How Modular Is Intelligence?
unz.com
unz.com
There is only one study cited here showing negative correlation between any two aspects of intelligence, despite this being worthy of study for the whole of a century. That shouldn't even register as random noise.
We do know that the brain itself is quite modular, with various areas of the brain having specific functions. I had a rather disturbing experience that vividly illustrated just how specialised the function of different brain region is. It statrted with a short episode of hemianopia, which was a really bizzare experience in itself - I lost the ability to see the right half of my normal vision. In both eyes. Then, after normal vision returned, I noticed that when looking at text I could make out individual letters, I could see the words as a collection of letters, but I could not put the letters together and understand any of the words.
I had a pile of tests afterwards, including a brain CAT scan, that fortunately found nothing terribly wrong, and the episode was diagnosed as a vascular spasm. But apparently the brief interruption of blood flow to some particular region of the brain had interfered with the "module" that made words out of letters, while leaving other brain functions unaffected.
I have since then formed a belief that our minds are assembled from numerous modules, rather than being a monolithic whole.
It is correct that Charles Spearman originated the current, generally accepted view of "general intelligence" (g) as a common factor for diverse mental abilities tapped by a variety of mental tests. Each kind of mental test, in Spearman's view, also tapped "special abilities" (s) and Spearman, contrary to the brief account here, elaborated his view of those in the years after his landmark 1904 publication on general intelligence. Spearman wrote, in a 1927 writing I'm indebted to John Raven for drawing to my attention, "Every normal man, woman, and child is, then, a genius at something as well as an idiot at something. It remains to discover what—at any rate in respect of the genius."[1]
The article continues, "In recent years, however, we’ve begun to identify the actual genes that contribute to intelligence. These genes are very numerous, numbering perhaps in the thousands, with each one exerting only a small effect." The second sentence quoted here is a lot more accurate than the first. We know FOR SURE that genes that influence human intelligence number in the many hundreds, with confusing interactions with one another and with differing environmental conditions, and also know for sure that none of those genes have a large effect acting alone. But we have barely begun to identify any of the individual genes.
Blogger Peter Frost then comments on some current primary research publications. As someone who regularly discusses current research with other researchers in the local journal club,[2] I'm always glad to see citations to some new primary research studies, but I've also learned how few of those replicate, and how limited our precision is so far in matching behavior patterns to gene assemblages in Genome-Wide Association Studies (GWAS) in human subjects. The sample sizes are becoming more and more huge in human GWASs, but are still too small to provide reliable data on associations between genes and behaviors of interest.[3]
The unreplicated primary research studies he cites (in some cases from very obscure journals) will be worth following up on, but right now I think the blogger's suggested conclusions run ahead of the evidence, particularly about spread of literacy in some regions being associated with particular genes--the sample sizes of the relevant populations are still grossly inadequate for backing up conclusions like that.
P.S. Reliable information about the neurological underpinnings of reading ability can be found in the book Reading in the Brain,[4] by a scientist who has done many neuro-imaging studies of reading ability, a very readable and interesting book.
[1] http://assessingpsyche.wordpress.com/2014/01/14/strawman-spe...
[2] http://www.psych.umn.edu/research/areas/pib/
Even without the research, quantifying what counts as "general aptitude" and what doesn't is hard to do, and measuring whatever we decide to quantify is even harder. Here's to hoping that a more nuanced view of intelligences take off :)
Did anybody ever really think it was? Or is this just a strawman put up by people who are opposed to IQ rankings on either personal (waah, I didn't score that high) or political (waah, group X doesn't score very high on average) grounds?
The idea of general intelligence makes about as much sense as the idea of general physical fitness. That is, quite a bit. It's useless to ask whether [famous basketballer] is more or less fit than [famous footballer], but we can usefully answer the question of whether [famous footballer] is more or less fit than [random dude].
Similarly, if we're an organisation that wants to select people for physical fitness (like, say, the US marines) we could make up a test and a score (http://en.wikipedia.org/wiki/United_States_Marine_Corps_Phys...) which in some way quantify an individual's physical fitness with a numerical score. The tests used are somewhat arbitrary and the precise ordering you get on this scale is different to the ordering you'd get if you used a different though equally sensible set of tests, but this doesn't change the fact that "physical fitness" is a real thing and that this test is a reasonable way of quantifying it. All reasonable measures of general physical fitness will give highly correlated results.
2. As this article points out, almost half of the performance of the various subsystems does seem to have a common source. So getting rid of IQ/g completely wouldn't make sense.
Now, pointing out specifically which other factors are most relevant for specific tasks would be useful (especially for things that require reading emotions, since that's least correlated). Finding which factors are least correlated is useful (so you know what's most important to check tasks for).