Re: Is the brain a serial processor?

Robert J. Bradbury (
Thu, 9 Sep 1999 21:38:41 -0700 (PDT)

On Fri, 10 Sep 1999, Patrick Wilken wrote:

> By R. Colin Johnson EE Times (09/08/99, 10:48 a.m. EDT)

> For such diverse tasks it is clear that the brain does operate in
> parallel. But when it comes to tasks involving similar data items, the
> brain appears to time-division multiplex, that is, focus its attention
> on one object at a time so quickly that the conscious mind is not aware
> of it.

Oh, oh, I think this is Eliezer's, "unconscious congnition" raising its ugly head.

[!!!DANGER EXTROPIANS DANGER!!! BAD MEME ALERT] [Said in the voice of the Lost in Space Robot]

> "It's counterintuitive because it seems to our conscious mind
> that we are comparing objects simultaneously, but we now think that the
> brain's parallelism is similar to a computer's-that is, a computer has
> millions upon millions of simultaneously acting transistors, but at the
> functional level it is operating serially-one instruction at a time,"
> Luck said.

[more snip]

Sigh! This is what happens when you let a wet-matter biologist comment on computer architectures. Luck's concept of computer architectures died 5-10 years ago.

No discussion of Symmetric Multiprocessors (SMP) that have simultaneous access to memory! No discussion of processors with multiple "execution units" doing instructions simultaneously! No discussion of SIMD (Single Instruction Multiple Data) or MIMD (Multiple Instruction Multiple Data) architectures processing data streams simultaneously! No discussion of architectures like the TERA that simultaneously stream dozens of data elements in and out of memory and can do a context switch on each instruction to operate on the data that happens to be available.

Good thing his email address isn't included. Hrummphhh!

Most importantly, all this work says is that there is serial consideration of items in the visual field as subjects for limited analysis operation. It would seem to be the analysis operation (something that requires a yes/no decision by the conscious mind) that is the hurdle. Unfortunately, it only pays lip service to a few of the many things the brain *can* do simultaneously.