Web pages that link to this post usually consist of a discussion thread whose participants’ views of the post vary from “I told you so” to “that doesn’t square with me/my experience” or “MBTI is all wet because…”. Those who take the former position tend to be persons of above-average intelligence whose MBTI types correlate well with high intelligence. Those who take the latter two positions tend to be persons who are defensive about their personality types, which do not correlate well with high intelligence. Such persons should take a deep breath and remember that high intelligence (of the abstract-reasoning-book-learning kind measured by IQ tests) is widely distributed throughout the population. As I say below, ” I am not claiming that a small subset of MBTI types accounts for all high-IQ persons, nor am I claiming that a small subset of MBTI types is populated entirely by high-IQ persons.” All I am saying is that the bits of evidence which I have compiled suggest that high intelligence is more likely — but far from exclusively — to be found among persons with certain MBTI types.
The correlations between intelligence, political leanings, and happiness are admittedly more tenuous. But they are plausible.
IQ AND PERSONALITY
A few years ago I came across some statistics about the personality traits of high-IQ persons (those who are in the top 2 percent of the population).* The statistics pertain to a widely used personality test called the Myers-Briggs Type Indicator (MBTI), which I have taken twice. In the MBTI there are four pairs of complementary personality traits, called preferences: Extraverted/Introverted, Sensing/iNtuitive, Thinking/Feeling, and Judging/Perceiving. Thus, there are 16 possible personality types in the MBTI: ESTJ, ENTJ, ESFJ, ESFP, and so on. (For an introduction to MBTI, summaries of types, criticisms of MBTI, and links to other sources, see this article at Wikipedia. A straightforward description of the theory of MBTI and the personality traits can be found here. Detailed descriptions of the 16 types are given here.)
In summary, here is what the statistics indicate about the correlation between personality traits and IQ:
A person who encountered this post when it was at Liberty Corner claims that “one would expect to see the whole spectrum of intelligences within each personality type.” Well, one does see just that, but high intelligence is skewed toward the five types listed above. I am not claiming that a small subset of MBTI types accounts for all high-IQ persons, nor am I claiming that a small subset of MBTI types is populated entirely by high-IQ persons.
- Other personality traits being the same, an iNtuitive person (one who grasps patterns and seeks possibilities) is 25 times more likely to have a high IQ than a Sensing person (one who focuses on sensory details and the here-and-now).
- Again, other traits being the same, an Introverted person is 2.6 times more likely to have a high IQ than one who is Extraverted; a Thinking (logic-oriented) person is 4.5 times more likely to have a high IQ than a Feeling (people-oriented) person; and a Judging person (one who seeks closure) is 1.6 times as likely to have a high IQ than a Perceiving person (one who likes to keep his options open).
- Moreover, if you encounter an INTJ, there is a 22% probability that his IQ places him in the top 2 percent of the population. (Disclosure: I am an INTJ.) Next are INTP, at 14%; ENTJ, 8%; ENTP, 5%; and INFJ, 5%. (The next highest type is the INFP at 3%.) The five types (INTJ, INTP, ENTJ, ENTP, and INFJ) account for 78% of the high-IQ population but only 15% of the total population.**
- Four of the five most-intelligent types are NTs, as one would expect, given the probabilities cited above. Those same probabilities lead to the dominance of INTJs and INTPs, which account for 49% of the Mensa membership but only 5% of the general population.**
- Persons with the S preference bring up the rear, when it comes to taking IQ tests.**
I acknowledge reservations about MBTI, such as those discussed in the Wikipedia article. An inherent shortcoming of psychological tests (as opposed to intelligence tests) is that they rely on subjective responses (e.g., my favorite color might be black today and blue tomorrow). But I do not accept this criticism:
[S]ome researchers expected that scores would show a bimodal distribution with peaks near the ends of the scales, but found that scores on the individual subscales were actually distributed in a centrally peaked manner similar to a normal distribution. A cut-off exists at the center of the subscale such that a score on one side is classified as one type, and a score on the other side as the opposite type. This fails to support the concept of type: the norm is for people to lie near the middle of the subscale.[6][7][8][33][42]Why was “it was expected” that scores on a subscale (E/I, S/N, T/F, J/P) would show a bimodal distribution? How often does one encounter a person who is at the extreme end of any subscale? Not often, I wager, except in places where such extremes are likely to be clustered (e.g., Extraverts in acting classes, Introverts in monasteries). The cut-off at the center of each subscale is arbitrary; it simply affords a shorthand characterization of a person’s dominant traits. But anyone who takes an MBTI (or equivalent instrument) is given his scores on each of the subscales, so that he knows the strength (or weakness) of his tendencies.
