10 October 2016

Of Oliver Sacks, Gerald Edelman, perception, terminology and more #1

I've just finished reading On the move by Oliver Sacks.


The second last chapter is entitled A new vision of the mind.

On p363 of the UK edition we have (with my punctuation):
Where perception of objects is concerned, Edelman* likes to say, the world is not "labeled"; it does not come "already parsed into objects". We must make our perceptions through our own categorizations. "Every perception is an act of creation," as Edelman says. As we move about, our sense organs take samplings of the world, and from these, maps are created in the brain. There then occurs with experience a selective strengthening of those mappings that correspond to successful perceptions  successful in that they prove the most useful and powerful for the building of "reality".
Edelman speaks here of a further, integrative activity peculiar to more complex nervous systems, this he calls "reentrant signaling". In his terms, the perception of a chair, for example, depends first on the synchronization of activated neuronal groups to form a "map", then a further synchronization of a number of scattered mappings throughout the visual cortex -- mappings related to many different perceptual aspects of the chair ( its size, its shape, its color, its "leggedness", its relation to other sorts of chairs  armchairs, rocking chairs, baby chairs, etc.). In this way, a rich and flexible percept of "chairhood" is achieved, which allows the instant recognition of innumerable sorts of chairs as chairs. This perceptual generalization is dynamic, so it can be continually updated, and it depends on the active and incessant orchestration of countless details.
Such correlations and synchronization of neuronal firing in widely separated areas of the brain is made possible by very rich connections between the brains maps  connections which are reciprocal and may contain millions of fibers. Stimuli from, say, touching a chair may affect one set of maps, stimuli from seeing it may affect another set. Reentrant signaling takes place between these set of maps as part of the process of perceiving a chair.
Categorization is the central task of the brain, and reentrant signaling allows the brain to categorize its own categorizations, then recategorize these, and so on. Such a process is the beginning of an enormous upward path enabling ever higher levels of thought and consciousness.
*: Gerald M Edelman, author of Neural Darwinism (1987) 

Many who have read about the origins or the philosophy of terminology will have realised that the decision to focus on the perception of a chair rather than, say, a table or anything else is no accident. It has been used by others including Steven Pinker in Words and Rules (p273 of the Perennial paperback edition), though I'm not sure who used it first. In any case, as Pinker says, this superb cartoon from The New Yorker "says it all".

"Attention, everyone! I'd like to introduce the newest member of our family."
The New Yorker Collection 1977 Jeff Kaufman from cartoonbank.com. All rights reserved.

The initial insights in this area appeared in Philosophical Investigations (German: Philosophische Untersuchungen), where Ludwig Wittgenstein uses the word 'Spiele' as his example.

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