The theory of fluid and crystallized intelligence was developed by Cattell and Horn (R. B. Cattell, 1941, 1950; 1971; Horn, 1965; Horn & Cattell, 1966), who used factor analysis to show that primary mental abilities such as reasoning ability, word fluency, verbal comprehension, facility with numbers, spatial visualization, and processing speed, can be organised into two principle classes of ability: fluid intelligence and crystallized intelligence. This conceptualization has withstood the test of time, and is widely used in cognitive neuroscience today.

Fluid intelligence (Gf or gF!) broadly captures our general reasoning ability. To quote from Jonassen &  Hopkins (1993): “Gf represents different forms of reasoning including abstracting, forming and using concepts (classification), perceiving and using relations, identifying correlates, maintaining awareness in reasoning, and abstracting ideas, especially from figural and nonverbal… content” (p. 53). It has been described as the source of intelligence that an individual uses when he or she doesn’t already know what to do.

Crystallized intelligence (Gc) describes abilities depending on specific, acquired knowledge or expertise – the result of learning and acculturation. It is measured in tests of expert knowledge, general information, use of language (vocabulary) and is reflected in a wide variety of acquired, specific skills (Horn & Cattell, 1967). Educational and cultural opportunities are central to its development. Working memory capacity is closely related to fluid intelligence, and there is strong evidence that training working memory can improve fluid intelligence (Jaeggi et al, 2008).

People with a high capacity of Gf tend to acquire more Gc knowledge and at faster rates, and this has been called Gf  investment.

Ingrid Schoon (University of London) and her colleagues have just published a remarkable paper looking at the relationship between intelligence and social and political attitudes. The sample of their study was a huge (8804 individuals!) representative sample of the British population born in 1958.  Each individual’s family socio-economic background and intelligence (g) was measured at age 11. Social attitudes and educational and occupational attainment (qualifications and occupational status) were then measured for each of these individuals 22 years later at age 33.  Interestingly, they found a direct association between higher g at 11 and more liberal social attitudes and political trust at age 33. (Having a more ‘liberal social attitude’ means being more anti-racist, socially liberal (tolerant, with and in support of gender equality. Having more ‘political trust’ means having more trust in the country’s liberal democratic political system.) As far as socio-economic status goes, individuals from more privileged backgrounds showed more political trust,  but did not differ in liberal social attitudes from those who came from less privileged backgrounds.

Structural equation model linking general cognitive ability at age 11 to social attitudes at age 33.
Strength of relationship (-1 to +1) for men (n = 4267) are shown on the left and for women (n = 4537) on the right.

This study’s results are consistent with other research showing that higher intelligence tends to be positively correlated with liberalism and negatively correlated with conservatism. A higher intelligence is also associated with the endorsement of alternatives (such as the Liberal ar Green party) to the two main political parties  in the UK (Deary et al., 2008).

Article reference:

Schoon, I., Chenga, H., Gale, C.R., Batty, D. & Deary, I. J. (in press). Social status, cognitive ability, and educational attainment as predictors of liberal social attitudes and political trust. Intelligence.

A technical note.

The technique used in this study is ’structural equation modeling’. It is a ‘model driven’ (rather than exploratory or descriptive) approach, and it is  ’causal’ rather than ‘correlational’ in its emphasis. It is a way of causally modeling the relationships between variables like g and liberal attitudes; it does not simply give you correlations which are difficult to interpret in terms of the underlying ‘causal arrows’.  These causal links between g and liberal social attitudes and political trust are significant and meaningful but how strong are they? How are we to interpret the ‘path coefficient’ values in this diagram? Well, if there is a path coefficient of 0.20 between g (at age 11) and degree of liberal attitudes at age 33, this means that if g increases by 1 standard deviation from its mean (e.g. around 15 points on a typical IQ test, from 100 to 115), then the ‘liberal social attitude’ measure would be expected to increase by 1/5 of a standard deviation from its own mean (the assumed population mean for ‘liberal social attitudes’) – holding all the other coefficients in the model constant. If liberal social attitudes were measured like a psychometric IQ test, an IQ level of 115 in the population of 11 year olds, would predict (i.e. be causally instrumental in) a liberal attitude score of 103 in the population  at 33 years of age –  3 points above the population mean for liberalism.

So as far as I can see these causal links are not that strong! Nothing like the relationship between IQ and educational attainment (in qualifications) for instance – with a path coefficient of around 0.5. There are many other factors that have an impact on liberal social attitudes other than IQ level. But it DOES have a causal role. IQ does tend to make people more liberal (and to a lesser extent less prone to conspiracy theories or cynicism about the political system).

Here is my  model of explicit motivation (as opposed to implicit, introspectively inaccessible motivation), executive processes and fluid and crystallized intelligence. Lots of reviewing of the literature and experiments to do now!

In the New York Times article on this paper (link), the author points out that

Brain-imaging studies of people evaluating anomalies, or working out unsettling dilemmas, show that activity in an area called the anterior cingulate cortex spikes significantly. The more activation is recorded, the greater the motivation or ability to seek and correct errors in the real world, a recent study suggests. “The idea that we may be able to increase that motivation,” said Dr. Inzlicht, a co-author, “is very much worth investigating.”

This is one of those extraordinary ‘connection’ moments for me. This idea relates precisely to the implicit and explicit motivation dual process account I just wrote up in a book chapter. In Dr Inzlicht’s paper, the magnitude of the ‘Error Related Negativity’ ERP component (generated by the anterior cingulate cortex) following errors was significantly correlated with better academic performance as measured by official student transcripts. So here we have a  link between ‘norm violation’ detection and intelligence. Interestingly Dr. Inzlicht seems to understand the effect in terms of motivation: the motivation to correct errors. More on this later.

How might this Anterior Cingulate study relate to Proulx & Heine ’Kafka’ study?  Here is a quote from the paper on meaning compensation:

Several recent studies have suggested that people will also fluidly compensate for meaning threats by affirming unrelated meaning frameworks (e.g., Burris & Rempel, 2004; McGregor et al., 2001; Navarrete, Kurzban, Fessler, & Kirkpatrick, 2004). In response to these studies, we have directly tested and supported the hypothesis that the meaning frameworks people affirm in meaning-maintenance efforts are radically substitutable, such that one meaning framework (e.g., moral beliefs) or another meaning framework (e.g., group affiliation) may be called upon when an unrelated meaning framework (e.g., a perceptual schema) is violated (Proulx & Heine, 2008).

My proposal is that this ‘radical substitutability’ may reflect an underlying normativity learning & self regulating system, that relates to intelligence. When there are threats to meaning (i.e. normativity), this system has a widespread motivational effect on all normatively regulated cognition from perception and grammar all the way up to moral and existential value-systems.