Intelligence isn’t as important as you think

Our society gives a lot of weight to intelligence. Academics may have been arguing for a hundred years over what, exactly, intelligence is, but ‘everyone knows’ what it means to be smart, and who is smart and who is not — right?

Of course, it’s not that simple, and the ins and outs of academic research have much to teach us about the nature of intelligence and its importance, even if they still haven’t got it all totally sorted yet. Today I want to talk about one particular aspect: how important intelligence is in academic success.

First of all, to simplify the discussion, let’s start by pretending that intelligence equals “g” and is measured by IQ testing. (“g” stands for “general factor”, and reflects the shared element between multiple cognitive tests. It is a product of a statistical technique known as factor analysis, which measures the inter-correlation between scores on various cognitive tasks. It is no surprise to any of us that cognitive tasks should be correlated — that people who do well on one task are likely to do well on others, while people who do poorly on one are likely to perform poorly on others. No surprise, either, that some cognitive tasks will be more highly correlated than others. But here’s the thing: the g factor, while it explains a lot of the individual differences in performance on an IQ test, accounts for performance on some of the component sub-tests better than others. In other words, g is more important for some cognitive tasks than others. Again, not terribly unexpected. Some tasks are going to require more ‘intelligence’ than others. One way of describing these tasks is to say that they are cognitively more complex. In the context of the IQ test, the sub-tests each have a different “g-loading”.)  

Now there is no doubting that IQ is a good predictor of academic performance, but what does that mean exactly? How good is ‘good’? Well, according to Flynn, IQ tests that are heavily-loaded on g reliably predict about 25% of the variance in academic achievement (note that this is about variance, that is the differences between people; this is not the same as saying that IQ accounts for a quarter of academic performance). But this does vary significantly depending on age and population — for example, in a group of graduate students, the relative importance of other factors will be greater than it is in a cross-section of ten-year-olds. In the study I will discuss later, the figure cited is closer to 17%.

Regardless of whether it’s as much as 25% or as little as 17%, I would have thought that these figures are much smaller than most people would imagine, given the weight that we give to intelligence.

So what are the other factors behind doing well at school (and, later, at work)?

The most obvious one is effort. One way to measure how hard people work is through the personality dimension of Conscientiousness.

One study involving 247 British university students compared the predictive power of the “Big Five” personality traits (Neuroticism, Extraversion, Openness to Experience, Agreeableness, Conscientiousness) on later exam performance, and found that Conscientiousness had a significant effect, and was the only trait to have a significantly positive effect. Illuminatingly, of Conscientiousness’s components (Competence, Order, Dutifulness, Achievement striving, Self-discipline, Deliberation), only Dutifulness, Achievement striving, and (to a lesser extent), Self-discipline, had significant effects.

There were also, smaller and less reliable, negative effects of Neuroticism and Extraversion. The problems here came mainly from Anxiety and Impulsiveness, and Gregariousness and Activity.

Overall, Dutifulness, Achievement striving, and Activity, accounted for 28% of the variance in overall exam grades (over the three years of their undergraduate degrees).

But note that these students were highly selected — undergraduates were (at this point in time) accepted to the University College London at an application: acceptance ratio of 12:1 — so IQ is going to be less important as a source of individual difference.

In another study by some of the same researchers, 80 sixth-formers (equivalent to grade 10) were given both personality and intelligence tests. Conscientiousness and Openness to Experience were found to account for 13% of unique variance in academic performance, and intelligence for 10%. Interestingly, there were subject differences. Intelligence was more important than personality for science subjects (including math), while the reverse was true for English language (literature, language) subjects.

The so-called Big Five personality dimensions are well-established, but recently a new model has introduced a sixth dimension: Honesty-Humility. Unexpectedly (to me at least), a recent study showed this dimension also has some implications for academic performance.

