Monday 15 July 2013

Intelligence, personality, and self-knowledge


It has been usual in much of the history of the psychology of individual differences to deal with intelligence and personality in different chapters. Intelligence is about abilities and skills, personality is about emotions, attitudes and behavioural preferences.

Intelligence has one main score, g, and three or four component and subsidiary scores, such as verbal, arithmetical, spatial and processing/memory. You have to take an actual test, and will eventually start to fail items that are too hard for you. No wonder these tests generate visceral reactions. Self rating of genius is not allowed: you have to prove every ability with correct answers.

Personality has five main scores: neuroticism, extraversion, openness to experience, agreeableness and conscientiousness. These were called the Big Five, and represented something of a truce between those who favoured 3 factors and those holding out for 16 factors. Science progresses, but slowly. You have to take a personality test, but you are told “There are no right or wrong items” and there is nothing to prove. This liberal approach generates far less animosity in the general public. Yet, a moments thought about living with people confirms that some are easier to get on with than others. At the very least, ticking a box which says “I don’t particularly care what happens to other people” should raise a scintilla of doubt about whether they would be an agreeable companion on a difficult journey. Some items must be “wrong” in a social sense.

Happily, this obvious point has occurred to brighter minds (Rushton and Irwing, 2011) , who have factor analysed the five factor model and shown that it can be reduced to one dimension: the General Factor of Personality. High scores on this General Factor of Personality indicate a “good” personality; low scores a “difficult” personality (someone who is hard to get along with). Individuals high on the General Factor of Personality are altruistic, agreeable, relaxed, conscientious, sociable, and open-minded, with high levels of well-being and self-esteem. Those with poorer personalities are at the other end of the descriptive spectrum. They would tend to be selfish, disagreeable, anxious, not dependable, unsociable, closed-minded or rigid thinkers, with high levels of distress and low self-esteem.

We are always at liberty to name factors as we wish, and to my mind this could also be labelled “Easy to get along with” versus “Difficult and un-cooperative”. Mind you, not everyone agrees with this simplification. I regard it as performing a public service, in that it ought to help us avoid vexatious people. 

To what extent is personality (as one factor) correlated with intelligence (as one factor)?

Before answering this question, we must note a curious feature of personality assessments: they are all based on self report. Are you a kind and good natured person? I am sure you are. However, I would be more convinced if your colleagues confirmed it privately, rather than that you asserted it on the basis of self-love and selective memory. These facts were borne in on me by many years of using the Belbin system, which seeks to find out what sorts of team roles people habitually adopt when working in groups. Individual self-perceptions were supplemented by at least 4 independent observers. I used to ask for at least 8 observers, who all sent in their observations privately to me. Self-perceptions very rarely coincided with observers’ opinions, (say only 15% of the time) and then usually only when the person concerned had a very clear team role preference. In the end, I only used observer’s assessments, and my clients preferred their feedback when seeking to understand themselves.

Self knowledge has limits. The energy we put into being ourselves reduces our capacity to monitor ourselves. Too much self-knowledge, too much of the time, might endanger our survival.

Curtis Dunkel from Western Illinois University has found a data set from Block and Block (2006) in which children’s personality was rated by assessors and intelligence was assessed concurrently. It is one of those treasure troves which permits interesting research. The sample size of 104 is pretty good bearing in mind they were followed from early childhood, and given face to face Wechsler Intelligence tests, the gold standard for intelligence assessment. Among other findings, the correlation between intelligence at 11 and 18 is an impressive 0.84

Dunkel finds that there is a significant association between intelligence and personality. Stable personality at 18 (as assessed by others) and stable g as derived from the Wechsler Adult Intelligence Test correlate at 0.46 which is substantial as well as being significant. It would seem that being brighter than average goes together with having an agreeable and conscientious attitude.

This puts the cat among the pigeons. We certainly need further studies on externally assessed personality measures, not on self-reported questionnaires, but a confirmation of this result would suggest that Dunkel is right to suggest that they point to the possibility of unification across individual differences in cognitive ability and personality under the banner of life history theory.


