I propose to add a third kind of "vert" to the two standard categories - introverts and extraverts.
That's the "adapted introvert," who masquerades as an extravert at times, and then "re-verts" to introversion when the situation no longer demands it. I know, because I am one, and many of my colleagues in my occupation show the same pattern.
In a thirty-year career as a management consultant, seminar presenter, and conference speaker, I'm often mistaken for an extravert. People ask, "How can you stand up in front of 5,000 people and give an impassioned speech about leadership, and not be an extravert?" The answer is: it's not easy.
Most of the star "motivational" speakers, so far as I've been able to determine, are high-energy extaverts. However, many of the topic experts - people who speak about the future, business strategy, leadership, economics, technology, and organizational performance, seem to be driven by their inner achievement needs, not their needs to connect with other people. They have to get themselves "up" for intensive interactions with others, and when the mission is done they retreat to the comfort of their private interior worlds.
By the way, the Swiss psychologist Carl Jung, who pointed out the two patterns, used the term "extraversion," not "extroversion," although both "versions" are commonly used today.
Karl Albrecht is a management consultant and author of more than 20 books on professional achievement, organizational performance, and business strategy. He studies cognitive styles and the development of advanced thinking skills. He is the author of many books including Social Intelligence: The New Science of Success, Practical Intelligence: the Art and Science of Common Sense, and Mindex Thinking Style Profile. The Mensa society honored him with its lifetime achievement award, for significant contributions by a member to the understanding of intelligence. Originally a physicist, and having served as a military intelligence officer and business executive, he now consults, lectures, and writes about whatever he thinks would be fun.
Dr. Karl Albrecht
Author, "Practical Intelligence: the Art and Science of Common Sense"