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Center for Cognitive Science The Puzzle of the Mind |
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| Fall
1998 Colloquia
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| Regular
colloquia are Wednesdays, 2:00-4:00 p.m., 280 Park Hall, North (Amherst)
Campus, and are open to the public. Refreshments are served.
Other colloquia
and our distinguished speaker are on different days.
Abstracts Wednesday,
September 9, 1998 LEONARD
TALMY, Ph.D. "Relating Language to Other Cognitive Systems" An important research direction in cognitive science consists of cross-comparing the forms of organization exhibited by different cognitive systems, with the long-range aim of ascertaining the overall character of human cognitive organization. Relatively distinct major cognitive systems of this sort would seem to include: language, (different modalities of) perception, reasoning and understanding, affect, attention, memory, and cultural structure. Much of my work, in particular, has sought to relate the conceptual structuring exhibited by language to the structuring that is exhibited by other cognitive systems. The general finding is that each cognitive system has some structural properties that may be uniquely its own; some further structural properties that it shares with only one or a few other cognitive systems; and some fundamental structural properties that it has in common with all the cognitive systems. It appears that each such cognitive system resembles and interacts with other cognitive systems more than is envisaged by the strict modularity notion. I term this view the "overlapping systems" model of cognitive organization. To illustrate, both language and visual perception have in common such structuring factors as the schematization of spatial relations between objects. But some factors with a significant structural role in visual perception -- such as symmetry, rotation, and dilation -- are at best minimally represented in the closed-class forms of languages. And conversely, linguistic closed-class forms express such categories as `reality status' -- e.g., inflections that represent a proposition as factual, conditional, potential, or counterfactual -- that have little part in visual perception. The talk will mainly examine this partial overlap between language and vision. If time permits, it will proceed to comparisons of language with the affect system, the culture system, and the understanding system, and end by examining structuring factors that appear to operate across all the major cognitive systems. -------------------------------------------------------------------------------- Wednesday,
September 16, 1998 Department
of Psychology "The Emergence of Grammar from Perspective-Talking" We can think of language as a system that allows human beings to assume and enact alternative specifically human perspectives that are grounded on the realities of physical existence. Perspective-taking operates on four distinct levels that correspond to major levels of primate cognition. These four levels are: affordances, spatio-temporal reference frames, causal action chains, and social frames. Affordances allow us to ground our understanding of particular lexical items on sensory and motor realities. Spatio-temporal reference frames allow us to generalize the ego-centered perspective to object-centered and environment-centered reference frames. The linguistic expression of spatio-temporal frames is concentrated on adverbial phrases, but the results affect the whole pattern of accessibility for mental models. Causal action chains allow us to understand the actions of objects in terms of movements and changes of our own bodies. The linguistic expression of these chains strongly influences basic processes in clausal grammar. Social frames allow us to shift between the perspectives of different social actors. The linguistic expression of this level of perspective-taking focuses on discourse structure and the interpretations of socially complex lexical items. Although these four systems are supported by partially separate dynamic neural pathways, the overall control of perspective-taking and perspective shifting is achieved through the interaction of language with prefrontal processes. The full interaction of language with the four embodied systems gives rise to the construction of an internalized homunculus that is then available for the control language comprehension, language production, inner speech, and problem-solving. By tracing through the on-line incremental processing of sentences during production and comprehension, we can observe the operations of perspective-taking as it threads across alternative perspectives on these four levels. -------------------------------------------------------------------------------- Wednesday,
September 23, 1998 Department
of Geogrpahy, BARRY SMITH Department of Philosophy and Center for Cognitive Science "Cognition, Ontology and Geographic Information Science" Geographic categories are structured differently from categories for closed, portable objects at table-top scales. Geographic objects are not merely located in space, they are tied to space intrinsically, in a manner that implies that they inherit from space many of its structural (part/whole, topological, geometrical) properties. In addition, to a much greater extent than in the world of table-top objects, the realization that a thing or type of thing exists at all may have individual or cultural variability. Moreover, the boundaries of geographic objects are themselves salient phenomena for purposes of categorization. Such boundaries may be crisp or graded, open or closed, and they may be subject to dispute. Mark and Smith will describe their current work on geographic categories and its relation to the work of Rosch and others. They will also outline plans for the empirical testing of a general ontological theory of geographic objects and categories, and set these plans in relation to other cognitively oriented research in the NCGIA, including the recently approved interdisciplinary training grant under the NSF's IGERT scheme. -------------------------------------------------------------------------------- Wednesday,
October 7, 1998 PAUL THAGARD, Ph.D. University
of Waterloo Emotional Analogies: How People Use Analogies in Persuasion,Empathy, and Humor People frequently use analogies when they are trying to persuade others to agree with them, when they are trying to understand each other, and when they are making jokes. This talk will present a cognitive theory of the role of emotions in such analogies. The theory extends previous computational accounts of coherence and analogy to encompass emotion, and proposes a novel understanding of analogical inference. -------------------------------------------------------------------------------- Wednesday,
October 21, 1998 JONATHAN DOSTROVSKY, Ph.D. University
of Toronto BRAIN MAPS AND PHANTOM LIMBS It is now well known from animal studies that the representation of the body's surface, at least at the cortical level, is quite plastic. In particular, following removal of input from a given body region, the representations of the surrounding regions expand into the deafferented region. However the functional/perceptual consequences of these alterations are not known. Furthermore, following amputation of a limb most people retain an image of the amputated limb and can experience sensations in the phantom. The underlying mechanisms are not well understood. I will describe studies involving recordings of sensory neurons and the perceptual effects of electrical stimulation at such sites in the thalamus of awake patients undergoing stereotactic surgery for relief of pain following amputation. The findings provide new insights regarding plasticity and phantoms. -------------------------------------------------------------------------------- Wednesday,
