
How Modular Is Intelligence? - 2a0c40
http://www.unz.com/pfrost/how-modular-is-intelligence/
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learnstats
Answer: Not at all. Science rarely has such unanimity on any topic as that
illustrated by this article.

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.

~~~
D_Alex
A strong negative correlation does not support the claim that intelligence is
modular (which I interpret as "made up of somewhat independent modules"), it
would in fact support the claim that a common factor is responsible for high
performance in one area and low performance in another.

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.

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tokenadult
The submission kindly made here is a controversial blog post by a blogger who
habitually blogs about topics that I actively research for my professional
research. First I read the previous comments here, then I read the fine blog
post by Peter Frost.

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...](http://assessingpsyche.wordpress.com/2014/01/14/strawman-spearman-vs-
charles-spearman/)

[2]
[http://www.psych.umn.edu/research/areas/pib/](http://www.psych.umn.edu/research/areas/pib/)

[3]
[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3778125/](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3778125/)

[4] [http://readinginthebrain.pagesperso-
orange.fr/intro.htm](http://readinginthebrain.pagesperso-orange.fr/intro.htm)

~~~
joshmarlow
Thanks for the thorough comment and links. While blogposts are often
interesting/thought-provoking, it's great to be able to read a response by a
professional.

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tbrownaw
So we have special circuitry for recognizing written words and letters, that
seems to be specialized from part of our facial-recognition circuitry? Very
cool. :)

~~~
jonsen
I've heard that learning to read is at the expense of facial recognition
ability.

~~~
listic
It would be really interesting to see that study. Could you possibly find it?

~~~
jonsen
[http://en.wikipedia.org/wiki/Neuronal_Recycling_Hypothesis](http://en.wikipedia.org/wiki/Neuronal_Recycling_Hypothesis)

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norseboar
I hope more research like this catches on in the mainstream to help dismantle
the idea of a fixed "IQ" altogether. While it's convenient to score people on
intelligence, and nice to believe there's a simple scalar ranking, there's a
growing body of research showing that it's just not the case.

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 :)

~~~
afafsd
>While it's convenient to score people on intelligence, and nice to believe
there's a simple scalar ranking, there's a growing body of research showing
that it's just not the case.

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...](http://en.wikipedia.org/wiki/United_States_Marine_Corps_Physical_Fitness_Test))
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.

