SEMANTICS, DISCOURSE MODELS, AND THE RIGHT HEMISPHERE

University Of California Davis, Davis CA

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Abstract

The primary aim of text processing research is to specify the nature of readers' discourse representations and the processes that construct them. Readers represent a text in the form of a discourse model, a representation of the entities (e.g., people, objects, places) and events in a text and the relations among them. A discourse model is constructed incrementally; incoming language is analyzed against a background of knowledge structures consisting of representations of recent text input and general world knowledge. Much of the research in text comprehension has been aimed at understanding how and when readers access relevant world knowledge and integrate this knowledge into their developing discourse model. Relatively little attention has been devoted to understanding how the discourse model is neurally instantiated. One of our goals in this project is to investigate the right hemisphere's role in discourse processing using the theoretical concepts and paradigms that are standard in psycholinguistic and text-processing research. Our second goal is to examine hypotheses linking the right hemisphere's role in discourse processing to the nature of its lexical-semantic system. One hypothesis suggests that the right hemisphere represents words differently than does the left. More diffuse word representations in the right than in the left hemisphere supports priming of distantly-related concepts. These concepts support many of the inferences that are necessary to construct a coherent discourse model. A second hypothesis suggests that the right hemisphere processes words differently than does the left. Slower activation and decay in the right hemisphere relative to the left may be important in the elaboration and reinterpretation of the discourse model. The right hemisphere's role in discourse processing will be investigated among normal young adults, right- and left- hemisphere lesioned patients, and callosotomy patients. Discriminating between these hypotheses has important implications for understanding a number of disparate phenomena, including differences in semantic priming in the left and right hemispheres and differences in comprehension deficits that arise from left and right hemisphere damage.