With all due respect, this must be one of the most groundless theories in the social sciences since Keynes famously mis-predicted the 15-hour work week. It is the “brain child” of Jennifer O. Grimes, a “Millennial” prospective psychologist bent on finally cracking the “introvert” walnut. She has developed an “energy theory” according to which introversion and extraversion can be related to fleeting self-representations (“If you think about planning and really putting together something in your mind, that could be argued to be introversion. But unless you act and channel the energy outward, it's not bringing to extroverted observable fruition the introverted plan.”); or the personality traits of introverts (if we take these to be a bit less transient) would place them on (or very close to) the autism spectrum – just dial these qualities up a bit, and you will get into typical Asperger’s symptoms. This is, I must say, a very extroverted way of analyzing introversion.
There is, indeed, a lot of confusion around the “introvert” label – to the point where people like Barack Obama and Angela Merkel (who learned to walk down stairs when she was 5 year sold), or even Mitt Romney, are labeled introverts. There have been all sorts of theories, going back to Jung and Eisenck – so here is mine. My hunch is that what sets “introverts” apart is mostly a degree of affective and visceral sensitivity/attunement – so individuals who are socially detached are not necessarily “introverts.”
Of course, this would be incomprehensible to extroverts – who also have a hard time making any categorical qualitative distinctions. Here is Grimes again, advancing the standard utilitarian argument. In her view, individuals “invest” in social interactions only when they think they will get a good “return”on these: “There are people who like to invest a lot of energy and get a lot back. Some people don't want to invest a lot and don't expect a lot back. The people who are deemed the extroverts in pop literature, the people who are social butterflies, what they get back on an interpersonal level is sufficient for them.” Indeed, there is no limit to the extent of rationalization extroverts can engage in – and receive all sorts of credit for it. I am wondering if Steven Levitt could be a closeted introvert, too. And, by the way, how would Grimes classify herself?