This post is a collection and refinement of related posts at my earlier blog, Liberty Corner (with updated links). Each section of this post carries the same title as the original post at Liberty Corner. “IQ and Personality” is and has been, by far, the most popular of my Liberty Corner posts, so I give the eponymous section the place of honor in this post.
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.
Leftists who proclaim themselves to be more intelligent than persons of the right do so, in my observation, as a way of reassuring themselves of the superiority of their views. They have no legitimate basis for claiming that the ranks of highly intelligent persons are dominated by the left. Leftist “intellectuals” in academia, journalism, the “arts,” and other traditional haunts of leftism are prominent because they are vocal. But they comprise a small minority of the population and should not be mistaken for typical leftists, who seem mainly to populate the ranks of the civil service, labor unions, the teaching “profession,” and the unemployed. (It is worth noting that public-school teachers, on the whole, are notoriously dumber than most other college graduates.)
Again, I am talking about general relationships, to which there are many exceptions. If you happen to be an exception, don’t take this post personally. You’re probably an exceptional person.
IQ AND PERSONALITY
Some 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:
- 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.**
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.
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.
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. According to a footnote to an earlier version of the Wikipedia article about MBTI, 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 RIGHT IS SMARTER THAN THE LEFT
I count libertarians as part of the right because libertarians’ anti-statist views are aligned with the views of the traditional (small-government) conservatives who are usually Republicans. Having said that, the results reported in “IQ and Politics” lead me to suspect that the right is smarter than the left, left-wing propaganda to the contrary notwithstanding. There is additional evidence for my view.
A site called Personality Page offers some data about personality type and political affiliation. The sample is not representative of the population as a whole; the average age of respondents is 25, and introverted personalities are overrepresented (as you might expect for a test that is apparently self-administered through a web site). On the other hand, the results are probably unbiased with respect to intelligence because the data about personality type were not collected as part of a study that attempts to relate political views and intelligence, and there is nothing on the site to indicate a left-wing bias. (Psychologists, who tend toward leftism, have a knack for making conservatives look bad, as discussed here, here, and here. If there is a strong association between political views and intelligence, it is found among so-called intellectuals, where the herd mentality reigns supreme.)
The data provided by Personality Page are based on the responses of 1,222 individuals who took a 60-question personality test that determined their MBTI types (see “IQ and Personality”). The test takers were asked to state their political preferences, given these choices: Democrat, Republican, middle of the road, liberal, conservative, libertarian, not political, and other. Political self-labelling is an exercise in subjectivity. Nevertheless, individuals who call themselves Democrats or liberals (the left) are almost certainly distinct, politically, from individuals who call themselves Republicans, conservatives, or libertarians (the right).
Now, to the money question: Given the distribution of personality types on the left and right, which distribution is more likely to produce members of Mensa? The answer: Those who self-identify as persons of the right are 15% more likely to qualify for membership in Mensa than those who self-identify as persons of the left. This result is plausible because it is consistent with the pronounced anti-government tendencies of the very-high-IQ members of the Triple Nine Society (see “IQ and Politics”).
REPUBLICANS (AND LIBERTARIANS) ARE HAPPIER THAN DEMOCRATS
Some 45% of all Republicans report being very happy, compared with just 30% of Democrats and 29% of independents. This finding has also been around a long time; Republicans have been happier than Democrats every year since the General Social Survey began taking its measurements in 1972….
Of course, there’s a more obvious explanation for the Republicans’ happiness edge. Republicans tend to have more money than Democrats, and — as we’ve already discovered — people who have more money tend to be happier.
But even this explanation only goes so far. If one controls for household income, Republicans still hold a significant edge: that is, poor Republicans are happier than poor Democrats; middle-income Republicans are happier than middle-income Democrats, and rich Republicans are happier than rich Democrats.
Gallup adds this:
Republicans are significantly more likely to report excellent mental health than are independents or Democrats among those making less than $50,000 a year, and among those making at least $50,000 a year. Republicans are also more likely than independents and Democrats to report excellent mental health within all four categories of educational attainment.
There is a lot more in both sources. Read them for yourself.
Why would Republicans be happier than Democrats? Here’s my thought, Republicans tend to be conservative or libertarian (at least with respect to minimizing government’s role in economic affairs). I refer you to a post in which I discussed Thomas Sowell’s A Conflict of Visions:
He posits two opposing visions: the unconstrained vision (I would call it the idealistic vision) and the constrained vision (which I would call the realistic vision). As Sowell explains, at the end of chapter 2:
The dichotomy between constrained and unconstrained visions is based on whether or not inherent limitations of man are among the key elements included in each vision…. These different ways of conceiving man and the world lead not merely to different conclusions but to sharply divergent, often diametrically opposed, conclusions on issues ranging from justice to war.
Idealists (“liberals”) are bound to be less happy than realists (conservatives and libertarians) because idealists’ expectations about human accomplishments (aided by government) are higher than those of realists, and so idealists are doomed to disappointment.
All of this is consistent with findings reported by law professor James Lindgren:
[C]ompared to anti-redistributionists, strong redistributionists have about two to three times higher odds of reporting that in the prior seven days they were angry, mad at someone, outraged, sad, lonely, and had trouble shaking the blues. Similarly, anti-redistributionists had about two to four times higher odds of reporting being happy or at ease. Not only do redistributionists report more anger, but they report that their anger lasts longer. When asked about the last time they were angry, strong redistributionists were more than twice as likely as strong opponents of leveling to admit that they responded to their anger by plotting revenge. Last, both redistributionists and anti-capitalists expressed lower overall happiness, less happy marriages, and lower satisfaction with their financial situations and with their jobs or housework. (From the abstract of Northwestern Law and Economics Research Paper 06-29, “What Drives Views on Government Redistribution and Anti-Capitalism: Envy or a Desire for Social Dominance?,” March 15, 2011.)
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. Your politics will lean heavily toward libertarianism or small-government conservatism. You probably vote Republican most of the time because, even if you are not a card-carrying Republican, you are a staunch anti-Democrat. And you are a happy person because your expectations are not constantly defeated by reality.
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* 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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