Some people in my social circles just had their Myers-Briggs Types done, along with a consultation with an MBTI therapist... and I've been doing some self examinations (I have an MBTI coming up in the new year).
I usually think of myself as an Introvert b/c when the party is over (and I may have had a really good time at the party) I need down time, alone time and peace and quiet.
But lately I've noticed that being left alone... in the house, in the office, etc... is entirely bad news for me. I stop being happy, I stop being upbeat and even, when contacting people in that alone-state, I just get all grumpy.
I still would rather go to a party or the mall or the street and just observe - rather than interact - but I'd rather have people about. I'd rather work in a coffee shop than at home. I may not want to "Socialize" but I do need to be social.
I think that's extroversion, in the M-B model. I think. On the other hand, the fact that I prefer the inner monologue, even when at the mall, may be introversion. Not sure. What I do know is that left alone with my inner monologue doesn't seem to be very healthy. Granted: asking the question is probably a sign of introversion anyway.