thing itself, my experience says 'no'.

A discussion i used to have with friends back in high school when we were feeling philosophical: "What color is your orange?"

By this we mean that, two people looking at an orange both agree that it is orange. Those two people also look at a traffic cone and a safety vest and agree that they are orange. The color wave length that reaches both sets of eyes is named orange. But does orange look the same to both people? Maybe what you see as orange looks like my purple. And what you see as purple looks like my turquoise. The wavelengths of light are given agreed upon names, but maybe the subjective experience of what that looks like are different.

We loved this conversation, because there was no way to prove or disprove it. It went well after ingesting large qualities of sugar and caffiene after a late pep band rehearsal.

R.A. Lafferty wrote a short story on the subject. The protagonist creates a device that lets his see through the eyes of another. A very telling bit is that he has a crank experience the world as something imperfect and disgusting; the protagonist realizes that living in such a world would make anyone cranky.

Of course, the center of the story is the disgust the protagonist experiences when he sees the world through the eyes of a woman he's attracted to.

I love Lafferty's writing. He doesn't bother with reasonable premises— he starts from sheer absurdity and goes from there.

Kayjayoh @ 3: It gets interesting when you find someone who demonstrably has slightly different color perceptions than you do. My partner Andy and I can agree pretty well on the colors of clothing, books, painted walls, and such--things dyed or colored by humans. But we disagree in consistent ways about certain things in the natural world, especially flowers. There are flowers I see as blue that he sees as purple.

More interestingly, there are flowers I see as entirely white that he sees as white with purple patterns. We're moderately confident, because of this, of a hypothesis that he sees slightly further into the ultraviolet than most humans.

(There are also a few things that I see as blue that are gray to him; there's a narrow range of blue that he doesn't see as colored at all.)

So it's not just that I can't ever know that the sensation I describe as "blue" is the same one that Andy or Jo describes as "blue"--it's that I know that even if we had the same subjective sensation, it wouldn't be stimulated by all the same selections of wavelengths.

I have full (normal) color vision and my husband has a mild form of color blindness. He can see red in bright light, but there is no question in my mind that what he experiences when he says or sees red is *not* what I experience. For me, part of the "red" experience is that the color leaps out; for him, it does not. Is that the sort of thing you mean by "qualia"?

Some time ago, I read that one reason so many kids say blue is their favorite color is that children see more shades of blue than adults-- you see it more strongly, or something along those lines. I would much like to expand my visual spectrum somewhat. People are used to differences in hearing, but not so much this part of sight.

Rose @1: I'm sure other spec fic authors have made reference to colors that human beings can't usually perceive, either because they don't exist on earth (dubious) or because we're not equipped to see them (more plausible).

IIRC there were a bunch of those in the early 20th century, though not always given discrete names-- Lovecraft, of course; possibly also Edgar Rice Burroughs and Robert Chambers-- I suppose because the infrared and ultraviolet parts of the spectrum must've been brought to general public awareness.

Good Omens has "ultra-black" in a marginal note somewhere. WRT "octarine", I regret to report that there are people who have adopted the term in all apparent seriousness to discuss new evolving chakras or auras or something.

There was some vague stuff in the news a year or three ago about people with visual pigments that *can* see a slight way into the ultraviolet spectrum; I can't recall whether the explanation had to do with tetrachromats-- people with fourn visual pigments instead of three, mostly women who are heterozygous for red/green color-blindness.

As we've been discussing, how we see the world in color differently from others isn't an issue most of the time. In high school, I had one friend who I knew was color-blind, but it was a fact that didn't seem to affect anything. Except for one day when we sat down to play Uno. I think he agreed to play because normal Uno was fine for him - the bright colors distinguished themselves enough that he could make out differences between them. But we were playing Extreme Uno, which has different cards. The colors are set against a black checked background, making it extremely difficult to him to see which color was which. Unfortunately, he didn't inform us of this until more than halfway through the game. I think our universal thought was, "No wonder he was losing!"

It was a moment I still remember because it reminded me at how differently we perceive the world and how easy it is to forget that.

Kayjayoh, #3: Interestingly, the first thing I thought on reading that article was that it looked like a definitive answer to the "Is your red the same as my red?" question.

B. Durbin, #4: Do you happen to recall the title of that short story?

Remember, for those of us with color blindness we can see more colors than we normally do by wearing one red contact and keeping both eyes open. (The approximately two working color pigments we use + red-shifted images from the two working pigments--2+2=4. I'm told it makes working out resistor bands a snap.) For those that aren't color-blind who do the same they should see 3 + 3=6. What would the difference be? Beats me--I've never heard of someone with normal color vision desperate enough to have a red contact lens ground for one eye just to check.

Greg (in #2), I think you're misunderstanding the intent of Mary's Room. It's not a parable about book learning versus practical experience, it's a thought experiment asserting that there's an irreducibly non-physical aspect to mental experiences.

Of course, the real problem with Mary's Room is that its premise assumes something that's obviously impossible, and it then goes on to assert that the "obvious" conclusion is a description of the real world.

Greg (in #2), I think you're misunderstanding the intent of Mary's Room. It's not a parable about book learning versus practical experience, it's a thought experiment asserting that there's an irreducibly non-physical aspect to mental experiences.

Of course, the real problem with Mary's Room is that its premise assumes something that's obviously impossible, and it then goes on to assert that the "obvious" conclusion is a description of the real world.

People who have had lenses removed for cataract surgery can see further into the ultraviolet, though I don't know whether the replacement lenses undo that.

That color perception isn't objective has been known for some time. I remember reading Edwin Land's research on the subject in Sci. Am. some decades back.

B. Durbin @ #4: Thank you. I read that story in a collection in middle school, and have been trying to think of the title and author ever since.

Mary's Room seems (to me) to prove that there are aspects of physical existence that can't be understood without direction perception. But I suppose that's a less exciting conclusion.

Remember, for those of us with color blindness we can see more colors than we normally do by wearing one red contact and keeping both eyes open. (The approximately two working color pigments we use + red-shifted images from the two working pigments--2+2=4. I'm told it makes working out resistor bands a snap.) For those that aren't color-blind who do the same they should see 3 + 3=6. What would the difference be? Beats me--I've never heard of someone with normal color vision desperate enough to have a red contact lens ground for one eye just to check.

Avram,
I was going to say something similar in response to Greg @2 - but you beat me to it :) Yes, Frank Jackson in the Mary thought experiment was attempting to prove that physicalism isn't true, but positing that no amount of third-person data will lead to first-person knowledge of something.

One of the problems, as someone else has pointed out, is the usual thought experiment problem - you're asked to take on an absurd premise (in this case, that someone can know all there is to know about colour vision) and then try to draw some sort of common-sense conclusion from a story using that premise.