October 28, 1998 DAVID HUNTER, Ph.D. Department
of Philosophy States and Identity The Identity Thesis in the philosophy of mind holds that a person's mental states are identical with physical states, typically brain states. Proponents of this view have claimed that the identities in question are empirical and contingent truths, and that a given mental state might, in different species or different members of one species, be identical with physical states of different types. This thesis raises important questions about the nature of states, and about the logic of identity claims involving states. Just what is a state, and what does it mean to say that a mental state is identical with a brain state? I begin by proposing an account of the nature and logic of states, according to which states are simply property instantiations. I distinguish several versions of the Identity Thesis and argue that, given this account, the Identity Thesis does not support the claims made by its proponents. I suggest that some of these are best viewed as concerning the claim that mental states supervene on physical states. I then argue that rejecting the account of the logic and ontology of states yields identity statements that are but a stylistic variant on statements about the supervenience of the mental on the physical. My tentative conclusion is that physicalists about the mind are better served by defending a supervenience claim, than an identity claim. -------------------------------------------------------------------------------- 280
Park Hall
DANA H. BALLARD, Ph.D. Department
of Computer Science Deictic Behaviors We argue that a computational theory of the brain will have to address the issue of computational hierarchies, wherein the brain can be seen as using different instruction sets at different spatio-temporal scales. As examples, we describe two such abstraction levels. At a timescale of one-third of a second, a language is needed to address the way the brain directs the physical resources of its body. An example of these kinds of instructions would be those used to direct saccadic eye- movements. Interpreting experimental data from this perspective implies that subjects select eye-movements in a special strategy to avoid loading short-term memory. This constraint has implications for the organization of high- level behavior. At a timescale of 50 milliseconds we consider a model of instructions which capture the details of programming the individual eye-movements themselves. This model makes extensive use of feedback. The implications of this are that brain circuitry may be far more dependent on the context of a task than traditionally proposed.
280
Park Hall ELLEN BIALYSTOK, Ph.D. Department
of Psychology Languages,
Scripts, and Bilingualism: In order to read, children must understand that the relationship between the written forms and the meanings they represent is symbolic. Thus, children's mental representation of the nature and function of print needs to be represented symbolically as well. This symbolic relationship between print and meaning includes two insights. The first is the general principle that the written forms wholly determine the meaning; the second is the specific principle that determines how the forms signify meaning in that script. In alphabetic languages, for example, letters stand for sounds. Both insights come after children appear to have learned the written forms. Several studies are reviewed that show that children know the forms (e.g., letters) before they know that they are symbols and that bilingual children come to understand aspects of the symbolic function of these forms earlier than monolingual children do. Further, the writing systems used in the two languages of the bilingual determine how the development of each of these insights will proceed. Finally, the pattern performance demonstrated by the bilinguals is discussed in terms of different processes of representation and attention established by bilingual children from a very early age. -------------------------------------------------------------------------------- 280
Park Hall RALPH H. BENEDICT, Ph.D. Department
of Neurology Functional
Neuroimaging of Auditory Attention The general emphasis of this colloquium is the relationship between cognition and cerebral function. While no unitary model of attention has gained wide acceptance in the cognitive science literature, scientists have repeatedly emphasized three aspects or components of attention: (1) capacity demand, (2) vigilance, and (3) selection. Functional neuroimaging methods provide a means of determining the cerebral correlates of theses constructs. Neuropsychological models have been proposed (eg Posner) which account for attention task performance in humans, but these models have emphasized the visual modality. The degree to which Posner's model accounts for attention in a different modality (eg audition) is not known. The results of a preliminary study on auditory attention using positron emission tomography (PET) will be presented. It is concluded that an area of the brain, the anterior cingulate gyrus, can be identified which is active during high-capacity demand attention, across sensory modalities. This anterior brain region is distinguishable from posterior regions which appear to be involved in the sensory aspects of cognitive processing, but not in attention, per se. An intriguing area for future research concerns the overlap (anatomically speaking) between regions concerned with high- capacity demand attention and motor function. An experiment designed to isolate these functions will be presented. -------------------------------------------------------------------------------- Wednesday,
November 25, 1998 SIDNEY SEGALOWITZ, Ph.D. Department
of Psychology Pushing
around the P300 event-related potential: Scalp EEG can be used to reflect some aspects of information processing in the brain, especially when segments of EEG are time-locked to stimulus presentation and then averaged, forming an averaged event-related potential (ERP). One of the major components of the ERP is the P300 (or P3) peak, which is traditionally thought to reflect the updating of stimulus information in working memory. I will present a series of studies that show that the P300 reflects attentional allocation rather than memory per se; I will then apply present results from our studies using this paradigm to see the effects of alcohol, caffeine, and mild head injury on the allocation of attention. -------------------------------------------------------------------------------- Wednesday,
December 9, 1998 STUART SHAPIRO, Ph.D. Department
of Computer Science and Engineering and Embodied Cassie We have enhanced a computational cognitive agent by embodying it with real and simulated bodies operating in real and simulated worlds. This has allowed us to experiment with various ways that embodiment influences the creation and meaning of the agent's beliefs and other terms in its knowledge base, including: symbol-grounding by perception and action; first-person privileged knowledge; the representation and use of indexicals; having a personal sense of time; and low-level bodily awareness. |
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