Regarding other points of criticism: It is possible, of course, that a person who is familiar with MBTI tends to see in others the characteristics of their known MBTI types (i.e., confirmation bias). But has that tendency been confirmed by rigorous testing? Such testing would examine the contrary case, that is, the ability of a person to predict the type of a person whom he knows well (e.g., a co-worker or relative). The supposed vagueness of the descriptions of the 16 types arises from the complexity of human personality; but there are differences among the descriptions, just as there are differences among individuals. If only half of the persons who take the MBTI are able to guess their types before taking it, does that invalidate MBTI or does it point to a more likely phenomenon, namely, that introspection is a personality-related trait, one that is more common among Introverts than Extraverts. A good MBTI instrument cuts through self-deception and self-flattery by asking the same set of questions in many different ways, and in ways that do not make any particular answer seem like the “right” one.
My considerable exposure to high-IQ scientists in 30 years of working with them is suggestive. Most of them seemed to exhibit the traits of INTJs and INTPs. And those who took an MBTI test were found to be INTJs and INTPs.
IQ AND POLITICS
It is hard to find clear, concise analyses of the relationship between IQ and political leanings. I offer the following in evidence that very high-IQ individuals lean strongly toward libertarian positions.
The Triple Nine Society (TNS) limits its membership to persons with IQs in the top 0.1% of the population. In an undated survey (probably conducted in 2000, given the questions about the perceived intelligence of certain presidential candidates), members of TNS gave their views on several topics (in addition to speculating about the candidates’ intelligence): subsidies, taxation, civil regulation, business regulation, health care, regulation of genetic engineering, data privacy, death penalty, and use of military force.
The results speak for themselves. Those members of TNS who took the survey clearly have strong (if not unanimous) libertarian leanings.
THE BOTTOM LINE
If you are very intelligent — with an IQ that puts you in the top 2% of the population — you are most likely to be an INTJ, INTP, ENTJ, ENTP, or INFJ, in that order.
* * *
Footnotes:* I apologize for not having documented the source of the statistics that I cite here. I dimly recall finding them on or via the website of American Mensa, but I am not certain of that. And I can no longer find the source by searching the web. I did transcribe the statistics to a spreadsheet, which I still have. So, the numbers are real, even if their source is now lost to me.
** Estimates of the distribution of MBTI types in the U.S. population are given in two tables on page 4 of “Estimated Frequencies of the Types in the United States Population,” published by the Center for Applications of Psychological Type. One table gives estimates of the distribution of the population by preference (E, I, N, S, etc.). The other table give estimates of the distribution of the population among all 16 MBTI types. The statistics for members of Mensa were broken down by preferences, not by types; therefore I had to use the values for preferences to estimate the frequencies of the 16 types among members of Mensa. For consistency, I used the distribution of the preferences among the U.S. population to estimate the frequencies of the 16 types among the population, rather than use the frequencies provided for each type. For example, the fraction of the population that is INTJ comes to 0.029 (2.9%) when the values for I (0.507), N (0.267), T (0.402), and J (0.541) are multiplied. But the detailed table has INTJs as 2.1% of the population. In sum, there are discrepancies between the computed and given values of the 16 types in the population. The most striking discrepancy is for the INFJ type. When estimated from the frequencies of the four preferences, INFJs are 4.4% of the population; the table of values for all 16 types gives the percentage of INFJs as 1.5%.
Using the distribution given for the 16 types leads to somewhat different results:
- There is a 31% probability that an INTJ’s his IQ places him in the top 2 percent of the population. Next are INFJ, at 14%; ENTJ, 13%; and INTP, 10%. (The next highest type is the ENTP at 4%.) The four types (INTJ, INFJ, ENTJ, AND INTP) account for 72% of the high-IQ population but only 9% of the total population. The top five types (including ENTPs) account for 78% of the high-IQ population but only 12% of the total population.
- Four of the five most-intelligent types are NTs, as one would expect, given the probabilities cited earlier. But, in terms of the likelihood of having an IQ, this method moves INFJs into second place, a percentage point ahead of ENTJs.
- In any event, the same five types dominate, and all five types have a preference for iNtuitive thinking.
- As before, persons with the S preference generally lag their peers when it comes to IQ tests.
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