Are you an introvert? It depends on which book you read. Here’s a sampling of the various conceptualizations of introversion in pop culture : Preference for quiet, minimally stimulating environments: Quiet by Susan Cain Preference for concentration and solitude: The Introvert’s Way by Sophia Dembling Rechargeable battery: The Introvert Advantage by Marti Olsen Laney Thoughtful-introspective
Are you an introvert? It depends on which book you read.
Here’s a sampling of the various conceptualizations of introversion in pop culture :
- Preference for quiet, minimally stimulating environments: Quiet by Susan Cain
- Preference for concentration and solitude: The Introvert’s Way by Sophia Dembling
- Rechargeable battery: The Introvert Advantage by Marti Olsen Laney
- Thoughtful-introspective: Solitude by A. Storr
- Shy-socially anxious: The Gift of Shyness by A. Avila
- Artistic-sensitive-creative: The Highly Sensitive Person by E. Aron
- Literary-observer: Jane Austen, The Complete Novels
- Worried: The Positive Power of Negative Thinking by J. Norem
- Lonely-isolated: Just Your Type by P. Tieger
- Loner-alone by preference: Party of One by A. Rufus
- Low Energy: High Energy Living by R. Cooper
Historically, there has been just as much confusion in the psychological literature. Carl Jung originally defined introversion as a focus on one’s “inwardly directed psychic energy”. However, in the 30s, the psychologist J.P. Guilford showed that various attempts to measure Jung’s conceptualization of introversion resulted in multiple, distinct factors. In other words, there didn’t appear to be a single dimension of personality that captured all of introversion.
In the 60s Patricia Carrigan echoed this point, arguing that introversion was not effectively captured by a single scale. She cautioned that if the phrase introversion is to continue to be used, “care must be taken to specify its conceptual and operational referent. What appear to be minor distinctions between the various conceptions may in fact be crucial ones.” In the 70s, the heated debate continued, with a much older Guilford arguing with H.J. Eysenck over whether introversion can possibly, or even should, be captured by a single scale.
All seemed to be settled in the 90s with the emergence of the “Big Five” framework of personality. The five main factors of personality– extraversion, neuroticism, agreeableness, conscientiousness, and intellect/imagination– were empirically derived based on what patterns of behavior tend to go together within individuals. Under this framework, introversion is merely defined as the opposite of extraversion.
In the Big Five framework, extraversion comprises two main aspects: enthusiasm (reflecting sociability, positive emotions, and warmth) and assertiveness (reflecting the tendency to take charge, become a leader, and captivate attention). The common factor seems to be high sensitivity to rewards in the environment— which due to the highly social nature of humans throughout the course of human evolution, most prominently consists of rewards associated with social attention.
Therefore, under the dominant personality framework in modern psychology, if you score low in enthusiasm and assertiveness, you’re an introvert
Here’s the problem: the Big Five framework forces a definition of introversion onto people, many of whom do not conceptualize introversion in the same way. For instance, one study did a comparison of common-sense/everyday notions of introversion and ‘scientific’ conceptions of introversion. They found that the most prototypical characteristic of introversion, as identified by the general public, was the following item:
Clearly, many people equate introversion with introspection. In the Big Five framework, however, this item is classified as part of the intellect/imagination domain of personality, not the introversion domain. So there’s a serious mismatch between folk definitions of introversion and scientific definitions. People who view themselves as introverted because they are highly introspective are being told by scientists: “You aren’t really introverted based on patterns of covariation among the general population.” To which everyday people rightfully respond: “WTF?” 
As noted personality psychologist Jonathan Cheek told me, “by invalidating the ordinary language meaning of introversion by defining it solely as the opposite of Big Five Extraversion, the Big Five researchers are guilty of Psychological Imperialism .” Influenced by the seminal work of Jung, Guilford, and Carrigan, Cheek and his colleagues have decided to take a different approach, by focusing on the phenomenon of introversion on its own, free from having to be force-fit into one scheme or another.
As Carl Jung said, each individual is ultimately a unique crystal, but type theories can be helpful for navigating social life. Embracing this Jungian philosophy, Cheek and his colleagues argue that when people use the term “introversion”, they should never just use it by itself. Instead, they argue that researchers should put a specific modifier in front of the term. What modifiers could be used?
In her masters thesis (written under the advisement of Cheek), Jennifer Odessa Grimes defined four meanings of introversion: social, thinking, anxious, and restrained (which happens to form the positive acronym STAR). It’s possible to score high or low on either of these flavors of introversion. For instance, you could be low in social introversion by preference but not be particularly anxious in the presence of people. Or you could suffer from crippling social anxiety, but still have the desire to be highly social. Or any other combination of these four meanings of introversion.
By this point you’re probably wondering what kind of introvert you are. Well, you’re in luck. There’s a new test for that.