One of my commenters suggested I read some of the synaesthesia research published by Richard Cytowic, so of course I immediately went and got basically everything he ever wrote -- well, the books, anyway; I haven't been through the papers -- through the Boston Public Library system. (To steal a quote from Moggie, I don't know how to like things casually.) The Central Library is under construction right now and I am a lazy bastard, so if I want specific volumes I just put a hold on them and have the librarians pull them for pickup. Wandering aimlessly through the shelves is for when I want something to read but don't know what. Boredom is a known hazard with me. The library card has joined my T pass, ID, and debit card in the phone case, as part of the minimum possible set of items I might need to keep myself out of trouble at any given moment -- I can't go anywhere without a music player, which means I can't go anywhere without the phone, which means I can't go anywhere without whatever is in the wallet case. Or, in the case of the earbuds and my keys, dangling off of it.

The first three things BPL coughed up were The Man Who Tasted Shapes, Wednesday Is Indigo Blue, and Synestheisa: A Union of The Senses, of which I have more or less finished the first two.

The first thing that has become apparent is that Cytowic is the ultimate source of all of the one-liners cited in the popular press when someone wants to write a fluff piece on the weird things brains do. The lady whose husband had a voice that brought up hot buttered toast, the cotton candy kisses, and the eponymous man who felt cool glass columns when he tasted spearmint are all from Cytowic's work or personal correspondence. I first recall hearing about all of these people well over twenty years ago in one of those Time-Life book series my parents bought. (We had the hard science one and the Forteana one. One thing I will give my parents credit for: In our house, we read the opposing arguments. We also had one on military aviation, I think, but that was more because Dad was an aeronautics engineer than because we thought we'd have to defend the homestead from an F-18 Hornet.) The same stories are told again and again, and I have to wonder why. Sean Day still runs the online Synesthesia List -- I know, because I'm on it -- and there are still calls for research participants mixed in with the art projects, so someone still has to be looking into this.

The second thing that jumps out is that the tendency of the press to speak of all synaesthetic experiences as if they are projected "outside" is also down to Cytowic. His definition of the condition makes it mandatory that the extraneous sensory ping happen "outside", which nettled me until he accidentally got to talking about the relatively high co-occurrence of synaesthesia and eidetic memory. He is using "experienced outside" to mean "not being generated in-house by the imagination," not as in, "gives the impression of being located in space exterior to the body". Some synaesthetes do get apparent projections in space (i.e., hallucinations), but he does at one point specifically state that others describe their experiences as happening on the same 'screen' that shows the eidetic snapshots, just as I do.

[Interestingly, he also draws an explicit parallel to the experience of some patients undergoing neurosurgery. There are various types of brain surgery that require the patient to be awake and responding to stimuli, so the surgeon can figure out where to cut to not leave the poor schlub with a head full of pudding. The way they do this is to pump you full of numbing agents and then poke a fine electrode into your head-meats while you are still conscious, down which they send a weensy electrical current to activate whatever happens to be at the end. The idea is that if that particular neuron runs, say, one of your favorite feet, you can tell them that's where it goes and then they won't hack away at it. All manner of weird things float to the top when you flip switches au hasard like that, and patients have reported Proustian flashbacks of all kinds of random moments of their life; they describe it as 'seeing' the memory and seeing the OR crew at the same time, without any cross-interference. This is, in fact, precisely how my eidetic memory works. And how impossible colors like octarine work, for that matter.]

Why he decided to describe it as "outside" in the first place, I don't know. My conceptual sense of where the eidetic plane lies puts it in the middle of the workflow, sitting between the raw data coming in through the retina and the post-processing done by the visual cortex. My proprioceptive sense, such as it is, puts the screen inside my head, literally between eyeball and brain. Just a big vertical transverse plane right behind my face. I think the geometry doesn't quite work IRL, but I put it very firmly in the post-capture part of the signal chain, which I would not personally consider 'outside'.

[It may be that I place the eidetic plane there because I'm annoyingly myopic. Humans are not born knowing how to visually estimate distance; they learn it, essentially by learning to keep track of what their eyes have to do to bring things into focus. Your eyes rotate toward and away from the nose, giving you an angle of convergence, and muscles squash and stretch the lens and goo of your eyeball to adjust the focus, which gives you a degree of accommodation. You learn that seeing something twenty feet away feels like 'this', so the next time your eyes are in 'this' configuration, you figure you're looking at something twenty feet off in the distance.

That's why autostereoscope widgets like a 3DS make you feel like you're looking into a shadow box. They can make things appear to float above or behind the screen by adjusting the separation between the left- and right-eye images, but the focal plane for all of the pixels is still going to be on the surface of the display. Your brain thinks they must be separated in space, because you have to keep changing the angle of convergence, but they can't be that far apart, because you're never changing focus. Ergo, Mario must be stomping Goombas in a wee little diorama.

