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cs.Buffalo.EDU>ABSTRACTS OF PAPERS CONFERENCE ON COGNITION AND REPRESENTATION April 3-5, 1992 Center for Tomorrow, State University of New York at Buffalo FRIDAY AFTERNOON PAUL SMOLENSKY "Connectionism, Compositionality, and the Explanation of Productivity" The most fundamental fact that any theory of human cognition must explain is the incredible productivity of human knowledge. Most obviously in language, but also in other cognitive domains, human knowledge supports a range of appropriate behaviors that is appropriately idealized as infinite. The strategy for explaining this fact that has virtually defined cognitive science since its inception has been to (1) analyze the behaviors in question as possessing combinatorial structure, and (2) to identify human knowledge as part of an internal causal mechanism that physically realizes this combinatorial system. Possessing a finite repertoire of basic constituents and the means to (recursively) compose them, this mechanism explains productivity. Connectionism can respond to this in at least the following three ways: (1) Deny the problem. (2) Implement the standard explanation. (3) Offering a new explanation, possibly while revising the problem. Radical eliminativist connectionism takes option (1)--by default if not by explicit intent. Connectionist critics such as Fodor & Pylyshyn have advocated (2), and some connectionist research has also followed this option. In this talk, I will present results of my program of technical connectionist research based on option (3), and discuss its implications for the foundations of cognitive science. TIM VAN GELDER "Distributed Represenation--An Outline" What is distributed representation? This question is central to many practical and philosophical concerns, both in connectionism and in cognitive science more generally, yet it has never been given an answer that is both comprehensive and preceise. In this talk I propose a way of defining distribution that, on one hand, reveals the fundamental similarity between (for example) the gross functional neuroanatomy of the various brain areas and connectionist hidden unit activity patterns, while on the other is strict enough to yield mathematically precise descriptions in real modeling contexts. The key concept is that of semantic superimposition; I elaborate this suprisingly tricky concept, offer a formal framework rendering it precise, and explain how superimposition can be incorporated into a general definition of distributed representation. DAVID BANACH "Representing, Similarity, and the Storage of Information" Representing is an activity, a process through which a subject cognizes the world. Most theories of representation take one element or component of this activity and identify it as the representation by attributing to the element, in isolation, properties it has only in the context of the act of representing. In particular, I argue that the similarity of an icon to an object is neither necessary nor sufficient for representation and that seeing why this is so reveals fundamental defects with views that see representations as (1) stored information, which represents in virtue of an isomorphism effected by an information storage and retrieval algorithm; or (2) as a distributed pattern of activity over a set of units or phase space, which represents in virtue of a topological isomorphism to the represented object. All of these models identify the representation with some element of the cognitive process that cannot intrinsically represent apart from its situation in a wider context. I argue that such models of representation will fail to account for the cognitive role of representation as long as they mistake part of the representing process for the representating itself. ANN ROBYNS "Primary and Mature Conceptual Structures--Evidence from Child Language" Currently, in semanic enquiry some researchers represent lexical-conceptual structure as an architecture of sets and truth conditions. Others borrow from psychology such terms as 'conceptual primitives', 'canonical' and 'marginal' structures, and 'prototypes' (e.g. Jackendoff, 1990). The documentation of usage of verb argument structures, may shed considerable light on this division. Differentials in production of argument structures by children over time may shed light on the construction of underlying representations. These differences over time appear to also have an effect on complexity of context sentences. Production of tense, mood and negation markers appears to be contingent on the stability of conceptual structures underlying production of arguments. The current study supports the view that childrens' conceptual structures can be characterized as prototypes, and that gradual extension of structures is contingent on transition to new prototypes. Early on (1968), Fillmore advocated the need for distinct treatment of propositional and modal information. Our results show that the presence of modality in a sentence is contingent on high-frequency argument structures. If the development of modality (in Fillmore's sense) and propositional content are distinguishable but show this relation, how is it to be characterized? Jackendoff (1990) distinguishes between I-languages (internal, based on innate predispositions) and E-languages (input-dependent). He holds that truth-conditional semantics