In light of the article that referenced business school advocating extroverts, I’d like to direct you to this article from the New York Times. It talks about confidence, and that fact that the human experience is so very… well, varied, that there are no clear parallels.
(I give the author huge props for not imposing his own perspective on the study’s results, and simply acknowledging that there’s not a one-size-fits-all answer. Hurrah to complexity, to gray areas, to waiting until a conclusion can be drawn before drawing a conclusion. What a breath of fresh air!)