I'm almost certain that I'm an introvert. I base this conclusion on the way I process information. I have never been able to just "run with" a new concept, including the concept of introversion. It takes me forever to really "get" something, to feel it in my bones. If I had known that growing up, I would have given myself more time to do so, instead of trying to rush through everything at everyone else's pace. For example, as a musician, I had to really internalize someone else's song before I got comfortable playing it. I had to know what it was about, how the tune came to them, etc. Sometimes I wouldn't like a new song until years after the first time I heard it.
My working hypothesis regarding my social anxiety, based on the preponderance of evidence, is that it stems from my failure and the failure of those around me to accept my introversion. For example, there are those people who expect introverts to be seen and not heard. If you state an opinion, express a preference, write something coherent, or otherwise stand up for yourself, they'll act shocked -- first of all, that you were capable of sustained thought, and second of all, that you had the affrontery to do so in their presence. I have actually been accused of plagiarism by people who thought I was incapable of writing complete sentences. That pisses me off. When I treat myself the way people like that treat me, I piss myself off. This has a lot of adverse health effects, and it has to stop.
I can't do anything about how other people see me, but I can change how I see myself. I believe it's incumbent upon me to achieve self-awareness, self-acceptance, etc. Part of self-acceptance is figuring out what introversion means to me. How do I express it? Will I be a hermit? I don't think that works any better than trying to be the life of the party. If I'm completely alone for too long, even with my cat to keep me company, I get wiggy. If I'm forced to interact with too many people for too long in a way I don't like, I am totally fried. I think I feel most comfortable being around at least a few people, without feeling compelled to interact with them in some way that doesn't feel natural to me.
I also tend to avert my eyes and fidget a lot. It's also nice to know that the
latest research shows people who do this aren't necessarily perverts.