The more I examine the more confusing it is.

We've had no consensus in discussions here about introversion. We're not shy or socially — except some of us are. Some of us like people, some of us would prefer to spend time with a book, thank you very much. Some of us the telephone, some of us dislike the telephone, some of us don't mind it. Some of us can behave as extroverts, some don't bother. And then there's psychologist Elaine N. Aron's theory about the Highly Sensitive Person, which seems a bit of an outlier in terms of introversion.

And the whole energy discussion — about how being with people drains us while it energizes extroverts — is compelling, but nobody has really been able to pin down empirically what that means. What is energy, in this context?

Well, a very interesting young thinker, Jennifer O. Grimes, has noticed this too. We've already heard Grimes' energy theory, and we've heard from her mentor, Jonathan M. Cheek, at Wellesley.

Grimes has a master's in interdisciplinary studies, combining , , psychology. She is currently a research assistant at Wellesley and Harvard, and she continues puzzling over introversion.

"There is such a struggle at what is at the core of introversion/ ," Grimes told me in a recent interview. "What we were noticing was a popular movement to bring a little more clarity to the definition, but there's not been an awful lot of psychometric work with that."

Grimes is all for the introvert-positive movement, to which this blog belongs. "I like its goal, " she says. "But I'm not sure I like so much how it pulls it off, because some of the literature reads like an idiosyncratic account of a personal experience."

Grimes, Cheek, and researcher Julie K. Norem (who also has done wonderful research into pessimism) started trying to tease apart all the various definitions we see of introversion. They did a literature review and examined existing measurement tools — such as Marti Olsen Laney's introversion scale. "I did a factor analysis of Laney's scale," Grimes says. "It really tests psychometrically as a scale."

Grimes, Cheek, and Norem developed a four-factor model of introversion, dividing it into Social Introversion (prefers solitude to people); Thinking Introversion (reflective and introspective); Anxious Introversion (shy and ruminative); and Inhibited Introversion (resists new experiences).

That's interesting enough, but where Grimes went next in her exploration of introversion is compelling, likely to be controversial, and quite possibly right on the money — research (someday) will tell.

In her master's thesis, Grimes posits that introversion is not the opposite of extroversion, but that they are two different traits altogether. And she proposes something that has come up here from time to time: that introversion actually is on the scale.

Grimes' thesis explains that if you take each of the factors this new model proposes and follow it along a continuum to their most extreme expressions, they correlate with the widely used Baron-Cohen Autism Spectrum Quotient.

Depending on how much we have of each factor (and how they interact with other traits), we can be simply introverted or, moving along the continuum, have or, moving further yet, have autism.

Consider, for example, that many of us tend to think slowly and are not quick at communicating. At the introvert level, no big deal. Take that communication difficulty and move it along the scale Grimes proposes and you get to and then autism.

Same with our tendency to focus deeply: At the healthy end of the scale that can be perseverance. Take it further, and you hit perseveration, which is not so good.

Grimes suspects Aron's sensitivity theory is outside of introversion. "That sounds like it belongs more in , the tendency to become frazzled and overwhelmed coupled with physical sensitivity is its own thing."

Grimes' theory is an interesting approach to pinning down the slippery definition of introversion and, she says, it might help us gain deeper understanding of autism. "There are some things we haven't yet figured out about autism that we have figured out about introversion. Introverts who do spend a lot of time in introspection have a good account of what it's like. We could use the studies that we've done so far, with both areas, to perhaps scaffold each other."

Is this theory disparaging to introverts? Not to my mind, not at all. We fret about being misunderstood, and if this opens doors to deeper understanding into our ways, that's good. It would explain the phenomenon of the "extroverted introvert" or the "swashbuckling introvert" (as readers here have described themselves). It eases the polarized attitudes we sometimes see between introverts and extroverts. And it might help further acceptance of our way of being and start chipping away at the concept of extroverts being "happier" and better at socializing. If you're a Temple Grandin fan, as I am, it's a lot easier to accept autism as a different way of being rather than, necessarily, a lesser way.

It also raises another fascinating question: If introversion requires its own scale, it follows that extroversion does too. And if autism is on one far end of the introversion scale, what's on the far end of an extroversion scale? ? ? Lady Gaga?

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