Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!seismo!columbia!rutgers!princeton!mind!harnad From: harnad@mind.UUCP (Stevan Harnad) Newsgroups: comp.ai,comp.cog-eng Subject: Re: The symbol grounding problem Message-ID: <950@mind.UUCP> Date: Wed, 1-Jul-87 00:59:22 EDT Article-I.D.: mind.950 Posted: Wed Jul 1 00:59:22 1987 Date-Received: Thu, 2-Jul-87 01:36:54 EDT References: <764@mind.UUCP> <768@mind.UUCP> <770@mind.UUCP> <6174@diamond.BBN.COM> <1200@houdi.UUCP> Organization: Cognitive Science, Princeton University Lines: 97 Summary: How we name things correctly must be inferred, not introspected Xref: mnetor comp.ai:596 comp.cog-eng:167 marty1@houdi.UUCP (M.BRILLIANT) of AT&T Bell Laboratories, Holmdel writes: > how long do you imagine the Total Turing Test will last?... By > "performance capabilities," do you mean the capability to adapt as a > human does to the experiences of a lifetime? My Total Turing Test (TTT) has two components, one a formal, empirical one, another an informal, intuitive one. The formal test requires that a candidate display all of our generic performance capacities -- the ability to discriminate, manipulate, identify and describe objects and events as we do, under the same conditions we do, and to generate and respond to descriptions (language) as we do. The informal test requires that the candidate do this in a way that is indistinguishable to human beings from the way human beings do it. The informal component of the TTT is open-ended -- there is no formal constraint on how much is enough. The reason is that I proposed the TTT to match what we do in the real world anyway, in our informal everyday provisional "solutions" to the "other-minds" problem in dealing with one another. Robots should be held to no more or less exacting standards. (This was extensively discussed on the Net last year.) > We've found a set of lines, described in 3 dimensions, that can be > rotated to match the outline we derived from the view of a real chair. > We file it in association with the name "chair." A "similar form" is > some other outline that can be matched (to within some fraction of its > size) by rotating the same 3D description. I agree that that kind of process gets you similarity (and similarity gradients), but it doesn't get you categorization. It sounds as if you're trying to get successful identification using icons. That will only work if the inputs you have to sort are low in confusability or are separated by natural gaps in their variation. As soon as the sorting problem becomes hard, feature-learning becomes a crucial, active process -- not one that anyone really has a handle on yet. Do you really think your stereognostic icons of chairs will be able, like us, to reliably pick out all the chairs from the nonchairs with which they might be confused, using only the kinds of resources you describe here? > Is [categorization] the process of picking discrete objects out of a > pattern of light and shade ("that's a thing"), or the process of naming > the object ("that thing is a chair")? The latter. And reliably saying which confusable things are chairs vs. nonchairs as we do is no mean feat. > I think I find objects with no conscious knowledge of how I do it (is > that what you call "categorization")? Saying what kind of object it is > more often involves conscious symbol-processing Categorization is saying what kind of object it is. And, especially in the case of concrete sensory categories, one is no more conscious of "how" one does this than in resolving figure and ground. And even when we are conscious of *something*, it's not clear that's really how we're doing what we're doing. If it were, we could do cognitive modeling by introspection. (This is one of the reasons I criticize the Rosch/Wittgenstein line on "necessary/sufficient" features: It relies too much on what we can and can't introspect.) Finally, conscious "symbol-processing" and unconscious "symbol-processing" are not necessarily the same thing. Performance modeling is more concerned with the latter, which must be inferred rather than introspected. > I agree that [finding objects in a field of light and shade] > is done nonsymbolically... [but] Calling a penguin a bird seems to me > purely symbolic, just as calling a tomato a vegetable in one context, > and a fruit in another, is a symbolic process. Underlying processes must be inferred. They can't just be read off the performance, or our introspections about how we accomplish it. I am hypothesizing that higher-order categories are grounded bottom-up in lower-order sensory ones, and that the latter are represented nonsymbolically. We're talking about the underlying basis of successful, reliable, correct naming here. We can't simply take it as given. (And what we call an object in one context versus another depends precisely on the sample of confusable alternatives that I've kept stressing.) > If [cognition/categorization] begins nonsymbolically, and proceeds > symbolically, why can't it be done by linking a nonsymbolic module to > a symbolic module? Because (according to my model) the elementary symbols out of which all the rest are composed are really the names of sensory categories whose representations -- the structures and processes that pick them out and reliably identify them -- are nonsymbolic. I do not see this intimate interrelationship -- between names and, on the one hand, the nonsymbolic representations that pick out the objects they refer to and, on the other hand, the higher-level symbolic descriptions into which they enter -- as being perspicuously described as a link between a pair of autonomous nonsymbolic and symbolic modules. The relationship is bottom-up and hybrid through and through, with the symbolic component derivative from, inextricably interdigitated with, and parasitic on the nonsymbolic. -- Stevan Harnad (609) - 921 7771 {bellcore, psuvax1, seismo, rutgers, packard} !princeton!mind!harnad harnad%mind@princeton.csnet harnad@mind.Princeton.EDU