Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!F.GP.CS.CMU.EDU!Joseph.Tebelskis
From: Joseph.Tebelskis@F.GP.CS.CMU.EDU
Newsgroups: comp.ai.digest
Subject: Re: I got rhythm
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Date: 18 Sep 88 19:21:00 GMT
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To: AIList@AI.AI.MIT.EDU
Subject: Re: I got rhythm
Date: Fri, 16 Sep 88 03:07 EDT
From: Joseph.Tebelskis@F.GP.CS.CMU.EDU

In V8 #83, Phil Goetz asks:

> It comes down to this:  Different actions require different processing
> overhead.  So why, no matter what we do, do we perceive time as a constant?
> Why do we, in fact, have rhythm?  Do we have an internal clock, or a
> "main loop" which takes a constant time to run?  Or do we have an inadequate
> view of consciousness when we see it as a program?

First you need to realize that the computer is a poor metaphor for the brain.
Modern computers are organized around a single CPU through which all the
computations must flow, while memory plays a passive and underutilized 
role -- hence the CPU is called the "bottleneck" of modern computers.  
As you noted, multitasking slows down individual tasks on such machines.
In contrast, the brain has a hundred billion processors (neurons), and its
vast memory is active rather than passive.  Its various modules operate in
parallel, so they don't slow each other down; this is why we can perceive 
time as a constant no matter what we're doing.  Also, the brain does not 
execute a high-level "program" of instructions: its operation is guided by 
autonomous physical processes at the neural level.  From this neural level 
emerge all the diverse cognitive phenomena, including rational thought, 
emotions, and consciousness.  However, the only emergent phenomenon which 
maps well onto our computer programming paradigm is rational thought -- so
that's what symbolic AI has always concentrated on.  The emergent phenomenon 
of consciousness is "made of the same stuff" at a low level, but it just
cannot be approximated satisfactorily at the symbolic (programming) level.

With regard to rhythm and parallelism, I currently visualize the brain 
as an extremely complex "resonance chamber".  At various scales and 
physical locations within the brain, different subnetworks can be resonating 
in different ways.  The simplest kind of resonance would be a cyclical 
reverberation of activity at a characteristic frequency; such a pulsing
signal could control your foot as you tap out a rhythm.  More complex types 
of resonance may simultaneously be in operation elsewhere in the brain, 
controlling unrelated cognitive tasks such as doing a math problem.  I 
suspect that subnetworks of the brain use complex resonance patterns to 
symbolically represent brief progressions of events, such as perceptual 
sequences, fast motor procedures, and internal state transitions.  Such 
temporally encoded symbols, recursively telescoped together in the 
"resonance chamber" of the brain, may account for the natural emergence of
a hierarchy of symbolic representations for event progressions spanning 
arbitrary time scales.  It is also conceivable that resonant representations 
avoid interfering with each other in the brain just as physical waves do, 
by superposition.  

  Joe Tebelskis, connectionist
  (jmt@f.gp.cs.cmu.edu)