It took me an embarrassingly long time to realize that thing with the songs and the colors was in fact what other people call synaesthesia.

There are two broad classes of synaesthetes: Projectors and associators. "Projectors" perceive the synaesthetic experience to be outside of their own head, superimposed on the literal experience that brings it up. "Associators" perceive the synaesthetic experience to be inside, visible to 'the mind's eye', but not physically applied to the literal experience of whatever is coming in from outside. An associator looks at the Wednesday heading on the calendar and "knows" that Wednesday is feminine and solemn; a projector looks at the Wednesday heading and "sees" that although the print is physically black, it is simultaneously also a bright scarlet red. Now that I know the difference, when I read pop-sci articles I can usually pick out which kind of synaesthetic experience the interviewee is talking about, but most of the people doing the interviewing do not have synaesthesia themselves, and they tend to characterize all of the experiences as if they were projected.

This matches up very poorly with what happens in my head. Almost all of my various short-circuits are associative -- all of the stuff I 'see' when I listen to music happens on an imaginary plane between the world I physically perceive with my eyes, and my brain where all the interpretation happens. It's the same imaginary plane my eidetic snapshots display on, in fact. Also where the action happens when I'm reading a book, where graphs and transformable spaces are located when I'm chewing on advanced math, and where the wireframe reference for the design lives when I'm trying to piece together a garment from scratch. Seeing what's in front of me and 'seeing' what's in 'front' of me simultaneously presents no particular problem. I can get distracted by one and forget to pay attention to the other, the same way anyone can get distracted by a particular widget on the desk in front of them and forget to pay attention to the rest of the room, but for the most part the two screens run concurrently, and have done as long as I can remember.

[I do get the it-is-black-but-also-red thing, it's just entirely internal. Anecdotally, a lot of synaesthetes report being able to envision "impossible" colors, which is either brilliant or annoying, depending on what you're trying to do with it. Imagine something like a peacock feather, or an opal, which seems to contain many different colors within its structure at various depths and angles of incidence. You can see each of those colors in turn by making arbitrarily small changes to the angle at which you view the object. Now imagine what happens as the change in angle necessary to switch between colors becomes smaller and smaller. The limit case, where δΘ→0, is an impossible color, where all of the colors present in the object are visible simultaneously without any change in viewing angle.

This drives me fucking crazy sometimes. I have been known to go on a tare looking for a specific color of pigment or fabric, or to spend hours with colored pencils trying to work out how to shade something so it matches what's in my head, only to finally realize I am picturing a color that cannot exist in real life.

One of the few cases where I was aware it was an impossible color from the get-go was in pterry's Discworld books, the wizards-only color "octarine". I just assumed that everyone could picture the counterfactual color, even though it obviously did not physically exist. It's a sort of a pumpkin orange and kelly green at the same time, if that helps anyone.]

Because my chromesthesia is associative, it's more roundabout and less distracting than it might be. I'm not hearing a song and literally hallucinating a field of color. It's more like Proust and his madeleines -- the experience of hearing that song reminds me intensely and inescapably of the experience of seeing a particular shade of blue. Sometimes it's a more complicated visual, and sometimes it's other modalities in addition to/instead of just color, but that is the general gist of it. The color, and whatever other visuals are involved, comes up on the eidetic plane. They are vibrant and very very specific, to the point where the color temperature can change slightly but noticeably if I'm using a different set of headphones, or have accidentally fucked with the equalizer settings. I finally had a brainwave and grabbed a Munsell color picker app for my phone, so that I can just show people what color I'm 'seeing', rather than waste ten minutes of circumlocution trying and failing to explain it.

My theory on what is going on is basically accidental databending. Databending, or at least one aspect of it, is when you take a file that was encoded as a particular form of data -- like an MP3 -- and open it in an application that was meant to open a different thing entirely -- like a graphics editor. Most of the time, trying to interpret an MP3 as a JPEG is going to result in a glitched mess that looks like nothing in particular, but occasionally you get something cool out of it.

Figure that memories are encoded as literal, physical patterns of firing neurons. The odds are that the actual shape of the firing pattern looks little or nothing like the thing it's encoding. If I'm staring at a rat, my brain is probably not literally playing connect-the-dots in the outline of a rodent. So there has to be some sort of lookup table. If the lookup tables are local, then patterns can duplicate between them, as long as no one pattern is used twice in the same department of the brain. Something goes into my noggin, gets routed to the auditory processing center, sets off firecrackers in Configuration #37, the auditory processing center checks the table, it goes 'oh, that's a C chord in the guitar fill', all is fine.

