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Center for Cognitive Science The Puzzle of the Mind |
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2002 Colloquia Schedule
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September October November December |
Regular colloquia are Wednesdays, 2:00pm - 4:00pm, at 280 Park Hall, North Campus and are open to the public. Refreshments are served. For related CogSci events please go to the Dept. of Computer Science and Engineering and the Dept. of Philosophy. If you are interested in receiving email announcements of each event, please subscribe to one of our email mailing lists.
Abstracts Wednesday,
September 4, 2002 280 Park Hall, North Campus Helen
Mayberg, M.D. "In
Search of Depression Circuits: Resting-state abnormalities in regional glucose metabolism and blood flow using PET have been identified in patients with depression, including changes associated with treatment and clinical recovery. Although the relative contribution of individual regions varies as a function of clinical state, involvement of cortical, paralimbic and subcortical regions is seen across studies. Cortical deficits normalize with treatment (state effects); paralimbic and subcortical regions show a more complex state-trait pattern. Changes in these same regions are also seen with transient provoked sadness, with differences discriminating controls from depressed patients. Common patterns seen in both unipolar and bipolar patients suggest convergent pathways mediating disturbances in mood across diagnoses including a more generalized vulnerability to emotional stressors across patient groups. Formal testing of disease-specific and state-specific functional interactions among regions in this depression "network" provides a complementary perspective for future studies examining mechanisms underlying treatment response, relapse and disease vulnerability. For a printable version of this file click here
Wednesday,
September 11, 2002 280 Park Hall, North Campus Gerald
Penn, Ph.D. "Topological Parsing" Why is parsing so difficult in freer word-order (FWO) languages? The standard answer goes something like this: if the order among a phrase structure rule's daughter categories is not specified, then there will be exponentially many orderings to consider. A great many more presuppositions carried by phrase structure are mistaken than just linear order, however - some of them quite fundamental, such as what a category represents. This talk summarises our progress on using insights from descriptive and generative linguistics to formalise new parsing models for FWO languages. Of particular benefit has been the recent re-examination of Slavic and Germanic syntax within HPSG and dependency grammar, which distinguishes at least two different varieties of constituency. This distinction can be used during parsing, both for efficiency and for accommodating prosodic and discourse-level constraints into a syntactic model. For a printable version of this file click here
Wednesday,
September 25, 2002 280 Park Hall, North Campus Ann
Clock Eddins, Ph.D. "Cortical
Dynamics Associated with the In recent years, there has been an increasing use of functional neuroimaging techniques to help improve our understanding of the brain regions involved in a variety of cognitive, sensory, and motor tasks. Specifically, we have been using positron emission tomography (PET) to study the relationship between auditory perception and cortical activation during discrimination tasks involving complex auditory stimuli. In this presentation, we will review results from two projects that have demonstrated dynamic cortical activation patterns that are dependent on both the detailed features of the sensory input as well as the cognitive demands of the discrimination task. For a printable version of this file click here
Wednesday,
October 2, 2002 280 Park Hall, North Campus Marie-Ann
Lescourret, Ph.D. "The Prehistory of Symbolic Forms" How can we understand a work of art? How is it that a work of art can be meaningful to us? My puzzlement arises from the fact that so many people can be touched by artistic productions elaborated in unknown languages, from unknown countries, from unknown cultures, and belonging to other times. How is it that we can be kept amazed, silent, gazing, in front of a painting by Raphael, or a symphony by Mozart, or an Amerindian statue? We can find descriptions of such processes of understanding in history and in anthropology, but also in what Wittgenstein defines as the psychology of philosophy. I will show that the art historian Aby Warburg can throw light on the question of what happens in the process of understanding in the human brain. Warburg, also a philosopher and a psychologist, wondered why the same patterns always reappeared in different works of art, be it those of the American Indians, or those of the Italian Renaissance. The answer he gives to this question postulates the existence of a common human mental structure at work in the making and the understanding of a work of art. Marie-Anne Lescourret is associate professor of aesthetics in the University of Strasbourg, France. She is the author of books on Rubens, Goethe, Levinas and Paul Claudel, and the translator of works by Newton and Wittgenstein.