Curtis S. Dunkel (2013) The general factor of personality and general intelligence: Evidence for substantial association. Intelligence, In Press.

J. Philippe Rushton and Paul Irwing (2011) The General Factor of Personality: Normal and Abnormal in (Eds)  Tomas Chamorro-Premuzic, Sophie von Stumm and Adrian Furnham. Wiley-Blackwell Handbook of Individual Differences, First Edition. 2011 by Blackwell Publishing Ltd.


  1. People who write about IQ tend to agree it's a excellent predictor of life outcomes. But what about when it's not? What other factors are there?

    I'm fairly high IQ (circa 145), late middle age, with fairly poor life outcomes. I'm an anxious introvert with a checkered employment history and few and poor relationships. I have an older brother and sister with at least as high IQs and even poorer outcomes on some measures. Our father was (is) an anxious introvert with a high IQ (hard science PhD) and a drinking problem. I'm proud that I at least don't have the drinking problem.

    From the kids I knew in gifted classes I would say this is usually true- they came from nice stable families and have had nice lives. I can think of a couple of exceptions besides myself, but they come from known or suspected bad family situations also. I suspect being intelligent is good, but if you come from a bad family situation, it frequently makes things worse.

  2. IQ 145 is 3 sigma, so at 1 in a thousand you have very high intelligence. However, although IQ is an excellent predictor it accounts for (very roughly) about a third of the variance in life outcomes. There have been many proposals at to what accounts for the rest of the variance, but surprisingly little in the way of supportive evidence. Personality, social class, personal attractiveness, motivation..... endless suggestions. Advances in genetics may make the picture clearer, but most of us already know that many of our personal characteristics probably have an impact, sometimes negatively. Anxiety certainly seems to damage talent, if only by reducing confidence and commitment to necessary practice. Linda Gottfredson calls the highest 5% IQ band "Yours to lose". Sometimes we lose it, and don't know why.
    By the way, late middle age is when many people decide to turn to long-postponed projects. A friend of mine became a best selling novelist in her sixties. Might be premature in your case to draw too many conclusions just yet.

  3. "Individuals high on the General Factor of Personality are ..." good spouses and parents? Just wondering. Do they always marry, even?

    1. Don't know about that, but one could probably derive an answer by finding out if there were big five personality differences between the happily and long married on one hand, and the unhappily and short married on the other hand. Also interesting to look at the personality of the never married.

  4. I will have to read up on this, but isn't it an established fact that the big five are given by independent normal distributions? If this is true, is it possible to reconcile this fact with a general factor of personality?

    Here is a literature review:

    Seems very impressive. I thought gfp was just a speculative fringe theory.

    1. Thank you for this interesting reference. In point of fact Caroline Just was writing just at the time that Rushton and Irwing were writing, so we probably need a later paper, though the studies used were already published in both cases. More significantly, the criticism of the general factor (which I have also heard personally from distinguished personality researchers) is that it represents a social desirability effect. It was precisely for that reason I was impressed with the study by Curt using objective assessors. That gets rid of social desirability effects. I really think there is something there. We should drop self report and use observer ratings.

  5. " It would seem that being brighter than average goes together with having an agreeable and conscientious attitude."

    Hmmmph. As a member of Mensa, and having scored a mere 1 point away from qualifying for Intertel, I believe I have some subject matter expertise. Or, at least, subject matter experience. I do not see that high intelligence is either (more than modestly) predictive of either social "agreeableness", or what I would take to be the presumed corollary: success.

    However, the correlation might indeed be the case, between the ages of 11 and 18, when social agreeableness has a much higher individual payoff, and individual expression is still subsumed to a large degree.

    Frankly, I must class myself as one of those who mistrust the lumping together of all those social factors into a single scale. No more than I believe that mental ability IQ is the final arbiter of ability measures. My brother, for instance, was a football wizard, with an extremely high physical "IQ" ability - an ability I could only dream of. But I can think circles around him.

    Still, I have just "run across" your postings/blog - and they are very interesting. Keep up the good work.

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