Searle's Chinese Room comes across the same problem, and indeed the sensible solution is the same one given for the Chinese Room - it's effectively the "Systems Response" to Searle. In terms of the Chinese Room, Searle is tricking us into a category error by pointing to the person in the room as the Chinese-unknower ("But look! He can respond to Chinese questions, but he still doesn't understand Chinese! QED"). The analogous entity to the human brain is the room itself (the whole system); it's the book plus communications slot, with the neural activity carried out at a snail's pace by the bloke in the room.

Mary, with her comprehensive knowledge of human colour perception, is like the bloke in the Chinese Room after he's memorised the entire book. Maybe she's a bit further ahead than him - all he has is a whole lot of incomprehensible synapse gates or something. But even so, what Mary needs to do in order to model colour perception at an experiential level is to instantiate that knowledge as a kind of mental subroutine. The knowledge has to become part of what Mary is.
Whether that's "possible" or not is a practical question, and no more absurd as a premise than asking that Mary memorise all that stuff in the first place. If she could do it, then she could indeed translate a whole lot of data into "knowing how it feels".

Searle's man in the Chinese room is actually slowly ticking over the mental activities of a completely different person - that's another trick that Searle performs, in distracting us from the fact that different people will respond differently to questions in Chinese. So what's being modeled is a complete person, not just some kind of idealised "comprehension-of-Chinese".
Mary is similarly supposed to be able to ingest "apprehension-of-colour" to the extent that when she sees a red rose she just goes "Yup, a red rose, that's what I thought it'd feel like to see one".

There's certainly something absurd going on in these thought experiments, but it's not due to the assumption of physicalism!

And by the way, thanks for the actual post, Avram! It's absolutely fascinating, and does indeed lead to some really interesting kinks in Jackson's Mary-style thought experiments, but it's anything but a win for the dualists/qualiaphiles.

("someone else" = Avram. Sorry!)

Vicki @5: There are flowers I see as blue that he sees as purple.

Gosh. Nearly the same thing happens with me and my husband, except with more things than just flowers-- but there's a consistent color range which I see as (or at least call) "blue" while he insists they're "purple". OTOH, this could easily be a difference in mental categorization rather than biological function-- there was that interesting survey/discussion here in ML a while back about the difference between "gray" and "grey".

And then there's the Berlin/Kay theory of the development of basic color terminology in various languages, which is nifty but not without its detractors.

Rose Fox, #1: "I'm sure other spec fic authors have made reference to colors that human beings can't usually perceive, either because they don't exist on earth (dubious) or because we're not equipped to see them (more plausible)."

Yes. Hugh Lofting, Dr. Dolittle in the Moon (1928), in which Dr. Dolittle voyages to the moon and discovers new colors entirely outside the red-blue-yellow spectrum familiar to our eyes. (Or red-blue-green, if you want to get all conical about it.) I must have been all of five or six years old when I read this, but the pure adrenal charge of sense-of-wonder it delivered to my brain remains with me in memory to this very day.

(I'm absurdly pleased to discover via a Google search that Richard Dawkins, of all people, remembers this bit of Dr. Dolittle, and discusses it in the Barcodes in the Stars section of his book Unweaving the Rainbow: Science, Delusion and the Appetite for Wonder.)

I found out I was red-green colour-blind at age 10, and it was at once a huge blow (because it meant I couldn't be a pilot or an astronaut), and a revelation, because it explained why I saw things differently from how other people saw things. Like the vividly red grass over there, for example. Or people with green hair. See a lot of green, actually, often in places where people swear there's actually a kind of light brown. And don't get me started about blue and purple. My wife and I run into this a lot. "Ooh, check out the fabulous purple on that car!" "Sweetie, that's blue." "I think you'll find it's purple." "Blue." etc.

Once I tried a German language class. Thought it might be interesting. It was the kind of language class where the teacher only speaks in the language concerned. And one of the early lessons was identifying coloured pencils, quickly, within a time limit, in German. Guess whose brain exploded?

The other problem I've had with colour perception all my life is when people find out I see things differently (usually after I ask someone to pass me that green thing, and they go, "What green thing? Oh, you mean this brown thing?") there immediately follows all the questions, "What colour is X?" where X is every mundane object under the sun, including the sky!

The "how do you know this is red?" question is a curly one I've often had to deal with. I see a lot of red. Sometimes correctly. When asked the question, I have to refer back to situations where someone has indicated that a given object is red (regardless of what it might look like), and this new phenomenon matches the way that previous example looked.

My wife and I play a lot of videogames, too. Frequently these feature a lot of tricky details using red or green as toggled options of some kind. At such moments I have to hand it all over to Michelle to sort out because I have no idea which is which. Doesn't help when the "green" thing often looks like a shade of grey (the green of traffic lights, for example, looks grey).

I also need various assistance playing games like snooker, as well, to distinguish all the differently coloured balls, many of which look either identical, or at least so similar as to be a problem.

Avram,

I, too, am a physicalist, mostly because none of the arguments I've seen for dualism are either testable or really intelligible in terms of the world we all live in*. Most of them involve some bizarre thought experiment that actually turns out to be a shellgame or some other sort of intellectual sleight of hand. The various species of zombie and zimbo are such cons**.

Mary's room fails as a useful test case because it's a rigid categorization of the possible outcomes of Mary's entry into a technicolor world into either "getting new knowledge" or "not getting new knowledge". But suppose she learns nothing new, but has a new experience, one she never had before, which gives her new sensations, but not new knowledge? Sensations are not qualia, so they're allowed to be based entirely on physical processes; they can be neural states. But what room does that leave for qualia? What additional phenomena do they explain? None I'm aware of.

Peter Hollo

Thanks for bringing up Searle; I was going to if no one else did. In Searle's case I think it's pretty obvious that he doesn't want to believe in physicalism, and is grasping at whatever straw he can find to deny it. I take from his arguments that he finds the notion of a non-physical consciousness somehow ennobling, and the idea that the human mind and consciousness†† are physical is just degrading to human dignity. Do I need to point out that this is a religious argument, and not in any sense either a scientific or philosophical one?

* Unless you live in a different one. I've been leaning towards the belief that a lot of philosophers come from somewhere else.
** "Imagine a world just like ours, except that no one has conciousness.† Now doesn't that prove that consciousness must be non-physical?" Nope, just proves I can believe six impossible things before breakfast. Waffles, anyone?
† I've never heard anyone remark on that particular puzzle that only people who already believe in souls would even entertain such a question.
†† There are philosophers, and I can't remember if Searle is one of them, who hold that the mind and consciousness are disjoint, so that even if the mind is based on physical processes, the consciousness, which is some sort of ineffable "other", is not. Sorry, guys, I can eff that easily. There's nothing that the concept of a non-physical consciousness adds to the concept of "mind" that would explain anything else, or predict phenomena we can't otherwise explain with fewer mental contortions.

