Introversion and extroversion have nothing to do with shyness or how outgoing you are. It has to do with where you derive energy and I disagree with the author of the linked article that introverts just need to practice social interaction. As the book points out, introversion and extroversion can be determined very early in life, she mentions a study where infants who were more reactive to stimulus turned out to be introverts and infants who were chill turned out to be extroverts:
“The four-month-olds who thrashed their arms like punk rockers did so not because they were extroverts in the making, but because their little bodies reacted strongly—they were “high-reactive”—to new sights, sounds, and smells,” Cain writes. “The quiet infants were silent not because they were future introverts—just the opposite—but because they had nervous systems that were unmoved by novelty.” These “high-reactive” babies grow up to be children who need a lot of time to decompress after school, need time alone to be creative and explore. They are introverts, not anti-social, Cain explains. There is a big difference.
I derive my energy from food and sleep ... Jokes aside, I have no clue what people are talking about when they say this. I don't feel energized by talking to people, and I don't feel energized by doing alone-time activities. I don't even see what energy has anything to do with having or not having interaction.
I also don't think "deriving energy" is anywhere near being a measurable scientific event but rather an ill-defined handwavy concept.
I might be mistaken for the non-energy model of an extrovert during one of these sessions, obviously being e.g. shy or retiring wouldn't work, nor is that in my nature.
The difference I perceived between my extroverted salesmen partners and myself was that I wasn't good for much of anything the next day, as I "recharged my batteries" or whatever you want to call it; call it an "ill-defined handwavy concept" not particularly "a measurable scientific event", but I know my productivity, how it works and doesn't, going back to long before I became a programmer. So I firmly believe this phenomena exists, even if you yourself are in-between both of these "types".
Energy is a metaphor for the "stress level," of the individual for lack of a better term.
On my last test, the facilitator explained the energy/stress aspect with a number of examples like your dinner party. She also mentioned people are naturally one or the other, not 50/50.
I realized that my natural inclination was introversion. I believe that what I perceived as my extroverted side was learned through a social upbringing to engage others, which is beneficial. There are a number of social/extroverted things that I sincerely enjoy but I walk away exhausted.
I guess what I'm saying is that it's not so much that one side is a source of energy. It's just normal. It's more that the opposite side is draining.
Extraverts are described as being "higher energy" rather than getting energy from X rather than Y.
As I understand it, the big five is one of the better regarded personality measures among personality psychologists, and "Extraversion" (sic.) is one of the measures. Psychological measures are generally better regarded if they produce more repeatable results (Briggs-Meyers, which despite being discredited is still popular, also uses a -- somewhat different -- extroversion scale).
Wikipedia states that the 'energy explanation' is a characterization by a few popular writers: "Some popular writers have characterized introverts as people whose energy tends to expand through reflection and dwindle during interaction." - Wikipedia (Introvert)
I've seen the 'energy explanation' repeated in social media like hundreds of times. They start by saying that everyone who belives that introversion is the opposite of extroversion is false, even though they're themselves focusing on a theory fully supported only by popular writers.
Perhaps in 10 years the classical definition of the word 'introvert' is lost and the 'energy explanation' wins, because for some reason it spreads like wildfire in social media. My own gut-feeling is that 'introvertism' has been high-status social quality in certain social circles (e.g. 'nerds'), and now some people feel like they want to attribute it to themselves.
If I spend a day with people outside my close friends and family, I definitely need some "quiet time" to recover. For instance, on work trips to another office you invariably get invited out for dinner/drinks after the working day, and I'd much rather sit in my hotel room eating roomservice.
They don't get particularly "recharged" in that vague sense, but they never get discharged by the opposite either.
This is, of course, not a useful thing to point out to someone who is weak (or an introvert). I am a firm believer in two things: Carol Dweck's idea of the "growth mindset", and that our energy is best spent on things we can control and not on things we cannot. Introverts can train themselves to have social interactions drain them less. They may never be loquacious, but good enough is good enough.
At a certain level, it feels like there is a social bloc with a plurality, who pressures all other groups to conform for its convenience. I don't feel the need to do that. Expecting me to act like them makes about as much sense as me expecting them to learn to juggle on a unicycle, or fly model aircraft, or play a particular game, or read books by a certain author, or practice hobby gunsmithing, or perform amateur stand-up comedy.
Why? Why would anyone expect an "introvert" to pretend to be more like "extroverts"? What they should be doing is socializing in a non-painful way with people who share their interests.
"Introverted" and "extroverted" refer to the external behavioral differences that one can use to categorize people. "Introvert" and "extrovert" are different terms and more refer to people's mental focus, or Jung's explanation of where they get their mental energy. But you can't conflate the two. The most talkative person I've known classified himself as a introvert. I, on the other hand, can be extroverted, but I don't particularly like people nor do I get so much out of interacting with them that I feel compelled to be extroverted. In other words, "introverted extroverts" are the shy people - "introverted introverts" don't really give a damn.
But the OP's article is certainly useful; I'd say he just needs to be more precise about the terms he uses and how it's primarily about the behavioral aspects of interacting with people. The idea that it is "draining" to use underdeveloped skills made sense to me.
And might as well mention that asocial is a more fitting word than anti-social if the intent is to describe lack of willingness to participate in social environments. "Anti-social" is better if one is describing behaviour that is socially destructive, like violence.
<insert "but languages evolve" reply here>