Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!watmath!clyde!rutgers!lll-lcc!well!wcalvin From: wcalvin@well.UUCP Newsgroups: comp.ai,comp.cog-eng Subject: Re: More on Minsky on Mind(s) Message-ID: <2556@well.UUCP> Date: Mon, 9-Feb-87 01:14:48 EST Article-I.D.: well.2556 Posted: Mon Feb 9 01:14:48 1987 Date-Received: Tue, 10-Feb-87 02:26:09 EST References: <460@mind.UUCP> <1032@cuuxb.UUCP> <465@mind.UUCP> Reply-To: wcalvin@well.UUCP (William Calvin) Organization: Whole Earth 'Lectronic Link, Sausalito, CA Lines: 141 Keywords: Consciousness, throwing, command buffer, evolution, foresight Summary: A "mechanical equivalent of consciousness" from movement planning? Xref: watmath comp.ai:213 comp.cog-eng:55 In following the replies to Minsky's excerpts from SOCIETY OF MIND, I am struck by all the attempts to use slippery word-logic. If that's all one has to use, then one suffers with word-logic until something better comes along. But there are some mechanistic concepts from both neurobiology and evolutionary biology which I find quite helpful in thinking about consciousness -- or at least one major aspect of it, namely what the writer Peter Brooks described in READING FOR THE PLOT (1985) as follows: "Our lives are ceaselessly intertwined with narrative, with the stories that we tell and hear told, those we dream or imagine or would like to tell, all of which are reworked in that story of our own lives that we narrate to ourselves in an episodic, sometimes semiconscious, but virtually uninterrupted monologue. We live immersed in narrative, recounting and reassessing the meaning of our past actions, anticipating the outcome of our future projects, situating ourselves at the intersection of several stories not yet completed." Note the emphasis on both past and future, rather than the perceiving- the-present and recalling-the-recent-past, e.g., Minsky: > although people usually assume that consciousness is knowing > what is happening in the minds, right at the > present time, consciousness never is really concerned with the > present, but with how we think about the records of our recent > thoughts... how thinking about our short term memories changes them! But simulation is more the issue, e.g., E.O. Wilson in ON HUMAN NATURE 1978: "Since the mind recreates reality from abstractions of sense impressions, it can equally well simulate reality by recall and fantasy. The brain invents stories and runs imagined and remembered events back and forth through time." Rehearsing movements may be the key to appreciating the brain mechanisms, if I may quote myself (THE RIVER THAT FLOWS UPHILL: A JOURNEY FROM THE BIG BANG TO THE BIG BRAIN, 1986): "We have an ability to run through a motion with our muscles detached from the circuit, then run through it again for real, the muscles actually carrying out the commands. We can let our simulation run through the past and future, trying different scenarios and judging which is most advantageous -- it allows us to respond in advance to probable future environments, to imagine an accidental rockfall loosened by a climber above us and to therefore stay out of his fall line." Though how we acquired this foresight is a bit of a mystery. Never mind for a moment all those "surely it's useful" arguments which, using compound interest reasoning, can justify anything (given enough evolutionary time for compounding). As Jacob Bronowski noted in THE ORIGINS OF KNOWLEDGE AND IMAGINATION 1967, foresight hasn't been widespread: "[Man's] unique ability to imagine, to make plans... are generally included in the catchall phrase "free will." What we really mean by free will, of course, is the visualizing of alternatives and making a choice between them. In my view, which not everyone shares, the central problem of human consciousness depends on this ability to imagine..... Foresight is so obviously of great evolutionary advantage that one would say, `Why haven't all animals used it and come up with it?' But the fact is that obviously it is a very strange accident. And I guess as human beings we must all pray that it will not strike any other species." So if other animals have not evolved very much of our fussing-about-the- future consciousness via its usefulness, what other avenues are there for evolution? A major one, noted by Darwin himself but forgotten by almost everyone else, is conversion ("functional change in anatomical continuity"), new functions from old structures. Thus one looks at brain circuitry for some aspects of the problem -- such as planning movements -- and sees if a secondary use can be made of it to yield other aspects of consciousness -- such as spinning scenarios about past and future. And how do we generate a detailed PLAN A and PLAN B, and then compare them? First we recognize that detailed plans are rarely needed: many elaborate movements can get along fine on just a general goal and feedback corrections, as when I pick up my cup of coffee and move it to my lips. But feedback has a loop time (nerve conduction time, plus decision-making, often adds up to several hundred milliseconds of reaction time). This means the feedback arrives too late to do any good in the case of certain rapid movements (saccadic eye flicks, hammering, throwing, swinging a golf club). Animals who utilize such "ballistic movements" (as we call them in motor systems neurophysiology) simply have to evolve a serial command buffer: plan at leisure (as when we "get set" to throw) but then pump out that whole detailed sequence of muscle commands without feedback. And get it right the first time. Since it goes out on a series of channels (all those muscles of arm and hand), it is something like planning a whole fireworks display finale (carefully coordinated ignitions from a series of launch platforms with different inherent delays, etc.). But once a species has such a serial command buffer, it may be useful for all sorts of things besides the actions which were originally under natural selection during evolution (throwing for hunting is my favorite shaper-upper --see J.Theor.Biol. 104:121-135,1983 -- but word-order-coded language is conceivably another way of selecting for a serial command buffer). Besides rehearsing slow movements better with the new-fangled ballistic movement sequencer, perhaps one could also string together other concepts-images-schemata with the same neural machinery: spin a scenario? The other contribution from evolutionary biology is the notion that one can randomly generate a whole family of such strings and then select amongst them (imagine a railroad marshalling yard, a whole series of possible trains being randomly assembled). Each train is graded against memory for reasonableness -- Does it have an engine at one end and a caboose at the other? -- before one is let loose on the main line. "Best" is surely a value judgment determined by memories of the fate of similar sequences in the past, and one presumes a series of selection steps that shape up candidates into increasingly more realistic sequences, just as many generations of evolution have shaped up increasingly more sophisticated species. To quote an abstract of mine called "Designing Darwin Machines": This selection of stochastic sequences is more analogous to the ways of Darwinian evolutionary biology than to von Neumann machines. One might call it a Darwin machine instead, but operating on a time scale of milliseconds rather than millennia, using innocuous virtual environments rather than noxious real-time ones. Is this what Darwin's "bulldog," Thomas Henry Huxley, would have agreed was the "mechanical equivalent of consciousness" which Huxley thought possible, almost a century ago? It would certainly be fitting. We do not yet know how much of our mental life such stochastic sequencers might explain. But I tend to think that this approach using mechanical analogies from motor systems neurophysiology and evolutionary biology might have something to recommend it, in contrast to word-logic attempts to describe consciousness. At least it provides a different place to start, hopefully less slippery than variants on the little person inside the head with all their infinite regress. William H. Calvin Biology Program NJ-15 University of Washington Seattle WA 98195 USA 206/328-1192 USENET: wcalvin@well.uucp