Feedback, and paying attention t it.
Your face does a lot of stuff.By "stuff" I mean a thousand of sensor inputs-per-bogglesecond. That's a lot.
Each of these sensors produce data, all-the-time. Your brain receives these data. And you ignore them, even lots and lots of them. Did anyone ever even teach you to pay attention to this? No, probably not; what use have kids for this information when-they-are-kids.
In creating an expression, many muscles fire. But not *just* fire; fire in a particular way; speed, volume, inclination, force, area, base-wave, and so on; and the individual sensors are packed like terapixels all over your body, all firing atthesametime. Too many data for an ESP32 to handle; or any computer; but your brain effortlessly processes this and streams it to wherever its required.
If this "expression" was in view of other humans, or potentially so; a whole other slew of circuits are in play, but for now we focus on the internal feedback mechanisms at work.
Last week, when you did that grimace, or something very like it; it felt like a wave against a beach, but today it feels like a wave against a stony beach, mapped down to micrometres. You will ignore this, even when it feels like the North Sea crashing against cliffs you will still ignore it.
Not me. I'm pulling all sorts of mad faces in response1. I didn't expect to be the first human to discover this. I thought it so obvious as to not need mentioning. But look around. People look decades older than they actually are, and they haven't abused their body nearly as much as me. Of that I am certain.
Listening to your body, is a thing. But that's not listening, is it? That's like saying you've got "five" senses. Useful in song writing, but far-removed from reality. Your ears are no help here, but I get what they are saying. They're just not saying it enough.
You have ONE-TWO-THREE-FOUR-FIVE-SIX-SEVEN--- and so on, SENSES WORKING OVERTIME. These fuckers are all over your body and using your nerves, can let you know about all sorts of things it would take good doctor and some harmful scans to otherwise discover; if they could; and if they catch it in time; by which I mean disease; cancer, and so on.
Your sensor network keeps on working, even when you, Da Masta, are doing something else entirely. Normally they are So Quiet2 you don't "hear" them.
But when they shout, it's definitely worth a listen.
;o)
references:
1. One girlfriend informed me are "facial exercises". Oh really.
2. Hah! Bjork now!
2. Hah! Bjork now!