For a printable version of this file click here
Wednesday,
October 9, 2002 280 Park Hall, North Campus Stuart Shanker,
Ph.D. "Ape Language in a New Light" In recent years we have seen a dramatic shift, in several different areas of communication studies, from an information-theoretic to a dynamic systems paradigm. In an information-processing system, communication, whether between cells, mammals, apes, or humans, is said to occur when one organism encodes information into a signal that is transmitted to another organism that decodes the signal. In a dynamic system, all of the elements are continuously interacting with and changing in respect to one another, and an aggregate pattern emerges from this mutual co-action. Whereas the information-processing paradigm looks at communication as a linear, binary sequence of events, the dynamic systems paradigm looks at the relation between behaviors and how the whole configuration changes over time. One of the most dramatic examples of the significance of shifting from an information-processing to a dynamic systems paradigm can be found in the debate over the interpretation of recent advances in ape language research (ALR). To some extent, many of the early ALR studies reinforced the stereotype that animal communication is functional and stimulus-bound, precisely because they were based on an information-processing paradigm that promoted a static model of communicative development. But Savage-Rumbaughs recent results with bonobos has introduced an entirely new dimension into this debate. Shifting the terms of the discussion from an information-processing to a dynamic systems paradigm not only highlights the striking differences between Savage-Rumbaughs research and earlier ALR studies, but further, it sheds illuminating light on the factors that underpin the development of communication skills in great apes and humans, and the relationship between communicative development and the development of language. For a printable version of this file click here
Wednesday,
October 16, 2002 280 Park Hall, North Campus Stephen
Grossberg, Ph.D. "Cortical
Dynamics of Learning, Speech Perception, What is the neural representation of a speech code as it evolves in time? How do listeners integrate temporally distributed phonemic information into coherent representations of syllables and words? How does the brain extract invariant properties of variable-rate speech? More generally, what sorts of mechanisms encode temporal order during a complicated task like speech perception? This talk will describe an emerging neural model, variously called the PHONET, ARTPHONE, and ARTWORD model, that suggests answers to these questions, while quantitatively simulating challenging data about speech and word recognition. In this model, rate-dependent category boundaries emerge from feedback interactions between a working memory for short-term storage of phonetic items and a list categorization network for grouping sequences of items. The conscious speech and word recognition code is suggested to be a resonant wave, and a percept of silence is proposed to be a temporal discontinuity in the rate with which such a resonant wave evolves. Such a wave emerges when sequential activation and storage of phonemic items in working memory provides bottom-up input to unitized representations, or list chunks, that group together sequences of items of variable length. The list chunks compete with each other as they dynamically integrate this bottom-up information. The winning groupings feed back to provide top-down support to their phonemic items. These top-down expectations amplify and focus attention on consistent working memory items, while suppressing inconsistent working memory items. Feedback establishes a resonance which temporarily boosts the activation levels of selected items and chunks, thereby creating an emergent conscious percept. Because the resonance evolves more slowly than working memory activation, it can be influenced by information presented after relatively long intervening silence intervals. Variations in the durations of speech sounds and silent pauses can hereby produce different perceived groupings of words, and future sounds can influence how we hear past sounds. What functional reason explains why multiple levels of auditory processing may use resonant dynamics? A proposed answer is indicated by the fact that all the models have the acronym ART in their names. This is because they are special cases of Adaptive Resonance Theory. ART proposes how the processes whereby our brains continue to learn about a changing world in a stable fashion throughout life lead to conscious experiences. These processes include the learning of top-down expectations, the matching of these expectations against bottom-up data, the focusing of attention upon the expected clusters of information, and the development of resonant states between bottom-up and top-down processes as they reach an attentive consensus between what is expected and what is there in the outside world. It is suggested that all conscious states in the brain are resonant states, and that these resonant states trigger learning of sensory and cognitive representations. Thus, the speech models outlined above are proposed to be specialized versions of ART mechanisms for stably learning about temporally evolving information about the world. For a printable version of this file click here
Wednesday,
October 23, 2002 280 Park Hall, North Campus Ann
Bisantz, Ph.D. "Taking
a Brunswikian approach to modeling Brunswik's theories of human judgment, and their later mathematical formulations, have been widely applied in areas such as social judgment theory and medical diagnosis. More recently, researchers have begun applying this descriptive model of decision-making to human and automated judgment agents in complex, dynamic systems. This talk will discuss the modeling approach, and provide example applications and modeling extensions, as well as some resultant design implications, in command and control, process control, and aviation environments. For a printable version of this file click here
Wednesday,
October 30, 2002 280 Park Hall, North Campus David Shore,
