When in thought, or reading, or concentrating, I stick my lower lip out so that it covers my upper lip. In fact, I pull the upper lip into my mouth, inside the lower jaw. It seems strange, but I don’t know if it is. Is there a name for it?
It’s involuntary, and I’ve done it all my life. My mother commented that one of my nephews does the same thing.
In thought or focus of whatever kind my face more freezes into the last position. For really intense consideration I tend to freeze basically my entire body.
The one I’m more familiar with (as in, have read others having too) is slightly sticking your tongue out. I could see sticking out the lower lip being similar.
I furrow my brow. Forehead slips southward. Looks like a relief map of Turkmenistan. When I’m done, I often have to manually un-furrow. Sometimes it’s painful. My wife thinks it’s odd.