If Configuration #37 accidentally gets CCd to the visual cortex as well, then the visual cortex also checks its lookup table for that particular pattern. Configuration #37 might not exist on that table, in which case nothing happens and the misrouting fizzles out there. But if Configuration #37 happens to also be on the local visual table, the visual cortex finds it and shouts back 'tourmaline!', and voilà, a color comes up to go with the sound.

Sometimes collisions like that happen. The phonemic sequence [], exists independently in two of the languages I speak. In Japanese, spelled 『だめ』, it means "don't [do that]/stop it," and in Spanish, spelled « dame », it means "gimme". The two tongues are from opposite ends of the planet, and etymologically completely unrelated. (Seriously. Spanish is from the Romance branch of the Indo-European languages; Japanese is Japonic. Their most recent common ancestor is "humans invented talking".) That string just happens, by sheer coincidence, to be valid in both. Given that, I have no problems believing that Configuration #37 just happens to mean things to both the sound processing and color processing departments of my poor confused brain-meats.

The reason I assume this is going awry somewhere down on the hardware level is that it's possible for it to clash with my conscious expectations. If I happen to have two songs on my playlist with similar beginnings, and one of them comes up when I'm expecting the other, I have one of those ack, thpppbt moments you get when you sip from a glass expecting Sprite and find out it's actually seltzer. It tastes perfectly fine for seltzer water, but until the realization strikes, it's disorienting and wrong. I tend to go wait, why is that violet? shouldn't that be periwinkle? and then I figure it out.

I can ignore it fairly easily, the same way I filter out all of my random pareidolia. I just apply a sanity test to the inputs -- that came in via the ears, don't be daft, it can't be a color. For all I know, other people do this at the unconscious level. I've just moved a lot of stuff up to the conscious and semi-conscious levels of processing, because my basic sensory filter is fucking terrible, and I have enough capacity to compensate. (Mostly. The more exhausted I am, the less I'm able to discard extraneous stuff as quickly as it comes in, and the more I want to hide in a corner and cry.) I can also opt not to ignore it, which is generally how I entertain myself while waiting for trains. I assume I look like I'm staring idly off into the middle distance, usually at something visually boring, like the wall tile or the gravel trackbed.

This system of spurious accidental associations isn't confined to raw sensory data. If ever I draw one of those comparisons that makes perfect sense as soon as I explain it, but has you wondering how on Earth I managed to jump straight from point A to point B, I probably didn't. Somewhere around point A-and-a-half, the concept I was working with got misrouted and kicked back a spurious match to Q out of nowhere. Q generally has no logical relationship with A, especially if it's in the wrong sensory modality (or wrong semantic category, or wrong temporal aspect, or some other kind of wrong Fach), but this is probably not the first time it's been sent back as a false positive. If I rummage around for the list of other things (B, F, 23, 9782i, Wingdings fish) that have previously come up Q for no reason at all, those almost always have a logical connection to A, and actually now that I think about it, B makes a useful metaphor for the point I'm trying to make.

Overall, this is one of those things that by rights ought to make me barking, howling, completely non-functionally mad, but doesn't, because one of the few bits that is not generally broken in my brain is the reality testing. I use it ruthlessly, particularly when reading people, who trigger it no more or less than anything else in the universe does. I do know a lot of formal psychology, and I make conscious note of tics and microexpressions and vocabulary and all that, but in essence what I'm doing is creatively misapplying cryptographic techniques to everything. Using the spurious coincidental associations to quickly dig up "similar" behavior I've seen in the past gives me orders of magnitude more ciphertext to work with than I should rightfully have.

I usually figure out how and why they're "similar" about the same time I figure out what they're likely to mean. This is probably cheating. It definitely weirds people out. I have been generally trained by society to leave out the step with the Wingdings fish in it when I explain my reasoning, because getting the audience past that is more trouble than it's worth. I didn't realize other people didn't do that until rather late in the game, so it took me a while to learn how to verbalize it, too. I often write it out and then wind up hacking it off the start of blog entries before posting; if you're not in my head with me, it tends to come off like the cold starts on The Simpsons, where the first five minutes of the episode is a patently ridiculous situation which serves solely to set up the main plot, and then is never spoken of again.