I bought a plastic mat to put underneath my desk chair, to protect the wooden floor from having bits of stone ground into it by the chair wheels. But it kept sliding when I stepped onto it, nearly sending me stumbling into my large, expensive, and fragile monitor. I decided to replace the mat as soon as I found a better one.
Before I found a better one, though, I realized I wasn't sliding on it anymore. My footsteps had adjusted themselves to it.
This struck me as odd. I couldn't be sensing the new surface when stepping onto it and adjusting my step to it, because once I've set my foot down on it, it's too late; I've already leaned toward the foot in a way that would make it physically impossible to reduce my angular momentum, and the slipping seems instantaneous on contact. Nor was I consciously aware of the mat anymore. It's thin, transparent, and easy to overlook.
I could think of two possibilities: Either my brain had learned to walk differently in a small, precise area in front of my desk, or I noticed the mat subconsciously and adjusted my steps subconsciously. The latter possibility freaked me out a little, because it seems like the kind of thing my brain should tell me about. Adjusting my steps subconsciously I expect; noticing a new object or environment, I expect to be told about.
A few weeks later, the mat had gradually moved a foot or two out of position, so I moved it back. The next time I came back to my desk, hours later, having forgotten all about the mat, I immediately slipped on it.
So it seems my brain was not noticing the mat, but remembering its precise location. (It's possible this is instead some physical mechanism that makes the mat stick better to the floor over time, but I can't think how that would work.)
Have any of you had similar experiences?
You can think "turn left" and without any other conscious input your body executes a successful left turn on the bicycle. Something is happening in between; the common name for this something is 'muscle memory'. It's not necessarily a great name.
We don't know exactly how muscle memory works, but we can make observations about its functioning. For instance, that it cannot consist solely of exact repetition of motions, and that it must be able incorporate real-time sensory feedback (or else biking would be impossible).
Do we disagree on anything?
Only the usefulness of the name. "Stuff" would more clearly capture what we know about it. :) I think we can leave it there.