C. E. Wingate,

Oddly enough, one of my eyes has always been sensitive just a little deeper into the ultraviolet than the other, so I've always had evidence that physical color perception was not limited to a single mapping of colors. I first noticed this as a child, so it has nothing to do with the fact that I have had one of my corneas replaced because of cataracts. In theory, the replacement could allow me to see a little farther into the UV because it's plastic, but in fact the difference is very small, if any.

And I don't believe that Land's experiments prove that color vision "isn't objective"*, but just that it isn't the straightforward implementation of trichromatic processing that everyone had thought based on 19th century experiments**.

* Unless you mean something very different from what I think you mean by that.
** There was an article in Sci Am in the 1960s that described those experiments (by Maxwell, IIRC), and pointed out that they didn't prove what was thought because none of the filters and photographic emulsions had the spectral sensitivities that the experimenter thought they had.

Fascinating issue.

I'm going to go out on a limb here and ask: Is sex a "qualia" or not?

I think now that before puberty, I didn't understand what sex "was". It was more like a science-fiction concept.

Imagine an alternate version of the "Mary's Room" experiment... where Mary is raised up to adult age in some ultra-Victorian environment where sex is explained in the most clinical way possible, but sensuality is never so much as suggested. Will the actual experience of sex teach Mary something new?

(This probably sounds familiar to anyone who's seen George Lucas' film THX 1138, but a film can't be used as a scientific argument.)
:-S

I'll admit I'm not sure what, precisely, the Mary's Room scenario is supposed to be testing. The Wikipedia article Avram links to does say this:

It is important to note that in Jackson's article, physicalism refers to the epistemological doctrine that all knowledge is knowledge of physical facts, and not the metaphysical doctrine that all things are physical things.

What that seems to suggest is that "physicalism" posits an extremely limited definition of "knowledge" as something akin to "book learning." And, indeed, the quotation from Jackson's original article -- Mary as "a brilliant scientist forced ... to investigate the world from a black and white room via a black and white television monitor" -- seems to support this. (But a quick look at the Wikipedia article for physicalism suggests that "physicalism" may mean something different and more complicated, so I'm reluctant to go too far with this.)

Knowledge exists on various different, overlapping levels. There's the abstract, "knowledge of facts" level ("The capital of Nevada is Carson City"; "Color processing in the brain leads to this particular set of neurons being active"); the pre-dictionary[*] knowledge of the meaning of words in your native language; the memory of a particular pain; the sound of a familiar voice; the knowledge of how to run a maze; the habitual "muscular" knowledge of how to throw a ball; etc.

It's perfectly possible to suppose that all these different sorts of knowledge are physically instantiated/encoded in the brain, while being accessed and processed on different levels. Thus, as Greg points out, knowing via book learning all the details of how to fly a helicopter is not the same as learned physical training in flying one; the two sorts of knowledge are probably encoded, stored, and accessed in different forms (and in different parts of the brain).

(I suspect I'm largely agreeing with Bruce Cohen @22, except that I'm happy to include "sensation" in the category of "knowledge.")

[*] In the sense that people knew how to use words in their native language long before lexicographers came on the scene.

re 21: Back when our offices were in Silver Spring, my window looked out onto the railroad tracks. (I once helped the police catch a bad guy on the tracks from my lofty aerie.) One day another fellow was in the room with me and I pointed out to him the private car on the end of the Capitol Limited.

Him: "You mean the brown one?"

Me: "You're red-green colorblind, aren't you?"

It was Pullman Green, a very deep olive color.

Surely the only way for Mary to have full knowledge of the color red is to experience it, because her mind (that knows all about the physics of color and how the eye perceives it and how the brain processes it, and so on) is not a mind existing somewhere all by itself, but a mind that inhabits a brain that has intimate neurological connections with sensory organs. When Mary first sees red, things happen in her body: receptors in her eyes see red, and transmit new red signals to her brain, and her brain gets a new experience, that of seeing red. Without Mary having that bodily sensation which connects to her brain and her mind, she can't fully know how red is subjectively experienced.

The same goes for hovering a helicopter, or riding a bicycle, or sex. They are all physical activities which cannot be fully understood until your body has done it and your brain and mind have taken in the sensations involved in using and controlling parts of your body which it had never used or controlled in exactly that way before. Those sensations cannot be communicated by book learning because they are different inputs into the brain. And they are not simply new sensations, but new knowledge because the sensations that have been transmitted to the brain have given learning and understanding to the mind.

Rose Fox @ 1: "I'm sure other spec fic authors have made reference to colors that human beings can't usually perceive, either because they don't exist on earth (dubious) or because we're not equipped to see them (more plausible)."

Gene Wolfe's fugilin, the shade that is blacker than black. There's another that's whiter than white, but I forget what it's called.

Mary's Room:

From the description I just read on Wikipedia, I'm certainly a physicalist. Yet I have no problem at all granting that Mary learns something new when she walks out the door. That the experience of seeing red is qualitatively different than the experience of studying it doesn't seem to me to prove anything at all about qualia.

A child, opening its eyes and seeing a red object for the first time knows what the color red is, even before they know the word for it. This does not teach them anything about how their eyes accomplish this feat of perception. If the experience of red has no relation with knowledge of the neurophysiology of color perception, then why assume the inverse?

Heresiarch@#28, far be it from me to dispute Wolfe with someone with your nym, but I think it's `fuligin'. (It's also a word whose source is quite obvious, for Wolfe: a backformation from `fuliginous', which is a perfectly good Latinate English word attested from at least 1621 (according to a quick web search, others will have better resources for this sort of thing than I).

Rose Fox @ 1: I think I remember that in one of Enid Blyton's books (The Mountain Of Adventure, I think) the children reach the secret base and discover that the villainous scientists are making something of a colour that they've never seen before. I can't remember what the thing was, but I think it was liquid, a big pool of it, and in my mind's eye I see it as turquoise.

It's practically the only thing I remember about that book, because I found the idea so startling. But I'm not sure if she even thought she was writing SF. Perhaps she thought scientists could actually create brand new colours. As an 8-year-old reader, I believed that.

