IQ and Personality
I recently 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). In the MBTI there are four pairs of complementary personality traits (which I sketch below): 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.
In summary, here's what the statistics indicate about the correlation between personality traits and IQ:
Other personality traits being the same, an iNtuitive person (one who grasps patterns and seeks possibilities) is 27 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 8 times more likely to have a high IQ than one who is Extraverted; a Thinking (logic-oriented) person is 2.5 times more likely to have a high IQ than a Feeling (people-oriented) person; and a Judging person (one who seeks closure) is about twice 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 (Introverted, iNtuitive, Thinking, Judging), there is a 37% probability that his IQ places him in the top 2 percent of the population. The probability is 20% for an INTP, 15% for an INFJ, and 8% for an INFP. These four types account for 66% of the high-IQ population but only 6% of the total population.
Think about that, then think of all those people out there who chatter mindlessly on their cell phones, watch TV incessantly (especially daytime TV and "reality" shows), "hang out", and just can't seem to "get it together". It's frightening to be surrounded by all those stupid people -- and most of them are liberals.**
P.S. Here is an insightful comment:
IQ tests typically involve a certain kind of puzzle solving, and it seems to me that the people who do particularly well on IQ tests are those who have the kind of personality that enjoys puzzle solving. And the people who make IQ tests are also people who enjoy puzzle solving, and who believe that puzzle solving is an important and valuable ability (i.e., they are passionate about puzzle solving, interpreted in a very general sense). Essentially, an IQ test measures the overlap between the passions of the test taker and the passions of the test maker. (Peter Turney, writing at Apperceptual on May 27, 2008)
IQ and Politics
The Right Is Smarter Than the Left
Republicans Are Happier Than Democrats
* August 26, 2007: 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 Mensa USA, 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. Moreover, the numbers jibe well with what I observed in many years of working with high-IQ scientists, most of whom exhibited the traits of an INTJ or INTP.
UPDATE (03/15/08): One person writes that IQ and MBTI scores
are orthogonal concepts with significant amounts of independence. Despite what the data says above, one would expect to see the whole spectrum of intelligences within each personality type. FWIW and among other things, Wiki is critical of both the validity and reliability of
the MBTI test http://en.wikipedia.org/wiki/Myers-Briggs_Type_Indicator.
The conceptual independence of IQ and MBTI makes the high correlation between Introversion and high IQ all the more compelling, to me. I do not know why "one would expect to see the whole spectrum of intelligences within each personality type." That strikes me as an a priori argument, not an empirical one. The high correlation between Introversion and IQ makes intuitive sense, as well. That is, Introverts, instead of expending a lot of time expressing their thoughts and emotions, spend a lot of time gathering and integrating information (much of it arcane to the average person). One result of that tendency is the ability to do well on the kinds of tests that measure IQ. I acknowledge reservations about MBTI, such as those stated 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), yet individual MBTI scores are not notably volatile.
I do not find it problematic that, according to the Wikipedia article,
it was expected that scores would show a bimodal distribution with peaks near the ends of the scales. However, scores on the individual subscales are actually distributed in a centrally peaked manner similar to a normal distribution. A cut-off exists at the centre 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. 
I don't understand why "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's 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). It's also possible that we see what there is to be seen in others. The supposed vagueness of MBTI descriptions 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 point to a more likely phenomenon, namely, that most persons (especially Extraverts) aren't introspective? 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.
** Before you take exception to the proposition that most of the stupid people are liberals, follow the link to "IQ and Politics" (and the link therein), and read "The Right Is Smarter Than the Left."
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Updated on Tuesday, 15 December 2015 18:39:57