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 Message-ID: <19880918192114.7.NICK@HOWARD-JOHNSONS.LCS.MIT.EDU> Date: 18 Sep 88 19:21:00 GMT Sender: daemon@bloom-beacon.MIT.EDU Organization: The Internet Lines: 51 Approved: ailist@ai.ai.mit.edu 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)