And now I really REALLY wish there was a way to cure colour-blindness, even if only temporarily. Because I want to know whether the above-mentioned colour-blind synesthete is really "seeing" the colours he normally misses from the spectrum that other people perceive. In which case, is the range of possible colours hard-wired into the brain, even without being experienced? Which would seem odd, given that it doesn't seem as though blind-from-birth people are able to adequately envision colour. Or is it that, once certain colours HAVE been experienced (those in this guy's visual spectrum), the fuller range of colours can be deduced?

Or is this something else all together- is he "seeing" colours which, for most people, don't even exist? Is it only this staid practice of using our eyes for seeing that is preventing us from accessing the much wider spectrum with which our brain is able to cope?

All very interesting, leaving aside Mary's Room. (Which I agree seems flawed as a thought-experiment.)

Lemon Lime Gatorade:

Green or Yellow?

You'll find that females generally identify it as yellow, and males as green.

I'm told it has to do with the ratio of rods and cones being different for men and women.

I'm not sure how it fits in, but hey, it feels like it should be relevant. Aproposness? Relevantiness?

hm. Well, perhaps reading about Mary's Room in an attempt to understand physicalism isn't the best way. So I went and looked up physicalism in wikipedia. It didn't help.

It seems to be saying that there is no difference between "mind" and "brain", or that anything "mind" can be explained solely as "brain". or something.

Either I'm not understanding the point, or it's parsing as absurdity. I'm certain my experience of emotions could be mapped into a collection of synaptic firings (given another millenium of technical advances or so), but that doesn't explain anything about my experience of whatever emotion I'm feeling.

It seems to boil down to the "mind/body" problem, and personally, I never understood what the big fuss was about whether it's mind/body, or whether it's all mind, or whether it's all body. To borrow from Luther, each individual has their own personal relationship with mind. And I don't need some pope, or some physicist, or some philosopher, telling me how I should relate to God or how I should relate to my mind.

Am I missing something?

Can someone explain physicalism in such a way that it doesn't sound like a turf war with the religious types over the ownership of my mind?

I'm red-green colorblind, so every time I've used red or green in a story I've made references to colors I've never seen.

I don't get the argument against qualia at all. Psychologists have proven that some colors evoke certain emotions, and these emotions are subjective. Even assuming you could predict these responses down to the firing of every synapse, that's a long way from actually experiencing it yourself.

My dad's red-green colorblind, and he says that he can distinguish the colors, but that the difference doesn't leap out at him. I am forced to accept this as truthful, since he has absolutely no reason to lie to me about it, but it makes no sense to me--how can it be hard to tell the difference between red and green if you can tell the difference at all? I can picture just not being able to distinguish; in my imagination red and green both come out as a sort of muddy color...

When I was little Dad used to take me clothes shopping to ensure he got the color he wanted. Once we walked out of a shop on the verge of paying for something when the salesman who'd been helping us went into the back room for something and I said, "Dad, I thought you wanted a brown suit." The salesman had been told brown, but had gone through all the fitting with a grey suit which he was about to sell. The most charitable explanation is that he was colorblind too, but if so he shouldn't have been working in clothing sales.

Meanwhile, Liam has the same shifted-into-UV thing that Vicki's partner has. Somewhere around blue-green our perceptions start diverging. However he seems to be able to see a little further into IR as well, which suggests he just has a broader range of visible light than I do. And we have a nomenclature disagreement about a particular shade, which is a very red orange to me and which he insists on referring to as "process red" even while admitting that it's orange. He says process red is the correct technical name; I say that the technical name and the name to be used when talking to one's partner who's never done any printing are two different things. :)

Bruce@16: you don't need an expensive red contact lens, any more than Von Daniken(?)'s cavemen would have needed access to an x-ray source to illustrate skeletons. Red cellophane or a piece of red lighting gel should do the trick.

(I'm not sure that doing this would add to the colour experience of people who were already trichromats, though)

"...wrote about the color-bland [sic] synesthete"

Is that someone who smells everything in shades of beige?

I have mild synaesthesia (mainly for numbers), but what interests me more is emotional responses to color. Some of this may be due to compatibility -- I have blue-greenish eyes, so I like blue-green shades, and now that my hair is graying I also like paler sage green -- but it can *feel* like it goes deeper.

My computer allows a color scheme set up, and I've got it in tones of "not as crude as turquoise" shading into something more tawny at the top bar, with utilitarian tan for the tool bar, and it pleases me greatly. I recently bought some coasters in similar shades (with varying prints) at Cost Plus, and I still feel delight every time I look at them. Is this a "woman" thing, or do some of the guys here have it too?

Greg London@33,

As I see it, the war between physicalism and dualism is rooted in religion, but it goes further than a turf war over mind ownership. If your mind is entirely made of atoms (so the theory goes), then there's nothing to salvage and send to heaven when you die. Therefore there must be an immaterial component of your consciousness that is preserved after the rest of your body decays.

And then there's the subject of free will vs. determinism, which I enjoy as a dilettante but am thoroughly unqualified to discuss.

A lot of how we think of colors, I think, is probably based on the language we're using...Japanese people say the traffic light is "blue" when it's not red or yellow. Nowadays many people certainly will say "Well, it's green, but we call it blue" but it seems that in the past, blue and green were sort of mixed, or perhaps the dividing line between green and blue was different from where it is to Europeans. I certainly think it's possible for there to be more or fewer divisions between colors than we usually make, the number seems pretty arbitrary, especially considering how "purple" and "violet" overlap to most people.

I remember reading that some people...criticized? were disappointed in? Helen Keller's writing because she talked about sights and sounds, and they wanted to learn what it was like to live without them. But I think she said something like her whole consciousness was based on books she'd read, and every book, of course, describes sights and sounds. Her world wasn't made of physical sensations, it was made of words. (But I don't want to put words into Helen Keller's mouth, I may be misremembering completely.)

#40: Lots of languages don't have separate "basic color terms" for blue and green. This does not mean that people who speak one of those languages don't understand the difference; it just means that they have to say something longer if the difference matters. "grue, like new grass" versus "grue, like deep still water" for instance. (Yes, the word "grue" is used in the literature on this topic, and I still haven't gotten to the point where I don't think of Zork.)

There is a huge body of semi-controversial research on which languages have which basic color terms and why. I can't really do better than point you to Paul Kay's website: http://www.icsi.berkeley.edu/~kay/

Part of the problem I see in the Mary's Room situation is that it begs, very painfully, of wnat exactly is "knowledge" in the first place. I'm leaning extremely heavily on the "akido" theory.

Something that is bugging me here: If we succeed in making a totally computational (that is, AI-based) model of a particular human mind, doesn't that in fact give us a kind of dualism? If one can describe and model human thought without going to the trouble of modelling the biology of neurons, then it implies that if we say that the two minds (biological and computational) are the same (in the sense of one being an accurate copy of the other), the mind exists in some way other than the mere physicality of how it is represented.

