The Many Meanings of Modules

• Modularity issue... or issues? by Eric Rietzschel, 11/7/98
  • How Many Angels Can Dance in Our Heads by James Brody, 11/10/98
    • 'Modularity' may be a misleading term by Eric Rietzschel, 11/10/98
      
      

I just dropped in on your postings, Eric, and I thought that I might add a comment. I think you are right; the multiple use of the term "module" in so many different contexts is unnecessarily confusing. I'm sure that whatever Fodor's modules may be, they are quite different from at least one fairly well defined example of the use of this term. Based on neurology, neuroanatomy and cognitive neuroscience (not to be confused with cognitive psychology), the word "module" is used to refer to fairly circumscribed regions of the cerebral cortex which seem to mediate certain fairly well defined functions. For example, if you see a bouncing, red rubber ball, neuroscientists know from a variety of types of evidence that the human brain processes the shape of the object (the ball) in one cortical region, the color is procesed in another and the movement in still a third area. Persons with brain damage to this last area, for instance, can see quite well until the ball moves, whereupon it appears to disappear! Language functions are similarly localized: language generation requires Broca's area while language comprehension requires the functioning of Wernicke's area, and in both cases, only in the left cerebral hemisphere. This type of structure-function relationship is the basis of using the term "module" to describe these cortical areas.

Cognitive neuroscientists, such as Michael Gazzaniga, use the term "module" similarly to refer to brain areas revealed by fNMR, PET scan, etc., to be associated with even more specific functions, such as decision making, processing nouns as opposed to verbs, recognizing natural objects (as opposed to natural objects, which are processed elsewhere) and so on. Again, with ample evidence of a structure-function connection, the use of the term "module" to refer to these areas seems well defined and useful.

Some neuroscientists, such as Gazzaniga and Bob Ornstein, also use the term to refer to specific operations or behaviors that are behaviorally quite evident but the anatomical localization is quite minimal, such as to the left frontal cortex (which is a lot of cortex). Examples are Gazzaniga's "Interpretor" module, which generates verbal explanations for behaviors generated by the right hemisphere but of which the language-using left hemisphere is unaware. Here the useage is more vague, since the localization is vague.

Anyway, this is a very brief and incomplete description of how brain researchers use the term module. Evolutionary psychologists also use the term, but here only the function is well defined (such as your example of phobias), while the structure(s) and processes by which they are mediated remain to be elucidated. Perhaps a modifier attached to module, such as evolved module, or behavioral module would clarify the distinction. As far as philosophers, linguists and others such as Jerry Fodor, I'm sure you have a better understanding of how they use the term than I do.

In short, I think that you are correct in your view that the nomenclature used by different types of thinkers differ in meaning and, therefore, different terms should be used to reduce unnecessary confusion. Keeping track of what different experts think is hard enough without them all using the same words to refer to quite different things.

BTW, I can provide references on the neuroscience if you are interested.

Mike

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