Massive parallel processing

On the ConsciousEntities site, there is a discussion of some of Dennett’s ideas (here). Near the end of the post there is a paragraph about parallel processing that I find misleading.

Unfortunately Dennett repeats here a different error which I think he would do well to correct; the idea that the brain does massively parallel processing. This is only true, as I’ve said before, if by ‘parallel processing’ you mean something completely different to what it normally means in computing. Parallel processing in computers involves careful management of processes which are kept discrete, whereas the brain provides processes with complex and promiscuous linkages. The distinction between parallel and serial processing, moreover, just isn’t that interesting at a deep theoretical level; parallel processing just a handy technique for getting the same processes done a bit sooner; it’s not something that could tell us anything about the nature of consciousness.

First, the brain does massive parallel processing and I cannot think of a better way of saying it. It is ‘massive’; it is ‘parallel’; and it is ‘processing’. And yes, it is not the same as the way computers do parallel processing, but then the computer metaphor (brain=computer; cognition=computation; process=algorithm) is only a so-so metaphor. The brain is much more like an analog computer then a digital one and even that metaphor is still somewhat stretched. Parallel processing in the computer world is just a bunch of serial operations being done at the same time. That is not what the brain is doing when it does ‘massive parallel processing’.

The brain may have promiscuous linkages but no one has yet shown either that they exist or that they don’t. What would a promiscuous linkage look like? Unless you believe that all processes are basically serial algorithms (which I don’t) then there is a theoretical interest in whether a process is parallel, an interest beyond just being faster. Finally, the nature of consciousness is bound up in the thalamocortical system and that system is built of PARALLEL feedback loops, massively so. Get with the biology.

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