Also, allow me to throw another thought experiment into the mix. Suppose one were to intercept the visual processing of a synesthete and feed it into the same stage of a normal person's visual processing. Will they see the non-existent colors? How about if we hook up our colorblind synesthete instead? It seems reasonable to anticipate that the normally sighted person would identify at least some of the "martian colors" as normal colors. If we reverse it, the color-blind synesthete might be able to give some of his "martian colors" names if his visual paths were stimulated with signals from normal eyes.

Lots of languages don't have separate "basic color terms" for blue and green.

So, do you guys know about the color term progression? The theory basically says that there's an order in which languages add color terms. It's not quite as absolute as the original theorist made it out to be, but it goes like this:

If a language has only two color terms, they'll be "white/light" and "black/dark". If it has three, the third one will be Red. If it has four, the fourth is either Green or Yellow, and five adds the other of Green or Yellow. Then Blue, then Brown, then Pink, Purple, Orange and Grey in any order until it has all 11.

There are languages that break this rule in one way or another (Russian has "light blue" and "dark blue", Hungarian has two terms for Red, e.g.), but it's a handy rule of thumb for conlangers. :)

I think your AI-based model would be "RoboMary" as proposed by Daniel Dennett (see the Wikipedia article on qualia, linked by Avram above) to try to get round the Mary's Room argument.

If you could make an AI-based model that was functionally equivalent to a human brain, then it would exist in the same way as this blog exists, as an entity that has individuality, yet is dependent on a physical host, and is copiable (clonable) from one host to another. If you erase the physical host (body, server) without making a copy, then it's dead.

Here's Dennett's RoboMary paper.

There's a German camouflage color from WWII called dunkelgelb, "dark yellow." Americans invariably describe it as "tan," Englishmen as "grey" and Frenchmen call it "green." Germans insist that it's dark yellow, dammit, a whole separate color. A lot of camo colors are confusing this way, but I don't know of any others that are so, well, CULTURAL.

I have maintained for years that indigo is not a real color. Show me something that is indigo and not dark blue. It's not in any of the rainbows my window prisms make (which is not a great criterion; more than one of them filters out green, but that leaves a space) and it doesn't make *sense* in the spectrum. Roy G Biv and I must disagree.

re 46: I'ts a bit more complicated than that. If you go prowling around websites you will find that non-military use of "dunkelgelb" means a very saturated, dark yellow-- what Grumbacher's sells in a tube as "Cadmium Yellow Deep". The WW II military usage is quite a mess; they seemed to have picked a color name out of the air. There are at least two different colors apparently intended by it. One is RAL 7028, which as the number shows is definitely well into the grey range. The other one is referred to as "Dunkelgel nach Muster" and appears to be pretty variable. It seems to be ochre-based, but like American/British khaki it often slides into a greenish cast. So it's definitely possible that a large component of the identification of it as different is because people are looking at differently colored objects.

Carrie S. @35: Do you not have trouble distinguishing, say, a deep navy blue from black? Or light peach from light pink? I'd think that there's-a-difference-but-it's-hard-to-tell experience might be similar to those, which I had thought were common experiences.

Or maybe my color vision isn't as perfect as I had thought!

Faren @38, wrt teals/turquoises: I recently bought some coasters in similar shades (with varying prints) at Cost Plus, and I still feel delight every time I look at them.

There's a certain range of blue-violets and violet-blues that somehow instinctively connects with something in me that produces a primal sense of "OoooOOOOOooooo". So yeah, it's not just you.

I'm tangentially reminded of the standard acceptable palette of men's clothing-- oh sure, there are nonce fashions for avocado green or pumpkin oranges etc., but almost all of the "classic" businesswear that can be worn for decades is in a limited range of navy blue, some pale blues, hunter green, burgundy, a lot of greys and browns, and black. I've heard rationalizations for these that vary from the seniority of those colors as natural wool dyes to the ethnocentric promulgation of colors which WASPs look good in; beats me.

individualfrog @40: Japanese people say the traffic light is "blue" when it's not red or yellow. Nowadays many people certainly will say "Well, it's green, but we call it blue" but it seems that in the past, blue and green were sort of mixed, or perhaps the dividing line between green and blue was different from where it is to Europeans.

That's to do with the aforementioned "grue" mixed green/blue category, which is really what the Berlin/Kay model's first invocation of "green" should be-- in Japanese (and Chinese), the old "grue" word is 青 ; when the new category 緑 split off as "green", it mainly left behind "blue" by process of elimination, but there's still some ambiguity. (IIRC there's a vaguely similar situation in Celtic languages about the color words gorm and glas, allowing for some inevitable spelling variations.)

If you go to this Chinese dictionary site (among other nifty features, it includes etymological info for many of the written characters) and enter "green" as an English search term, the latter character appears first, with sample phrases involving reasonably greenish stuff like peas, trees, and tea, but the former one still also indicates greenish stuff such as leaf vegetables and frogs, as well as the sky.

I was going to mention Japanese noun ao, but I've been beaten to it. I'll note, however, that aoi, the adjective form, can also mean "pale".

I'll also mention that many birds have four types of cone in their retinae, being able to see into the ultraviolet, though it's not known how many separate colours they can perceive.

C. Wingate @48: You're right, there's no separate indigo in a spectrum. It's my understanding that Sir Isaac Newton made it up because that made seven colors, not six, and seven was a more appropriately mystical number for his taste.

...sorry for the double post.

Do you not have trouble distinguishing, say, a deep navy blue from black? Or light peach from light pink? I'd think that there's-a-difference-but-it's-hard-to-tell experience might be similar to those, which I had thought were common experiences.

Well, sure, but I have a hard time imagining how red and green can be sufficiently close together to be hard to distinguish in that fashion, if they can be distinguished at all. This is because I am not colorblind, and it's surely a failure of my imagination. I'd think it was that the muddy color has a hint of red or a hint of green to it, but from Dad's description the colors are perfectly clear; he just can't tell them apart well.

C Wingate #42: Suppose one were to intercept the visual processing of a synesthete and feed it into the same stage of a normal person's visual processing. Will they see the non-existent colors?

I think you'd have to intercept something other than the visual processing of the synesthete (I keep wanting to write that "synaesthete," but maybe that's just me), because the colors the synesthete perceived happen as a result not of looking at colors, but of perceiving some other-than-color thing. (Colors as a byproduct of numbers, for example. Like tastes as the result of sounds, or why certain telephone rings taste like pickles. Yeah, I've got that one.) What you'd want to intercept is whatever strange neural firing in the synesthete's visual processing area(s) is happening, and route that to the non-synesthete's visual processing. (If you did it with the taste thing, and used my telephone ring experience, you'd just give somebody the taste of pickles, though, which they might well already have, at least if they'd had that kind of pickle already.)

