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Title: Human text processing and models of knowledge representation
Author: Patel, M. J.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1991
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Two experimental studies on human text processing and knowledge representation are reported. They are designed to explore the nature of cognitive processes in working memory and long term representations associated with the resolution of reference in texts. Resolution of references occurs when properties of distinct individuals are bound together in memory. Stenning, Shepherd and Levy (1988) propose that binding is achieved by recruiting existing general knowledge associations based on the semantic structure of texts. They present models of representation structures in a novel Memory for Individual Task (MIT), and show that these models can explain certain patterns of retrieval error frequencies. A statistical model of construction of representation processes which account for a particular pattern of reading times in terms of key aspects of the structure of MIT texts is also presented. The reading times results of the first MIT experiment, in which the order of switches in reference between individuals is unpredictable, is presented together with as extended construction processing model which capture phenomena of reference changes. The new models show that unpredictable reference changes cost time as a function of the complexity of the individual to which reference is switched, without disrupting the modular account of processing centred on referenced individual reported by Stenning, Shepherd and Levy (1988). Analysis of recall errors reveal an effect of presentation order, which results in confusion over identity of individuals' properties, providing a basis for a distinction between 'primary' and 'secondary' individual, each requiring different syllabic rehearsal processing. These working memory processes are incorporated in a model which reveals interaction between rehearsal and semantic processes. The error data is further analysed with respect to logically constraining solutions to representations of bindings with 'direct' and 'indirect' structures. Direct systems represent binding by structural devices referring to individual identities in their representation; indirect systems represent binding only through quantificational facts. Both direct and indirect models are developed and the latter one shown to be at least as good a fit to the data as the former, which suggests that solution to the binding problem is represented in a distributed manner closer to PDP systems. Much of the theoretical underpinning of the findings of the first study, is dependent on aspects of the semantic structures which reflect regularities in the temporal order of descriptions of individuals in MIT texts. The second study investigates the extent to which such regularities facilitated the sorts of structures constructed in representations of solutions to the binding problem, and interaction between temporal order of presentation and working memory processes. Analyses of reading times show that, while order of presentation of properties has no significant effect on working memory processes, differences in availability of information about higher level semantic structure does require extra processing. A statistical model which factors out some of this processing load as due to specific changes in the semantic structure of MIT texts is presented.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available