On my drive today, it occurred to me that introversion might better be seen as a "condition" rather than a "characteristic." What I mean is this: We commonly say that a person "is" introverted -- as though that were a fundamental characteristic of them as a human being. But what if it is instead a condition -- the way a person behaves due to their situation?
One thing: if introversion were a characteristic, we would expect a person to always be introverted -- but in fact, many introverts become very outgoing in the right circumstances -- generally, when they find themselves in a group of like-minded people with whom they can fit in. The fact that a person can be introverted in one situation and extraverted in another implies that the situation causes the condition, rather than something inherent in the person.
So what causes introversion? My initial hypothesis is this: introversion is a combination of three factors -- feeling like one does not fit in with the people one is currently surrounded by, 2) wanting to engage in the group only if it is likely to result in acceptance and fitting in, and 3) Being either unwilling or unable to expend the mental energy necessary to fit in. Extraversion, on the other hand, is a combination of wanting to interact and either a) fitting in, b) not fitting in but either not noticing or not caring.
Thus, a person is not an introvert because there is some "introversion" characteristic in him, but because he is unable to fit into the group, and so he finds it excessively difficult to engage the group. It's possible not to fit in for two reasons -- a) you understand what is going on in a group, and find the people around you to be intolerably stupid, or b) you don't understand what's going on in the group because you are not sufficiently acquainted with the culture of the group. In other words, you can be introverted because you're in a group of people you find stupid, or because you perceive yourself to be too stupid to participate and be accepted.
Of course, place that same person in a situation in which he feels like he fits into the group and is accepted, and your "introvert" suddenly becomes an extravert.
This would also explain the common phenomenon that introverts need time to "recharge" alone, because social interactions tire them out. It's not that the social interactions themselves tire them out -- it's that, because they don't fit in, interacting takes a lot of mental energy -- like speaking a second language -- and it tires them out. But again, place that "introvert" in a group that he can connect with, and suddenly the need to "recharge" disappears.
Extraversion, of course, is either fitting in, or not fitting in and either not noticing or not caring. Thus a socially adept person would connect with a group, and become very outgoing because he felt accepted and understood. Alternatively a socially maladapted person would not realize or not care that he was not fitting in, and consequently would be very outgoing in the group, but (because he did not fit in) would ultimately drive others away.
Therefore, introversion is a combination of three things -- 1) Perceiving that a set of behaviors are acceptable or unacceptable to a group, 2) Wanting to interact only if you expect that interaction to result in acceptance, 3) finding yourself in a situation where you perceive that fitting in is either impossible or so difficult as to be exhausting.
Take away any one of those three conditions, and an introvert magically becomes an extravert.
Seems to much better describe the experience of introversion. And it explains everything in terms of "wants" and "perceptions" that can be recognized and altered by the person, rather than a native "characteristic" with which one is stuck. I like that.