Drat. Wait, no, I think I misunderstood what you said. Maybe that's what you meant: taking the synesthesia-generated stuff (if it in fact manifests as visual processing in the brain of the synesthete, and not in some other way) and giving it to the non-synesthete, while remembering that it is (for the synesthete) the product of something other than looking at colors.

Oh, bother. I keep getting Centipede's Dilemma with all this. But still....

How about if we hook up our colorblind synesthete instead? It seems reasonable to anticipate that the normally sighted person would identify at least some of the "martian colors" as normal colors. If we reverse it, the color-blind synesthete might be able to give some of his "martian colors" names if his visual paths were stimulated with signals from normal eyes.

Is it the eyes of your synesthete that are not normal? Or the visual processing (presumably in the brain)? Or something else? Also, synesthesia doesn't color inside the lines. if you stimulate my visual paths with signals from normal eyes, you'll probably get temperature/density/pressure sensations, which is not quite what you're aiming for. Then again, my synesthesia (if that's what it is) doesn't seem to map real well onto descriptions of it that I've seen. (It's darned useful in my work, though.)

Fascinating topic here. And I really want a sample of dunkelgelb some day.

P.S. Just now I think qualia, if they exist, don't exist in things; they exist in moments of juxtaposition. Relationship has a qualia, and that's why experience has a flavor.

P.P.S. Diatryma, I can show you the difference between indigo and dark blue right away. Indigo is the one that hums.

Carrie S. @53: I see what you mean. :) I've always thought it must be like seeing via a CRT monitor with one of the colors gone. A dying metaphor, that.

And: 52 for me should have been @Diatryma in comment 47.

I'll just go back to playing by myself in the corner, now.

I have full fledged snyaesthesia of the letters/numbers are in colour version. And not only for the Latin letters we use, but it works for Greek, Russian, Runes and Hebrew as well, which helps me a lot with languages. But the colours, and the aura of words shaped by the colours represented, are of so subtle shades that it's not easy to find words to describe some of them. What I hate is the question, 'what does my name look like to you.' ;)

Maybe some Martian words would help. :)

mjfgates, #46: My partner used to work for Volkswagen, and he says they used that color on cars up until the early 70s. The comparisons he offers to describe the color are "just a little lighter than the outside of an overdone hard-boiled egg yolk," or (more succinctly) "baby-shit yellow".

Heresiarch #28: I'm pretty sure that fuligin isn't a new color, but just evidence tha the people of Severian's culture separate what we call black into more then one color, possibly because they live in a more dimly-lit world than we do. Fuligin is used for things that are absolutely black, reflecting no detectible light at all, while black would presumably still be used for ordinarily black object that reflect enough light to have discernible surface contours.

Greg London #33 -- Can someone explain physicalism in such a way that it doesn't sound like a turf war with the religious types over the ownership of my mind? That may be like asking someone to explain the Cold War so that it doesn't sound like a turf war between the USA and the USSR.

Diatryma #47, you're right about indigo. Newton added it to the spectrum to get seven color for numerological reasons.

Lee @ 57

Ah, close to the color my father referred to as 'muckledy-dun'. (Our VW was that sort of pale brownish-pearl they used in the early sixties - call it VW off-white.)

One notes from Wikipedia that there are a variety of different types of color blindness. In the most common sort, acto them, the green receptor is still functioning but is shifted strongly towards the red. If you transplanted one of these eyeballs into someone with normal vision, then presumably they would see red objects shift towards yellow and blue-green objects get darker and shift towards blue.

I'm perfectly willing to believe that Newton arbitrarily labelled part of the normal spectrum as "indigo". But like Elise, I also have my own private indigo (as it were)-- a certain blue-violet range that goes *ping!*. Cobalt glass is toward the blue edge of "indigo"; iolite and tanzanite are also in the zone.

Perhaps within red/green color-blindness, the separation of red and green requires a similar process as a normal person trying to determine whether a nominally neutral color (e.g. brown or grey) is "warm" or "cool" wrt red/yellow or blue/green undertones?

We had one of those, too.

did anyone else have trouble parsing this portion of avram's post?

"it refutes the premise of the Mary’s Room argument, by establishing the only way for Mary to have full knowledge of the color red is subjectively experienced would be for her to also have full knowledge of how that experience is physically generated by neural activity"

maybe "...of the color red *as* subjectively experienced"?

or "that the color red is subjectively experienced"?

some other typo? or is it perfectly grammatical, and my parser is missing an obvious construal?

#54 et preq.: I know a bunch about this because someone in my lab is doing research on how it works.

Color-number synaesthesia is thought to arise in a brain region pretty deep in the visual processing graph, the fusiform gyrus. (Most well known for recognizing faces and other shapes.) The best guess is that there is more crosswiring between there and the color areas than is usual. I don't think swapping such high-level brain areas between individuals (assuming an appropriate magic wand) would do anything interesting. The details of interconnection are a function of experience, not genes, and are wildly different between individuals. It seems to me that in both swappees, they would be so badly miswired as to be useless.

Some hallucinogens are reported to produce synaesthetic effects in "normal" perceivers -- this is presumably because they crank up the sensitivity on the crosswiring that does exist in those people. (You have to have at least some, for understanding objects with typical colors.)

I have a very bad memory for faces, so maybe the synapses are too busy with that letter/colour thing. :(

On the topic of colour-blindness, one experience with my father (who is red-green colour-blind) really made things clear to me. He came home one day with a new suit. It was a very tweedy brown plaid fabric, with a hot pink thread running through the pattern. We all expressed great surprise at his selection and it became clear that he hadn't noticed the pink thread (but was able to distinguish it once it was pointed out to him) in the same way that you might imagine not noticing a forest-green thread against a variegated brown background. The red (or pink in this case) just didn't pop out.

Part of me wishes I had some degree of synaesthesia. Sadly, no. I have interpreted some things... idiosyncratically, I guess; Dad never believed me when I said I could hear mice moving when I held them, and even I was never sure if I was making it up. Even a bit of UV or IR, or a broader spectrum of hearing or any other sense, would be interesting. I know it'd also be a pain and one more thing to deal with (I can't imagine what my childhood pickiness would be like were I a supertaster) but whenever I read about something like this, I feel like the world is a blog, and some of the posts are password-protected so I can see that they're there, but not read them. Information is available, but I cannot have it.

I've seen red plastic sheets being sold for quilters, so they can tell if two fabrics are in the same range of values (light/dark). At least, that's my (possibly incorrect) understanding of the theory behind it.