Generally, when I check eidetic images or watch the musical light show, I stare at something boring. (It doesn't work as well when I close my eyes, for some reason. Dunno why.) I'm pretty sure I track objects in the scene as if it were a physical photograph, so I'm probably physically adjusting aim and convergence out in meatspace, but it's a pixel plane, and I don't need to adjust my focus to check the back row. Since I'm mildly short-sighted, I have to try harder to focus on things farther away; laziness brings my focal plane in closer. 'Seeing' a clear image without any ocular effort at all might just confuse the renderer and set its Z-priority at -1, i.e., clipping through my sinuses,]

Cytowic's science seems good, and when he's forced by a collaborator (or MIT Press) to write an actual academic work, his research is both fascinating and useful. Left to his own devices, on the other hand, he gets to gibbering about how he thinks synaesthesia says profound and meaningful things about human nature and evolution. The Man Who Tasted Shapes is part science and part memoir, which I generally don't mind -- I love reading Sacks and Feynman and Hofstadter and all that. But that whole book gave me the same kind of heebie-jeebies I get from people who talk about Indigo Children. One hopes he has calmed down somewhat in the intervening thirty years, but if he hasn't, he sounds like exactly the sort of person I would never, ever mention any of this to at a cocktail party, lest I get trapped in a conversation a minimum of one of us is going to regret.

Chromesthesia is a weird thing my brain does. My brain does a lot of weird things. This one happens to be a thing I find interesting, which provides me with a great deal of entertainment. The fact that it exists in some people does have implications about how human brains work in general, in the same way that watching how brains malfunction when injured helps us deduce how they function when they're not. It is not a key to unlocking the ontological mystery of humanity. It does not make me more or less evolved. It also does not per se make me more or less intelligent, more or less spiritual, or more or less connected to the world. I happen to have figured out how to do helpful things with it, but that's down to me being a tool-using hominid. Synaesthesia by itself is no more an advantage than the existence of rocks. You still have to come up with the idea of stabbing things and work out how to knap flint before you can invent spears.

On the more reasonable side, Cytowic has a bunch of theories about the mechanics of synaesthesia which are of some interest. (I'm not sure that synaesthesia is a unitary condition, which is always caused by the same root set of circumstances, anymore than epilepsy is, but never mind that.) The gist of his postulate is that the over-connectedness required for synaesthetic experiences to trigger probably exists in all humans when very (like, pre-language) young, but fall off as the brain prunes back excess connections between neurons. The phenomenon is brought to consciousness when and if the cortex for some reason fails in its normal job of inhibiting spurious signals.

I don't know if this is the case for all synaesthetics, but it's entirely plausible for me. I sit in for psych experiments at Harvard and MIT from time to time, and I have startled some of the linguists rather badly by failing to react as an ossified adult language-speaker to their trials -- the process by which I deduce meaning and pick up new constructions is what they expect to see from small children. I use the same cryptanalytic procedure for learning everything new, and my brain is overactive and staticky in general, so I have no trouble believing I have for some reason failed to fully mature out of an early hyperplasticity stage. I also have trouble downgrading the salience of anything, and have to intentionally discard a lot of observations that probably ought to have been trashed by my cortex long before they came to my conscious attention.

I've learnt to work with this, but honestly, a lot the containment strategy is just applying brute force computational power. If I were any less terrifyingly smart to start with, I'm not sure how I'd cope. Probably poorly. The more fatigued I am, the more difficult it is to sort things out. I get incredibly crabby when I'm tired, and want everyone to go away and leave me alone in a small dark hole. It's harder to ignore everything, including the synaesthetic imagery, and if I'm really dead I tend to just stand on the platform listening to music and watching the light show until my train shows up. Anecdotal evidence, and some of Cytowic's trials on a friend of his, suggest that synaesthetic experiences are suppressed by stimulants and enhanced by depressants, following the general trend of their effect on the inhibitory systems of the brain -- basically, if you keep throttling the clock speed on your cortex down, it eventually just throws a load of unorganized shit at your conscious mind and goes 'sod it, here's everything I have, you sort it out'.

[I would also add that attenuating outside stimuli also makes the synaesthetic imagery more prominent, at least for me. Cytowic doesn't seem to have done any trials with dissociatives, but I have, and the less I notice stupid shit like gravity, the more bandwidth I have for interesting weirdness. This might be idiosyncratic. I don't know the effect of DXM on cortical function, and I don't know how developing a habit of introspection might affect the semi-automatic thought processes that happen when you're on loads of drugs. Probably I'd get similar results from floating in a saltwater isolation tank.]

There is also passing mention of migraines co-occurring with synaesthesia, which Cytowic unfortunately does not follow up on, This may be relevant to me as well. One of the more simplistic theories of migraine genesis postulates that it's kicked off by a spot of cortical depression, perhaps caused by localized variation in blood flow, that transforms into an outward-spreading ripple via synaptic propagation. The idea is that the weird things migraineurs get as auras are a symptom of a sort of reverse-seizure. A seizure is what happens when something kicks off a storm of too much electrical activation in a chunk of brain, and it causes symptoms when it gets chaotic and out-of-control; conversely, in migraine, the wave of too little electrical activity that spreads outwards from the initial cortical depression leads to temporary brownouts in systems like visual processing, auditory processing, language generation, edge detection, and so forth. Your 20-minute headache warning involves things like losing proper binocular vision and big strobing blank chunks in your visual field, or at least mine does, and a lot of the visual effects I get are not unlike the primitive animations that accompany especially vivid songs.

One of the more overwrought passages in Shapes is when Cytowic gets his subject-friend into a scanner and discovers that while he's having synaesthetic experiences, the blood flow to his cortex is at a level more normally associated with people who are completely unconscious, not walking around and talking about how they needed to season the chicken until it was sufficiently 'pointy'. I'm just going to point out that I have positional orthostatic intolerance (i.e., if I stand up too fast, I get the whirlies and a stabbing pain at the back of my head), and that I have to avoid things that tank my blood pressure like niacin and alpha-/beta-blockers, because they make my head hurt like fuck and kick off migraines, and leave it at that.