The other day, when one of my friends was kindly driving me back home and I enjoying the benefits of free transportation, we were discussing the inherent weirdness of some neurologic manifestations. He was telling me about an enigmatic condition called Alice in Wonderland syndrome (AIWS). People with it experience distortions in their perception of the size of objects. In particular, these distortions can be somatic, involving one’s own body or body parts - one might feel like one of their limbs is larger (macrosomatognosia) or smaller (microsomatognosia) than it really is, reminiscent of Alice’s conservation-of-mass-violating adventures in the eponymous story. Lewis Carroll himself might or might not have drawn inspiration for the strange occurrences that happen to Alice from his own migraine auras, of which he was a known sufferer.
I’m pretty sure that many neuro fans out there (myself included) are drawn to the discipline because of the WTH-factor that comes with these kinds of manifestations. There’s actual evidence of this, in the form of “intellectual content of the specialty” being the most cited reason for choosing neurology out of other specialties and Oliver Sacks being the most cited name in neurology personal statements. In case of AIWS, it goes “how would it be possible to feel that your leg is twice as big, when you’re seeing it normal size right there? WTH!”
But…
What if the rest of us, who have not experienced AIWS before, are actually the weird ones?
The fact that organic, undirected (i.e. macroscopic) alterations in brain activity are able to take away our normal perception of the sizes of things, conversely means that there is something in the human brain, whatever it might be, responsible for holding together a reasonable perception of size, one that is good enough to let us function in our environment. Who’s to say that the default state of size perception is the “normal” perception most of us have, instead of AIWS’s micro or macrosomatognosia? Or maybe more likely - what if the default state of size perception is to have no size perception at all? The notion that there is something in our brains responsible for size perception rather than nothing means that size perception does not come for free. In other words, in our day to day lives, we take size perception for granted.
What other seemingly mundane features of our experience were paid for us by evolution, so that we could have them for free? At the tip of the iceberg are functions we might not even know we have lest we learn about them in a neuroscience course, impaired in many of Oliver Sacks’ WTH-laden narrations. These features are at the surface so self-evident, axioms of subjective experience, we rarely even think about them - they’re just a natural part of experience as a whole. The fact that they can break down, though, is an indication that they’re not simply an obvious part of experience (spoilers ahead!):
Exhibit: The Man Who Mistook His Wife for a Hat
Function: Recognizing faces
Intuition: If you think about it, faces in our visual field are nothing more than a bunch of pixels arranged in a certain spatial distribution. However, we are somehow able to instantly notice when someone’s left lip commisure is just millimeters higher than the right one, or when the distance between their eyes is millimiters high or millimeters low. Millimeters in inanimate objects are usually worth cents; in the human face they’re worth thousands of dollars, as the plastic surgeons can surely attest to. This extremely uneven distribution of importance by any other non-human standard would definitely be baffling. Incidentally, evolution did not buy you dog face recognition - would you be able to tell 20 dogs apart from each other just by a glimpse of their faces?
Exhibit: The Man Who Fell Out of Bed
Function: Recognizing one’s own limbs
Intuition: That hand in front of you, it’s obviously yours, right? But how obvious is obvious? Visually, it’s connected to your trunk - but then again, it’s nothing more than a bunch of pixels separated from everything else by a color border. You feel from your hand when it touches something, but you don’t seem to think twice about its ownership when it goes numb status-post compressing it on the armchair after passing out on a Saturday night. You can move it whenever you want, except when you can’t in the previous scenario. There has to be something else that makes the ownership of your hand so obvious, some axiom deep inside your brain saying “that hand is mine.”
Exhibit: The President’s Speech
Function: Picking up the emotional quality of speech
Intuition: It’s automatic for most of us to detect emotion in speech, as if emotion were a fundamental property of all human utterance. But the actual fundamental properties of human utterance are just the fundamental properties of sound waves, like amplitude, wavelength, and change over time. Before arriving at emotion, we first have to identify speech from all other sounds using a really complex function of these three. Features specific of speech, like tone and pacing, are intuitive midpoints that are also encoded from these fundamental properties, now in the context of speech. Only after that is emotion probably encoded as another really complex function of midpoints like speech tone and pacing. Emotion in speech is not that obvious from this perspective: a complex function over another complex function.
It’s relatively simple to break down the axiom that faces have distinguishing characteristics - recall how a basic digital camera can’t recognize faces because it sees pixel-by-pixel or how hard it is to train a computer algorithm to even be able to tell a face from a beach ball. It’s also simple to break down the axiom that speech has emotional undertones - recall how a digital microphone picks up only modulations in the amplitude of sound waves and the ongoing efforts to make computers decode speech sentiment. Suddenly these features of experience are not so obvious anymore. Step one was identifying obvious axioms of our conscious experience; step two was trying to understand why they weren’t so obvious after all - that we were actually taking them for granted.
If we go deeper searching for axioms of experience, we find the most obvious bunch of them all - that we can see, that we can feel, that we can taste, that we can hear, that we can smell, that we can think. Here is where things start getting strange. Here, in the bottom half of the Iceberg, below the surface of the water, lie not the senses that hide in textbooks, but those found even in nursery rhymes.
Take for example, the experience of touch. Sit in a chair and close your eyes. You might notice the sensations of your arm reclining on the armrest, your back against the back of the chair, even the temperature of the air on your face. You might recognize yourself noticing these sensations, arriving at simple, yet powerful realizations: “ah, this is how sitting feels like,” or “ah, this is how the armrest feels like.” With practice, you might get good at identifying, moment by moment, how different things feel like.
But why does the armrest against your arm feel like this? The axiom kicks in, “because that’s how the armrest feels like.” The unsatisfactoriness of this automatic response emerges: you realize you’re taking touch for granted. What, exactly, does the armrest feel like? It feels solid, and you can feel it under your arms. What makes up the sensation of “solidity”? You know you can tell when an object is hard or soft, but what exactly makes up that sensation is something you are unable to put into words. What does it mean to feel it under your arms? You can tell from touch where an object is with respect to you, but when you try to explain the sensation of whereness you arrive at the very same dead end. You feel it - but what is that feeling made of?
Going through this thought process and asking what sensations are made of takes at least several minutes of curious exploration every time. This is where I think meditation can be helpful. It’s also not a trivial task to genuinely question our senses - I find vision to be the most difficult, probably because it’s the one most “obviously” tied to day-to-day experience. However, I do believe there is true insight to be obtained down this path. Perhaps in the end, all sense experience equally ineffable, nothing really particular exists about any single modality. Perhaps all of it is made up of the same substance, that which all experience is made of, which we might call in simpler terms being alive. If being alive is what we ultimately take for granted, there’s a lot of work left for us to do.