I remember reading in the Eides' book (what is it called, again?) that we have different kinds of long-term memory, which all function independently, and most of us have a preference. I believe they identified visual, auditory, and motor, and perhaps something else. Anyway, I thought it was really interesting because I actually learned how to spell words by using my motor memory. When thinking about how to spell a word, I often trace the word in the air (though these days my finger barely moves). Or I think about what motions my fingers would make on the keyboard (and my fingers may or may not twitch along with my thoughts).
I wonder if the mouthing is not the same sort of thing? Using one's motor memory to memorize things not typically associated with motor function? I'd recommend the Eides' book regardless--it was truly fascinating.