requires a theory of language as an abstract artifact extrinsic to speakers. A possible interpretation of our findings is that modality overlayed on propositional content may be the means whereby this abstract artifact is reconstructed as part of a speaker's internal representation. Truth-conditional semantics, then, involves modelling mature inferential processes, or mature representation. This possibility will be examined in light of actual developmental sequences, where modal forms can be shown to emerge gradually to condition verb meaning in ways at least reminiscent of model theoretic semantics. FRIDAY EVENING CHARLES FILLMORE "Representing Grammatical Knowledge as a Repertory of Constructions" (abstract not available) SATURDAY MORNING JOHN KOUNIOS and PHILLIPS HOLCOMB "Inferring Semantic-Memory Structure from Behavioral and Electrophysiological Measures" Researchers have investigated the structure of semantic-memory representations by examining subjects' performance in tasks in which they must judge the truth of sentences relating familar categories (e.g., _ALL DOGS ARE ANIMALS_., or _SOME PEOPLE ARE TREES_.). Differences in time to verify various classes of sentences were initally interpreted in terms of characteristics of the semantic representations retrieved from memory. Subsequent investigators have reinterpreted these findings in terms of characteristics of the verification _processes_ operating on these representations, rather than in terms of the representations themselves. We have taken a different approach. Instead of inferring the nature of knowledge representations based on how people _use_ them (i.e., "behavioral" response date), we have been investigating electrical protentials in the brain during sentence verification. A certain component of these potentials seems to reflect the _access_ or _retrieval_ of the stored knowledge, and not the processes that use this information to judge truth. These access/retrieval mechanisms better reflect structural characteristics of semantic memory than do behavioral measures, yielding a different picture of semantic-memory structure. VINOD GOEL "Specifying Classifying Representational Systems: A Critique and Proposal for Cognitive Science" Much of the work in cognitive science presupposes a theory of representation complete with a classification scheme; a scheme which allow us to say that two representations are interestingly similar or interestingly different for particular purposes. It is argued that such a scheme needs to meet at least the following eight constraints: (i) It must be grounded in some intuitions or a discipline-specific theory; (ii) It must not beg the crucial questions; (iii) It must result in an interesting number of categories (i.e., something other than a unit or infinite number); (iv) It must individuate on the basis of relevant/constitutive properties of symbol systems; (v) It must be readily applicable; (vi) It must be widely applicable; (vii) The distinctions must be detectable by our behavioral data and methodology; (viii) It must be compatible with the computational story of mind. The most widely used apparatus for classifying symbol systems is that of informational and computational equivalence. This is critiqued and found wanting on most accounts. A diagnosis of the problem is offered. Time permitting, some prescriptive suggestions will also be made. STEVEN HORST "Notions of Representation and the Diverging Interests of Philosophy and Empirical Science" Contemporary discussions of mental representation often seem to assume that there is a single sense of the word `representation' that (a) is applied univocally to such disparate objects as pictures, maps and symbols, (b) is utilized by empirical researchers in cognitive science, and (c) can readily be used to provide a philosophical account of intentionality. In fact, however, the notion of "representation" is paradigm-driven, and all of the familiar paradigms (symbols, etc.) are convention- or interpretation-dependent. This undercuts one philosophical strategy for explaining the content of mental states in representational terms. However, a non-conventional notion of "representation" as a theoretical term can be developed which seems to capture the empirical scientist's needs even if it does not explain the intentionality of mental states. This accords well with the following view of the importance of the computer paradigm: that what it provides is (i) a formalism for the mathematization of psychology and (ii) suggestive strategies for microexplanation. JERRY A. FODOR (and ERNEST LEPORE) "Representation, Compositionality, and Analyticity" We claim that three principles, all of which have been widely espoused in the philosophy of language and in cognitive science, cannot be simultaneously satisfied. These are: 1. That meaning is inferential role. 2. That there is no analytic/synthetic distinction. 