Interesting site I found while looking for some stuff on color vision: a extensive discussion on color vision as it pertains to painting (in this case, water colors). Curious factoid along the way: the modern notion of primary colors seems to be a recovery of ancient philosophical notions. In between, primary colors were those that unmixed paints came in.

I actually see colors slightly differently from my left eye vs. my right eye. (And no, my eyes aren't two different colors.) Unlike Bruce, however, I have no special UV-vision.

My husband is one of those partially-red/green-blind types. To him, the flowers and the leaves of flame azalea look the same color, unless he gets very close to them in strong light. (Also, avocado green and the color of Thousand Island dressing appear the same to him.)

re 45: I haven't read the whole thing yet but there's a huge gaping hole in the first case given (the blue banana). Knowing how your brain is supposed to react to color isn't the same as knowing how it is reacting now. Indeed, in terms of perception, that perception itself is the latter knowledge. Therefore Tricked Mary cannot tell that she is having an inappropriate reaction to the yellowness of the banana on her own, without something else (in her case, a mechanism for analyzing the reflected light from the blue banana, or alternately a device for analyzing what's going on in her brain in the terms of her existing understanding) to tell her what color the banana is. Without such a device or some other color standard to compare the banana to, I would suggest that she would see a "yellow" banana, but misunderstand "yellow" to signify what really should be labeled "blue". So she would learn what blue is, but tag that knowledge with the wrong name.

C. Wingate @ 71: By hypothesis, she knows every reaction that will occur in her brain as a result of seeing the color blue, and this includes her conscious reaction. Therefore, she can differentiate between seeing yellow and seeing blue without an external device, since they cause different conscious reactions.

Then there is the possibility of human tetrachromats.

re 72: Two objections:

First, knowing what her conscious reaction would be is outside of Jackson's original version of the case.

Second, such knowledge simply begs the question. Of what would such knowledge consist? For real-world humans, knowledge of sensations consists of memories of those sensations. For example, the experience of touching wall current isn't natural to humans, yet is quite characteristic. Description of the sensation, or of how it comes about, is inferior to the experience itself. If a form of knowledge is to be postulated which consists of neither memory nor description, I for one am going to insist on a description of said knowledge that gives me some confidence that it even could exist.

As it stands, Jackson's original version with Dennett's modification is, I think, quite susceptible to my objection. The experience of analyzing something is not the same as experience of that thing. But I also object to Dennett's disquisition on how the scope of "understanding everything" is underestimated. Overestimation is also a problem, because one can easily posit enough understanding to require extra modes of thought and perception, thus requiring Mary to be superhuman. A superhuman Mary is not a suitable model for human perception; the understanding that Mary has must be kept within the bounds of what humans in general are able to understand for the thought experiment to have any validity.

#73: Damn mutants! I bet they use that fourth color to send secret messages to each other plotting the downfall of us inferior normals.

First, knowing what her conscious reaction would be is outside of Jackson's original version of the case.

"She discovers, for example, just which wavelength combinations from the sky stimulate the retina, and exactly how this produces via the central nervous system the contraction of the vocal chords and expulsion of air from the lungs that results in the uttering of the sentence ‘The sky is blue’."

I would say that if you have this knowledge, you know how to associate the stimulus with a given response. In other words, Mary could lay a "trap" for the stimulus of blue light, causing it to trigger an association. At least, I don't see how we can assume that she can't do this.

A superhuman Mary is not a suitable model for human perception; the understanding that Mary has must be kept within the bounds of what humans in general are able to understand for the thought experiment to have any validity.

I don't think it has any validity anyway. To be an argument against physicalism, Mary has to be in exactly the same physical state before and after she sees a color for the first time; but to claim that, in that state, she couldn't recognize the color is simply to assume the consequent.

It's certainly true that a real human won't learn what red looks like without having seen it, but I don't see how that has any consequences for physicalism.

I work under the theory that the Japanese had a combined term for blue/green for a while because of the ocean. But it's only a theory.

For those people who were wondering about the Lafferty story, sorry it took me so long to answer. It's "Through Other Eyes" and I have it in the collection Nine Hundred Grandmothers, ISBN 0-441-58051-3 (undoubtedly out of print; this edition is from 1982.) It's actually the only Lafferty I have, though I do keep my eyes open in the used book stores.

I am definitely not synasthetic. But I had a friend who was and insisted that different notes had different colors, which is a pretty cool trait for a musician.

Incidentally, there's a shirt I own that I refer to as green while my husband insists that it's blue. It's not too far off the color of denim, actually, so I see his point, but it's just teal enough to make me think of it as green.

Lee @ 57 - my parent's first VW microbus, Clarissa, was that greeny-yellow color. By the end of its existence, it was also liberally spattered with stick-on plastic flower cut-outs, mostly covering rust spots. I learned to drive in that underpowered, hell-in-a-crosswind, stick shift vehicle.

I recall a memory of reading somewhere that the lens of the eye tends to colour with age and exposure to ultraviolet; yellow, I think. So the colours one sees in age aren't the same colours, quite, that one saw in youth.

I also recall reading elsewhere that this is supposed to be why some languages concatenate colours: in countries blessed with strong sunshine, older people are supposed to lose the ability to discriminate between blue and green. I can't say I'm convinced, but I thought I'd throw it out here.

Kid bitzer #63, it should have (and now does) read "full knowledge of how the color red is subjectively experienced".

Winchell Chung, #73, I know a tetrachromat. She has twin daughters (fraternal) and one of them is also a tetrachromat.

Me@previously: Can someone explain physicalism in such a way that it doesn't sound like a turf war with the religious types over the
ownership of my mind?

avram@58: That may be like asking someone to explain the Cold War so that it doesn't sound like a turf war between the USA and the USSR.

I so don't get this. If a physicalist says that the "mind" doesn't exist, then why is he fighting a turf war over it?

Doesn't this boil down almost in exact parallel to the misconstrued notion that there is one question and the answer is either "God" or "Science"? Because I'm fairly certain that it's more accurate to say that "god" and "science" ask different questions.

Nix @ 29: "Heresiarch@#28, far be it from me to dispute Wolfe with someone with your nym, but I think it's `fuligin'."

How dare you disrepsect and quetsion my authotiry? This bevahior will not be torelated!

(I'm sure you're right; I wasn't totally sure and almost googled it but then I got lazy.)

There was a story a couple years back about a new fabric the military invented that absorbed something like 99% of all visible light. The picture of it looked like someone had photoshopped a square of black out of the middle. My first thought was, fuligin: check. On course to Urth; arrival in approximately a gazillion years.

