March 30, 2007

A. R. Luria: The Neuropsychology of Praxis

Today's find, via Mind Hacks, is an online archive at UCSD dedicated to the memory of the great Soviet neuropsychologist Alexander R. Luria. (Lots of the links are broken, though.)

Today Luria's probably best known for the "neurographies" he wrote, like The Mind of a Mnemonist and The Man with a Shattered World, which inspired Oliver Sacks's famous ventures in this line. But he actually made really important scientific contributions, which deserve to be remembered.

Luria began his career as a disciple of Lev Vygotsky, who had a fascinating pre-cognitive theory of how individuals acquire higher mental functions through a scaffolding provided by cultural traditions (especially language) and social interaction. Vygotskyism was an explicitly Marxist theory: it was supposed to be a scientific account of how thought arises from practice. While it is very hard to accept some of Vygotsky's more extreme statements, there is I think a core of very real insight here, about both individual development and collective cognition, and one which moreover is fundamentally compatible with sound computational views of the mind.

To support the theory, Luria led an expedition to Uzbekistan which sought to document how the Soviet introduction of modern education and collective agriculture (!) was transforming the mentality of the natives. The resulting report — translated as Cognitive Development: Its Cultural and Social Foundations — is an astonishing mixture of fascinating experiments and conjectures, and equally fascinating displays of colonialist blindness. Most of Luria's subjects were Uzbekistani peasants who'd been forced onto collective farms a few years earlier; a decade previously the whole province was the scene of the basmachi revolt, which was suppressed by the Red Army with the usual measures. It never crossed Luria's mind, so far as I can tell, that a bunch of Russian academics, asking questions which clearly indicated that the Russians thought the Uzbeks were idiots, would meet with anything less than full and sincere cooperation. Consider the following dialogue (p. 112) with an illiterate peasant named Nazir-Said:

The following syllogism is presented: There are no camels in Germany. The city of B. is in Germany. Are there camels there or not?
Subject repeats syllogism exactly.
So, are there camels in Germany?
"I don't know, I've never seen German villages."
Refusal to infer.
The syllogism is repeated.
"Probably there are camels there."
Repeat what I said.
"There are no camels in Germany, are there camels in B. or not? So probably there are. If it's a large city, there should be camels there."
Syllogism breaks down, inference drawn apart from its conditions.
But what do my words suggest?
"Probably there are. Since there are large cities, there should be camels."
Again a conclusion apart from the syllogism.
But if there aren't any in all of Germany?
"If it's a large city, there will be Kazakhs or Kirghiz there."
But I'm saying that there are no camels in Germany, and this city is in Germany.
"If this village is in a large city, there is probably no room for camels."
Luria's interpretation was that Nazir-Said had difficulty with hypothetical syllogistic reasoning, as opposed to more concrete inferences in practical situations, difficulties typical of those "whose cognitive activity was formed by experience and not by systematic instruction or more complex forms of communication" (p. 115). But it's also easy to interpret this as Nazir-Said parrying the question with a perfectly valid, if enthymemic, syllogism (as it were: "Every large city has camels; B. is a large city; therefore B. has camels"), and then supporting his major premise with another valid syllogism (like: "Every large city has Kazakhs or Kirghiz; Kazakhs and Kirghiz always have camels; therefore every large city has camels"). The greater success of members of collective farms in "solving" the syllogisms might just reflect their greater willingness to cooperate with the Russians. In other words, there is a whole layer of issues here, involving the social relations between the scientists and their subjects, to which Luria turned a blind eye...

Even in Russian, this book wasn't published until 1974. One reason, to which Luria and his translators allude, was the political sensitivity of saying that Central Asians had a child-like mentality, even if that was being transformed by socialist labor. The other, though, on which they are conspicuously silent, was the well-known fact that a crude Pavlovian behaviorism became the Official Soviet Line in psychology. Vygotsky was in a sense lucky to die of tuberculosis then, rather than be purged, and Luria had to lie low in an institute for retarded children. (An old New York Review piece on Luria goes into some of the history.) Luria's memoirs, written in the 1970s, are, let us say, extremely tactful about this turn of events. His American discipline Michael Cole, in an epilogue to those memoirs, is rather more open these matters, and confesses to finding some of what Luria wrote when, as it were, he was compelled to speak Pavlovian "unnerving". What I find unnerving is that none of this seems to have turned him against the Soviet system.

In any case, this forced switch in research ultimately led Luria, during and after the war, to rehabilitation work with soldiers with brain injuries, and so to neuropsychology, where he made his greatest contributions. His academic works from this period, like The Working Brain, present a picture of how cognition can work through what we would now call parallel, distributed processing, in which small brain regions perform specialized processing tasks, but none of the "higher cortical functions" maps directly, as it were phrenologically, onto a particular cortical area, but rather recruits these areas in shifting configurations. In particular, this would explain how lesions in single areas can lead to deficits in multiple functions, and conversely how there are many lesions which can cause a given functional deficit.

One could draw an analogy between this view of how the brain works and Marx's idea of how communism will overcome the division of labor. (This connection was never, so far as I know, even hinted at by Luria.) In a famous passage in The German Ideology, Marx and Engels write as follows:

[A]s soon as the distribution of labour comes into being, each man has a particular, exclusive sphere of activity, which is forced upon him and from which he cannot escape. He is a hunter, a fisherman, a herdsman, or a critical critic, and must remain so if he does not want to lose his means of livelihood; while in communist society, where nobody has one exclusive sphere of activity but each can become accomplished in any branch he wishes, society regulates the general production and thus makes it possible for me to do one thing today and another tomorrow, to hunt in the morning, fish in the afternoon, rear cattle in the evening, criticise after dinner, just as I have a mind, without ever becoming hunter, fisherman, herdsman or critic.
Analogously, according to Luria, a region in the frontal cortex (say) might be involved in grammatical parsing in the morning, the planning of rapid motion in the afternoon, and mental arithmetic in the evening, without ever being a parser, a planner or a calculator exclusively. I am tempted to turn this conceit into a just-so story about why Hayek and Hebb, in their accounts of distributed neural information processing, put so much less emphasis on functional flexibility, but I am afraid that someone might take me seriously. (For the record: Marx and Engels's ideas on overcoming the division of labor were profoundly utopian, and that is not a compliment.)

For what it's worth, I think Luria was really on to something here, and the fundamental point against a purely "phrenological" view of the brain is valid. There are times when I wish that no one would write a press release about a neuroimaging study without reading The Working Brain first. (The rest of the time, I wish no one would write press releases about neuroimaging at all.) But I also think it's really a matter of how much and in what manner. Part of the subtext of my own work on information in networks is to develop tools to make these questions quantitative ones, about estimation, rather than qualitative ones, about interpretation.

Which is a good note on which to do some calculations...

Manual trackback: Three Quarks Daily; Language Log; Uncommon Scolds [an interesting application which I need to think about more]

Minds, Brains, and Neurons; The Progressive Forces; Afghanistan and Central Asia; The Great Transformation; The Collective Use and Evolution of Concepts

Posted by crshalizi at March 30, 2007 15:20 | permanent link

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