Colom, R., Rebollo, I., Palacios, A., Juan-Espinosa, M., & Kyllonen, P.C. (2004). Working memory is (almost) perfectly predicted by g. Intelligence, 32(3), 277-296. doi:10.1016/j.intell.2003.12.002.
Andrew Sullivan, Ezra Klein, Half Sigma, and other bloggers of note are going around on the question of the heritability of intelligence in general, and the possibility of biological causes for the differences in general intelligence obsered in different groups. While occasionally people speak carelessly, it’s remarkable how far the Standard Social Sciences Model (SSSM) of all human differences being the result of different environments has already collapsed. There are three traditional ways to attack the notion in biologically-driven racial differences in general intelligence
- There is no such thing as general intelligence
- There are no such things are races
- The environmental conditions in which the races tend to exist are unequal
The first two criticism are discredited. One can deny g or ancestry in the same way that one can deny darwinian selection or the old Earth: through determined dogmatism.
The third criticism remains, if only because of the horrifying inequalities in the world today. Of course, environmental inequalities can rapidly turn into biological inequalities. One only needs to look at the Inbred Gap to know that. Yet it’s also true that one can be trained to perform better on any subset of tests that are used to measure general intelligence. Thus the Flynn Effect: this or that measure will suddenly deviate from the rest, causing illusionary growth or shrinkage in differences.
One measure that very closely approximates g (“(almost) perfectly predicts,” in the word of the paper’s excited authors) is working memory.
This article analyzes if working memory (WM) is especially important to understand g. WM comprises the functions of focusing attention, conscious rehearsal, and transformation and mental manipulation of information, while g reflects the component variance that is common to all tests of ability. The centrality of WM in individual differences in information processing leads to some cognitive theorists to equate it with g. There are several studies relating WM with psychometric abilities like reasoning, fluid intelligence, spatial visualization, spatial relations, or perceptual speed, but there are very few studies relating WM with g, defined by several diverse tests. In three studies, we assessed crystallised intelligence (Gc), spatial ability (Gv), fluid intelligence (Gf), and psychometric speed (Gs) using various tests from the psychometric literature. Moreover, we assessed WM and processing speed (PS). WM tasks involve storage requirements, plus concurrent processing. PS tasks measure the speed by which the participants take a quick decision about the identity of some stimuli; 594 participants were tested. Confirmatory factor analyses yielded consistently high estimates of the loading of g over WM (.96 on average). WM is the latent factor best predicted by g. It is proposed that this is so because the later has much in common with the main characteristic of the former.
Working memory allows you to make sense of information, so that you can remember it. It is most important in that it makes it easier to memorize things. This also explains why school appears to lower general intelligence of high-performing populations, such as Chinese: if you are in an environment where high academic achievement is socially punished, excess working memory capacity naturally atrophies. Similarly, this may explain why the heritability of g increases in life: once out of the socialized public schools, an individuals’ environment is more under his control, and an individual that enjoys tasks that involve the comprehension of complex materials will strengthen those neural connections more.
If g really is working memory, the educational implications are huge. The soft bigotry of low expectations is especially brutal to those apparently with low working memory capacity. Because working memory does not matter once a task is memorized. Memorization is the way-out of the trap of low working memory. And what’s needed for memorization is clear: practice, academic discipline, and practice. Yet who believes that fifty years after Brown v. Board of Education most majority-black schools are models of academic seriousness and discipline?
Even more tragic — if the link between general intelligence and working memory is strong — working memory is trivially easy to test. There’s no need for race-conscious policies at all to battle what may be the worst racial inequality through education. We could close much of the achievement gap, regardless of average biological differences between races.
Instead, we have America’s public schools.