Avram @ 58: "I'm pretty sure that fuligin isn't a new color, but just evidence tha the people of Severian's culture separate what we call black into more then one color, possibly because they live in a more dimly-lit world than we do."

Hm. That's an interesting theory. Where does that leave the whiter-than-white color?

NelC @ 79

From personal experience, the lens of the eye does in fact get cloudy and discolors with age. You're right, it yellows, and so the colors shift, and get a little desaturated too. This is why everyone I know of, including myself, who has had one lens replaced because of cataracts, immediately starts pestering the surgeon to replace the other. It's like having the age of your eye rolled back to when you were in your twenties. In my case, the doctor said he could probably justify the second surgery to the medical insurance company after about six months, which means shortly after the beginning of the year. I'm anticipating it gleefully.

My father is red-green color blind, but he likes to see me wearing red very much, just as he likes to see me wearing green. To his eyes, they both suit my complexion (very anglo-saxon; the architypical definition of a white person) more than shades of brown (which he mostly can see), and I and others agree.

He loves both of the popular red roses named "Mr. Lincoln" and "Chrystler Imperial", although he declares that he sees the deep red of their blooms and the deep greens of their foliage (exact opposites on the color wheel as I see them) as the same color. He is emphatic in his declarations that he sees neither red nor green as shades of grey -- he simply says that he sees opposites on what I see of the color wheel as the same shade.

Interestingly, while according to Mendelian genetics (although not according to more recent understandings), my uncle (my father's brother), who is also color blind, has a different degree of disability. I have listened to many discussions in which my father and uncle have conversed about such-and-such a traffic intersection where the shades of green, yellow, and red created difficulties for my uncle to discern driving clues (he uses position alone to determine when to go/slow down/stop -- a dangerous practice at particularly complex intersections and an even greater problem in rural areas where only red and green lights are given at intersections), whereas my father sees a different range of shades and has an easier time seeing the distinction between orange-yellows and reds, and therefore also has an easier time seeing the difference between orange-yellows and green.

As the only daughter between them, I am glad that my childlessness means that the trait (both according to Mendel and to modern understandings of genetics I am unquestionably a carrier) will die with me. My father has deeply regretted his visual handicap, as it not only limited his view of the world but has also prevented him from a number of professions he might have enjoyed (my maternal uncle, the chemist, relies on his color vision professionally; my father cannot distinguish even between blood and pus and is legally prohibited from flying a plane, to name just a few of the problems he faces; although he would never begin to compare his difficulties to other genetic diseases, color-blindness has deeply shaped his vision for his life).

The odd thing, given this genetic background, is that I consider myself to have an unusually heightened sense of color. I am a devoted crafter, so the ability to distinguish different shades and values is important to my appreciation of appropriate color combinations when I sew/knit/crochet/quilt/photograph/.... I did not inherit this ability from my mother; although I admire her color sense, she has no ability to make a match between thread and fabric unless she directly compares the two. I call my ability "color memory" because I am able to make such matches (for example, choosing between about 600 different values, tones, and shades among the several brands at my local store) for a piece of fabric I bought years ago.

I have often wondered if the X-chromosome I inherited from my father somehow gave me this ability, but I suppose I will never know if his color memory would have been equally powerful, had his Y-chromosome not defeated him, or if some other miscellaneous genetic bit gave me the advantage over my relatives. I suspect that this question is as unanswerable as whether or not the red/green my father sees matches either color as I remember it.

Bruce @84: I was wondering if one actually notices any difference as one gets older, since the visual system ought to compensate as it does under differing light conditions, but a lack of saturation does sound likely. It might explain the occasional wistful remark one hears that the sky isn't the same blue as when one was young.

Now, here's an odd thing I've noticed. In the HSB colour system, the colours of the spectrum are arranged in a wheel, with the primary colours red, green and blue at 0°, 120°, and 240° respectively. The secondary colours yellow, cyan and magenta are at 60°, 180°, and 300°. I make (less than) a living as a designer, and whenever I have to choose a blue for something, I find myself gravitating towards 210°, midway between blue and cyan according to HSB, since that looks to me more like the platonic ideal of blue than the fully saturated blue at 240°; that position on the wheel looks a little purple to me. I'm not sure what's going on; possibly the RGB colourspace of CRT and LCD monitors don't quite match the colourspace of my visual system, or perhaps my lenses are yellowing.

Oh, and fuligin? Phase conjugate mirrors. These have the interesting property of reflecting light directly back to its source, which means that under most conditions an object coated in the material should appear the colour of one's pupil, i.e. deepest black. Since this would appear to be a useful defence against lasers — not just reflecting the beam away but back at the weapon itself — I could see PCM cloaks knocking around in Severian's world, a utilitarian artifact become fashion statement become tradition.

Greg @82: A physicalist would not say that the mind does not exist. You sound like a physicalist yourself when you say @33: I'm certain my experience of emotions could be mapped into a collection of synaptic firings. If you believe your mind is a result of the physical properties and functions of your brain, you are some sort of physicalist.

It's the non-physicalist position which is harder for me to grasp. My mind is something else? What else is there?

In Searle's case I think it's pretty obvious that he doesn't want to believe in physicalism, and is grasping at whatever straw he can find to deny it. I take from his arguments that he finds the notion of a non-physical consciousness somehow ennobling, and the idea that the human mind and consciousness†† are physical is just degrading to human dignity. Do I need to point out that this is a religious argument, and not in any sense either a scientific or philosophical one?

If I recall correctly, Searle claimed it was the other way around: he was the true physicalist and strong-AI advocates were dualists, because they thought mind was the instantiation of an algorithm, independent of its physical substrate, whereas Searle insisted it was something that could only be done by a meat brain made of a particular kind of matter. But I never got what he thought these special "causal powers of the brain" consisted of.

...As for whiter-than-white, most white fabrics you see already are whiter-than-white to some extent, because they've got fluorescent pigments in them that convert ultraviolet light to visible. You'll discover this if you enter a room lit by ultraviolet "black light" while wearing a white T-shirt or white socks.

I've seen red plastic sheets being sold for quilters, so they can tell if two fabrics are in the same range of values (light/dark). At least, that's my (possibly incorrect) understanding of the theory behind it.

Another trick for that sort of thing is to put the fabrics on a copier. That way all the hue and intensity gets stripped out and you can just compare values. Very handy for planning Fair Isles patterns, where the values are the most important things.

LLA @ #85, the first link in # 73 suggests that colorblind boys have tetrachromat mothers.

Niall@87: You sound like a physicalist yourself when you say @33: I'm certain my experience of emotions could be mapped into a collection of synaptic firings.

Except "mapping into" doesn't mean the same as "completely describe". It's like taking a t