The first experiment in this study involved 226 undergraduate students from a School of Higher Education in the Netherlands. Both Conscientiousness and Honesty-Humility were significantly and positively correlated to grade point average (with Conscientiousness having the greater effect). All the components of Conscientiousness (in this model, Organization, Diligence, Perfectionism, Prudence) were significantly related to GPA. Three of the four components of Honesty-Humility (Greed Avoidance, Modesty, Fairness) were significantly related to GPA (in that order of magnitude).

In the second experiment, a wider data-set was used. 1262 students from the same school were given the Multicultural Personality Test—Big Six, which measures Emotional Stability, Conscientiousness, Extraversion, Agreeableness, Openness, and Integrity (a similar construct to Honesty-Humility, involving the facets Honesty, Sincerity, Greed Avoidance). Again, Conscientiousness and Integrity showed significant and positive correlations to GPA. In this case, Conscientiousness was divided into Need for Rules and Certainty, Orderliness, Perseverance, and Achievement Motivation — all of which were separately significant predictors of GPA. For Integrity, Greed Avoidance produced the largest effect, with Honesty being a smaller effect but still highly significant, while Sincerity was of more marginal significance.

In summary, personality traits such as Diligence, Achievement Motivation, Need for Rules and Certainty, Greed Avoidance, and Modesty, were the traits most strongly associated with academic performance.

Of course, one flaw in personality tests is that they rely on self-reports. A much-discussed longitudinal study of eighth-graders found that self-discipline accounted for more than twice as much variance as IQ in final grades. Moreover, self-discipline also predicted which students would improve their grades over the course of the year, which IQ didn’t.

Again, however, it should be noted that this is a selected group — the students came from a magnet public school in which students were admitted on the basis of their grades and test scores.

This study measured self-discipline not only by self-report, but also by parent report, teacher report, monetary choice questionnaires (in an initial experiment involving 140 students), a behavioral delay-of-gratification task, a questionnaire on study habits, (in a replication involving 164 students).

One personality trait that many have thought should be a factor in academic achievement is Openness to Experience, and indeed, in some experiments it has been so. It may be that Openness to Experience, which includes Fantasy (vivid imagination), Aesthetic Sensitivity, Attentiveness to Inner Feelings, Actions (engagement in novel activities), Ideas, and Values (readiness to reexamine traditional values), is associated with higher intelligence but not necessarily academic success (depending perhaps on subject?).

It may also be that, as with Neuroticism, Extraversion, and Conscientiousness, only some (or even one) of the component traits is relevant to academic performance. The obvious candidate is Ideas, described as the tendency to be intellectually curious and open to new ideas. Supporting this notion, recent research provides evidence that Openness incorporates two related but distinct factors: Intellect (Ideas) and Openness (artistic and contemplative qualities, embodied in Fantasy, Aesthetics, Feelings, and Actions), with Values a distinct marker belonging to neither camp.

A recent meta-analysis, gathering data from studies that have employed the Typical Intellectual Engagement (TIE) scale (as a widely-used proxy for intellectual curiosity), has found that curiosity had as large an effect on academic performance as conscientiousness, and together, conscientiousness and curiosity had as big an effect on performance as intelligence.

Of course, while research has shown (not unexpectedly) that Conscientiousness and Intelligence are quite independent, the correlation between Intelligence and Curiosity is surely significant. In fact, this study found a significant correlation between both TIE and Intelligence, and TIE and Conscientiousness. Nevertheless, the best-fit model indicated that all three factors were direct predictors of academic performance.

More to the point, these three important attributes all together still accounted for only a quarter of the variance in academic performance.

Regardless of the precise numbers (this area of study depends on complex statistical techniques, and I wouldn’t want to rest any case on any specific figure!), it is clear from the wealth of research (which I have barely touched on), that although intelligence is an important attribute in determining success in the classroom and in employment, it is only one among a number of important attributes. And so is Diligence. Perhaps we should spend less time praising intelligence and hard work, and more time encouraging engagement and curiosity, and a disinterest in luxury goods or a high social status.

 

Read more about the curiosity study at https://medicalxpress.com/news/2011-10-curiosity-doesnt-student.html