Among Carl Jung’s most notable contributions to personality psychology was his proposition of eight functions—four introverted and four extraverted. As explained in his classic work, Psychological Types, each of the basic functions—Thinking, Feeling, Sensing, and Intuition—can take on an introverted or extraverted orientation (e.g., Extraverted and Introverted Intuition) which influences the nature of its workings and productions.
If you consider yourself a personality junkie, you may already be familiar with the 8 cognitive functions. But while I was out for a leisurely stroll this past week, playfully pondering the foundations of typology, my interest turned to the following question:
Why should an introverted function, such as Introverted Thinking (Ti), differ in any significant way from its extraverted counterpart (Te)?
It wasn’t obvious to me, at least at first blush, that they should differ much at all. With my curiosity piqued, I decided to postpone further inquiry until I had time to explore this issue a bit more carefully in writing. Here’s what came to mind.
A Starting Point
A number of theorists have proposed that what we have come to know as human “thought” is essentially inhibited speech. From a functions perspective, we might say, for example, that Ti is what we get when we inhibit Te.
This squares nicely with one of the more common adjectives used to describe Introverts: inhibited. Not only are Introverts inhibited in their body, mannerisms, and appearance, but also their thoughts, feeling, and intuitions. Rather than immediately sharing what comes to mind in an extraverted manner, they prefer to first explore it in the privacy of their own minds.
But how might this inner processing, as accomplished by the introverted (I) functions, differ from the external (E) processing of the extraverted functions? Why would thinking about an idea be any different from talking about it?
One difference Jung outlined was the notion that Extraverts (along with the extraverted functions) are habitually attuned to external “objects”—things in the outside world that we all have ready access to (i.e., the object-ive world). Introverts (and the introverted functions), by contrast, devote more focus and energy to the happenings of their own subject-ive world. In other words, Jung was arguing that the E and I functions have markedly different interests and tend to allocate their attention accordingly.
Skeptics of this view might reference, for example, introverted and extraverted scientists showing interest in, and attending to, pretty much the same things—the same data sets, the same scientific problems, etc.—thus casting doubt on Jung’s subjective-objective distinction. Fair enough. I do think Jung was onto something, however, even if it’s not clearly evidenced in all Introverts. Namely, I would agree with Jung that Introverts tend to be more introspective and self-attuned. This appears particularly true for those with at least moderate levels of what the Big Five calls Neuroticism.
As I’ve discussed elsewhere, Neuroticism overlaps significantly with the “Highly Sensitive Person” (HSP) construct and plays a notable role in fostering self-attunement, self-awareness, and self-consciousness among Introverts. So at least for this type of Introvert, Jung was correct to assert that their energy and focus is often self-directed. Such Introverts (along with more introspective Extraverts) are commonly drawn to the arts and humanities, which allows them to explore and integrate their personal reflections and experiences into their work.
How Social Factors Shape the Extraverted vs. Introverted Functions
Perhaps even more consequential is a function’s relationship to social norms and expectations. In operating inwardly and privately, the introverted functions are ostensibly less fettered and more autonomous in their workings.
Going back to our earlier example, a Ti thought, assuming it remains unexpressed, will, at least on its face, have little social consequence. Unconstrained by social guardrails, the thought is free to follow its own natural course. This freedom can lead to interesting and important discoveries, as exemplified in Einstein’s famous “thought experiments.”
But as Jung was acutely aware, if introverted cognition becomes too siloed and detached from the outside world, it can become increasingly bizarre, illusory, or opaque. In describing the Ni dominant type (INJ), for instance, Jung observes:
He makes his life symbolic…but is unadapted to present day reality… His language is not the one currently spoken—it has become too subjective. His arguments lack the convincing power of reason. He can only profess or proclaim. His is “the voice of one crying in the wilderness.”
If most of one’s thoughts are vocalized, as is commonly seen among Extraverts, greater concern must be granted to their appropriateness in order to earn social favor or avoid punishment. The extraverted functions can therefore be seen as more heavily governed by social norms, customs, and feedback.
We shouldn’t take this to mean that Extraverts habitually pause to reflect before speaking in order to self-check for social appropriateness (this sort of self-consciousness is more characteristic of Introverts). Rather, Extraverts’ understanding of social expectations is developed and internalized quite early in life. So by the time they reach, say, young adulthood, its mostly become second nature. This internalized social understanding is baked into whatever function is most preferred by the Extravert—be it Thinking (Te), Feeling (Fe), Intuition (Ne), or Sensing (Se)—reflexively shaping their words and actions. The functions will therefore bear the marks of the particular family and culture in which they’ve been groomed.
Of course, it’d be foolish to suggest that Introverts aren’t also influenced, to some extent, by social norms. They too develop an internal model of social norms and expectations—a superego, to use Freud’s term. Indeed, Introverts with a robust superego (e.g., ISJs) may be largely resistant to exploring, even inwardly, countercultural ideas, values, or lifestyles.
Nevertheless, the notion of the introverted functions being more shielded from cultural pressures, especially during the “incubation phase” of an idea, seems to have some merit. While Extraverts are arguably more routinely and spontaneously creative, many of history’s most original and revolutionary ideas were hatched in the crucible of an introverted mind.
The Role of J-P Preference
Another contributing factor to differences in the E and I functions is the J-P preference. In my view, type theorist Lenore Thomson has offered the most cogent and compelling explanation for this phenomenon.
According to Thomson, the J-P preference effectively determines (or indicates) whether a given function is more left or right-brained. Since the J preference is more reflective of left-brain operations, and J types lead with either an Introverted Perceiving (Si or Ni) or Extraverted Judging (Te or Fe) function, these functions (Si, Ni, Te, Fe) are seen as having a more left-brained character. Thomson conceives the remaining four functions—Se, Ne, Ti, Fi—as more right-brained.
We encourage you to explore the fascinating topic of hemispheric differences further in the following posts:
INFJ, INTJ, ISFJ & ISTJ Types: Similarities, Differences & the Brain
Left vs. Right Brain: Paths to Meaning & Personality Type Differences
Learn more about Introverts, Extraverts, and the 8 cognitive functions in our books:
My True Type | The 16 Personality Types