non-commutativity in the brain

Scott Martens smartens at
Wed Apr 5 10:36:45 PDT 2000

Yoshi wrote:

> Interesting. What is called "consciousness" must be a tiny part of the
> total neuron firings. Much of information gets effectively & efficiently
> processed by our brains without it ever entering into "consciousness." To
> me, this fact militates against the Chomsky thesis that "deep" grammar is
> innate (from which Steven Pinker took off into a fundamentalist
> adaptationist direction) and favors the Gould-Lewontin anti-adaptationist
> argument that language may well be an accidental by-product of big brains.
> What feels "innate" is what is learned effortlessly without an awareness of
> being taught.

Actually, Chomsky takes Gould and Lewontin's side against Pinker. He thinks "universal grammar" is a biproduct of something else and that looking for adaptionist explanations is a waste of time. I disagree.

> Evolutionary psychologists like Steven Pinker are committed to the idea of
> "modularity." They argue that:

> ***** Human behavior and mental operations can be divided into a
> relatively discrete set of items, or mental organs. (In one prominent
> study, for example, authors designate a "cheater detector" as a mental
> organ, since the ability to discern infidelity and other forms of
> prevarication can be so vital to Darwinian success-the adaptationist
> rationale.) The argument for modularity flows, in part, from exciting work
> in neurobiology and cognitive science on localization of function within
> the brain-as shown, for example, in the precise mapping, to different areas
> of the cerebral cortex, of mental operations formerly regarded as only
> arbitrarily divisible by social convention (production of vowels and
> consonants, for example, or the naming of animals and tools).

I agree with much of the programme of the evolutionary psychologists, but I don't think Pinker's modularity is likely to be true.

There is an intermediate position which I think better explains the data. It is clear that some brain activities take place in highly specialised parts of the brian and processes evolved specifically for that purpose. Vision, for example, is largely localisable and exists to some extent apart from other cognitive processes. Having evolved for billions of years, it is hardly surprising that a very efficient and specialised vision processing organ should exist.

The case for language is less clear. I still have never seen a reasonable challenge to Chomsky's poverty of stimulus argument, so I do think language has to be biologically motivated. However, I think the pre-adaptionists - most of whom are sympathetic if not openly supportive of evolutionary psychology - have a better case than either Pinker or Chomsky. They think that human language, and perhaps other human cognitive processes, are a result of retasking some kind of brain functionality evolved for some other purpose. The candidate most often cited is throwing, which as an abstract problem is not entirely dissimilar to the problem of language.

Rather, I think the best case against Pinkerite modularity is the existence of sign languages and literacy. If human language had evolved exclusively for the purpose of speaking, as vision processing has clearly evolved for the purpose of seeing, we ought not to have sign languages at all, and children shouldn't be able to learn them in the same way that they learn spoken language (which they clearly do.) Furthermore, most adults can read faster than they can speak. It seems clear that in reading we do not use the auditory signal processing parts of the brain.

If language had evolved for speaking, we ought to see it much more closely bound to speech and hearing. Instead, we can easily hijack our "language module" for sign languages and processing visual symbols. We can't do anything comparable with the brain functions that we use to see.

> Ironically, though, neurobiology and evolutionary psychology employ the
> concept of modularity for opposite theoretical purposes. Neurobiologists do
> so to stress the complexity of an integrated organ. Evolutionary psychology
> uses modularity to atomize behavior into a priori, subjectively defined,
> and poorly separated items (not known modules empirically demonstrated by
> neurological study), so that selective value and adaptive significance can
> be postulated for individual items, as the ultra-Darwinian approach
> requires. (Stephen Jay Gould, "Evolution: The Pleasures of Pluralism,"
> _NYRB_ 26 June 1997) *****

> The difference between nuerobiology and evolutionary psychology that Gould
> notes -- especially in how the concept of modularity gets employed in each
> program -- seems important to me.

I'm suspicious of Gould. I think he would just like to deny that Darwinism has anything to do with the brain, and his anti-adaptionist programme is fairly unconvincing.

However, the point that neurobiologists are much more hesitant to posit "brain modules" than Pinker is holds true in my experience. I do think there is a middle ground that is much more likely.

When I do genetic programming, there are sometimes things that are functionally similiar to "brain modules" that appear. However, most often there are a small number of modules that get used and reused in a variety of ways. There are components that the system can be reduced to, but often, it's the same component with only small differences in many places. So, I suspect the brain is both more and less modular that Pinker thinks. I suspect much of the activity of the brain can be explained with a small number of non-distinct modules assembled in somewhat different ways.

I don't think the evidence is there for the kind of strict modularity some of the evolutionary psychologists predict. I do think that there is some merit to their case and programme, but that my case is better.

Scott Martens


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