Yes, that makes a lot of sense. I wish my other teachers had taught us about this when I studied Russian and French. I am sure they all hold their mouths and jaws differently!
I actually felt like Swedish forced me to be a slightly different person than I am normally. It's hard to describe, but to really get the language right it can feel like you're exaggerating emotions whereas I like to "play it cool" in English and I have a deadpan sense of humor. In Swedish I felt like I had to be more expansive and maybe even sound a bit more confident than I am.
Another thing was that it sometimes made it easier to say things correctly if I imitated someone I spent a lot of time with, using their intonations and rhythms. But then I would be confused as to whether I was copying their Swedish or actually "borrowing" their personality a bit, which was an uncomfortable idea!
Some time ago I saw an article about how people change their personalities when they speak another language, and I thoght about that when I was writing the post. I thought that may be is a part of movin your face differently. That may be we unlock something that's hidden in our own bodies when we start movien different muscles. It was a very scientific article, so I guess you're not wrong when you talk about being a different person on your Swedish learning.
That "Borrowing personality" part is kind of scary, haha... But at the end we always tend to act pretty much like the people we spend more time with, so I guess that also might be true.. jeje
I just started following you. You should follow me too! n.n
I'm still just a minnow, but I'll be working to become a turtle or something else soon x)