3. That meaning is compositional. If 1-3 are not simultaneously satisfiable, at least one of them must be abandoned. We consider the question of which to give up, and of what the implications of doing so are likely to be. SATURDAY AFTERNOON JOHN F. SOWA: "Matching Logical Form to Linguistic Form" (abstract not available) BARBARA L. SPEICHER "Disentangling Conceptual and Linguistic Knowledge" Language is the principal mediator of thought and one of the few vehicles with which to explore abstract conceptual structures. Cognitive psychologists use linguistic evidence to study psychological functions such as memory and categorization and to construct models of knowledge representation. However, researchers in cognitive psychology seldom address how to disentangle conceptual and linguistic knowledge. In fact, the field seems to assume that the two systems are isomorphic. The related field of neurology provides insights into the relationship between cognition and language. Findings from both split-brain and aphasic populations encourage a separation of linguistic and conceptual structures. Specifically, Antonio Damasio's neurological theory of convergence zones is presented and used to explain the differential cognitive and linguistic abilities of neurologically impaired individuals such as split-brain populations and aphasic populations. The paper analyuzes both simple concepts and complex conceptual structures known as scripts. BARBARA ABBOTT and LARRY HAUSER "Natural Language and Thought" Hauser defends the proposition that our languages of thought are public languages. One group of arguments points to the coincidence of clearly productive thought with overt possession of recursive symbol systems. Another group relies on phenomenological experiences of mental discourse and making thoughts physical. A third group cites practical considerations, e.g. Occam's razor and the `streetlight principle' (look under the lamp) motivating looking for instantiations of outer languages in thought first. Abbott points to the literature and adduces a number of specific replies to Hauser. Examples of productive behavior showing thatnatural language is not necessary for productive thought includeproblem solving by chimpanzees, dreams, and feral human cases (Genie). On phenomenological and practical grounds, Abbott argues that communication of thoughts should be trivial if the inner language is the outer language, but it is not; the decryption analogy Hauser uses to apply the `streetlight principle' is flawed; and Occam's razor doesn't cut any ice with Mother Nature. SUNDAY MORNING MICHAEL TARR "Behavioral and Computational Constraints in Human Shape Representation" Do visual representations use an object-centered or viewer-centered reference frame? Studies suggest that recognition is orientation-dependent under many circumstances. The resulting theory, Multiple-Views-Plus-Transformations, hypothesizes that recognition is achieved by using a mental transformation to match input shapes to object representations in a viewer-centered reference frame. Moreover, these representations are orientation-specific, e.g. "views", and are stored according to the frequency of occurrence of an object in a particular orientation. However, familiarity is not the only factor that determines represented views. First, there is evidence that views are contingent upon the frequency with which other objects appear at particular orientations. Representations of familiar objects in novel views may arise as a result of the frequent appearance of an object's visually similar cohorts. Second, there is evidence that views are contingent upon the geometry of an object. The likelihood of a representation arising increases with the distinctiveness of visible surfaces at each orientation -- novel orientations are likely to be represented to the extent that their geometry is unique, while orientations in which the geometry differs only slightly from that depicted in preexisting views are unlikely to be represented. K. N. LEIBOVIC "Brain Mechanisms for Perceptual Representation" The brain is designed on a pattern of converging and diverging fiber tracts with their associated broadly tuned receptive and responsive fields. This puts certain constraints on the processing, transmission and representation of information. The properties of perceptive fields and target cells are taken as neural analogs of cognitive and logical operations. Analysis and synthesis can then be carried out in parallel; and the neural representations of elementary constituents and categorical constructs can be grounded in associational programs of activity in groups of cells. WHITMAN RICHARDS "Is Perception for Real?" What is the relation between the "external" world and our conceptualization of this world? At one extreme an independent external reality is denied, whereas at the other, an external reality is a requirement for any conceptualization. Perception lies at the heart of this controversy: can our percepts really reflect (or approximate) the true structure of the world independent of our observations or not? To address this question we need a clear understanding of just what a percept is and what it entails. I offer one definition and provide support for this choice using examples from vision (Jepson & Richards 1991). For our percepts to be useful, enabling us to predict the consequences of events and actions, certain conditions must be met. Two I will discuss are (1) the ability to manipulate representations or internal models, and (2) criteria for data (observations) which generate reliable interpretations. This second condition imposes limitations on the scope of useful percepts, and shows that percepts (perhaps like scientific theories?) are critically dependent upon a matching of cognitive concepts to modal regularities in the world.Mail to author|Respond to list|Read more issues|LINGUIST home page|Top of issue