Ph.D. "Confusing the Mind by Crossing the Hands: The Psychophysics, Neuropsychology and Neuroimaging of Tactile Remapping" Interaction with our environment relies heavily on the use of our hands, which serve both as tools for manipulating objects and as receptor surfaces for perceiving those objects. This dual role means that the hands move constantly within peripersonal space as different postures are adopted. Tactile stimuli presented to the hands can be coded either in terms of their relative position on the body surface (a somatotopic frame of reference), or relative to some environmental (e.g., allocentric) or body-centered frame of reference. The present talk explores the abilities and limitations of the brain to accommodate various postures-linking visual with tactile information. Visuotactile illusions, tactile temporal order judgments, cross-modal congruency tasks (with normals and split-brain patients), and functional Magnetic Resonance Imaging are all used to demonstrate these factors in tactile remapping. For a printable version of this file click here
Wednesday,
November 6, 2002 280 Park Hall, North Campus Barry Smith,
Ph.D. "SNAP and SPAN" Many philosophers believe that truth is to be understood in terms of a relation between true sentences, on the one hand, and facts or states of affairs in the world, on the other. The latter are the truthmakers for the former. But consider the sentence: "John has been located in Atlanta for 35 years." What is it, in the world, which makes this sentence true? Well, perhaps some complex whole involving John, Atlanta, and a location relation stretching across 35 years. But John has exchanged all the molecules in his body many times in this 35 year period, and Atlanta may well have exchanged all its buildings. What, then, are the bearers of the location relation in the given case? I will argue that the impossibility of providing an answer to this question demands an overhaul of our common conceptions of language and ontology. Briefly: that nouns and verbs are in order as they stand (as, in the medical domain, anatomy and physiology are in order as they stand), but that the sentence is marked by the ontological equivalent of original sin. For a printable version of this file click here
Wednesday,
November 13, 2002 280 Park Hall, North Campus Eduardo
Mercado III, Ph.D. "Mammalian
Memories of Memory for personal experiences (episodic memory) is thought to rely on the ability to mentally travel back in time to consciously re-experience past events. Based on a lack of evidence of mental time traveling in non-humans, it has been proposed that this ability is unique to humans. This talk will present an alternative viewpoint. We propose that many mammals store and recall memories of personal experiences, and that cortical networks mediate this ability. Experimental data from dolphins, rats, and a chimpanzee demonstrate that non-humans can report on actions they have recently performed. Dolphins, in particular, can be trained to repeat prior actions on command, including self-selected actions and actions performed with particular objects. The recent discovery of "mirror neurons" in primate cortex, which fire both when a monkey performs an action, and when the monkey observes an action, provides important clues about how past actions are represented in memory. For a printable version of this file click here
Wednesday,
November 20, 2002 280 Park Hall, North Campus Michael
Noonan, PhD. "Evidence of cognitive processes in killer whales: A program of research underway at Marineland of Canada" Killer Whales are characterized by long lives, complex social structures and one of the largest brains of any species on earth. This talk will present findings from a program of study on Killer Whales underway at Marineland of Canada that suggest a degree of convergence in the cognition of cetaceans with that of primates/humans. The talk will concentrate on recently completed work that assessed the whales' ability to make "relative numerousness judgments" as an index of their ability to cope with quantity as a stimulus dimension. The findings show that these animals can indeed cope with quantitative discriminations in this way and in fact show their abilities in this regard to meet or exceed that shown by any other non-human species. Furthermore, analysis of their errors during task acquisition suggest a "Piagetian" pattern analogous to that shown by human children. The talk will then include preliminary reports of work underway on mirror self recognition in killer whales, and on left-right asymmetry in response preference, both of which also imply convergence with primate/human cognition. The talk will end with new behavioral evidence suggestive of "intentionality" on the part of the whales and a discussion of how this additional, typically-human trait might be experimentally verified in Killer Whales. For a printable version of this file click here
Wednesday,
December 4, 2002 280 Park Hall, North Campus J.
David Smith, PhD. "The
Categorization Dilemma That Airport X-ray screeners at airport security checkpoints perform an important categorization task in which they detect targets amidst multiple, overlapping images. Their performance must be evaluated to gauge the security system's adequacy. A natural and feasible approach to evaluation is to build a library of target images and test screeners by sampling from these. We built the Screener categorization task to assess this library approach from the perspective of the categorization literature. In the Screener task, participants search for members of target categories in complex displays like those that luggage presents. We find that when targets are sampled from a library with repetition so that familiarity develops, participant screeners rely on recognizing familiar targets instead of applying category-general knowledge. These results ground experimentally similar observations that have been made within non-domestic aviation security (i.e., observations of familiarity effects in the detection of ecological threat images). These effects may illuminate the processes of categorization under conditions of visual complexity. They also suggest that the library approach to evaluation risks failures of security wherein unfamiliar targets go undetected. We consider an alternative approach. For a printable version of this file click here
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