Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, February 1999.Includes bibliographical references (p. 120-125).This dissertation considers ambiguity resolution in regard to two issues. First, it investigates factors that lead the human parser to favour some types of interpretations over others when faced with some types of ambiguous input. Second it examines the reanalysis process that takes place when initial biases lead to incorrect interpretations. The first part of the dissertation (Chapter 1) proposes that reanalysis is a process that requires the maximal satisfaction of constraints (similar to first pass parsing as in Gibson & Pearlmutter, 1998; MacDonald, Pearlmutter & Seidenberg, 1994) rather than the minimization of the number of operations involved as has been suggested previously (Frazier, 1994; Fodor & A. Inoue, 1994). Three experiments in Japanese using main/embedded clause ambiguities are reported in support of this claim. The second part of the dissertation (Chapters 2, 3 and 4) uses a well-established generalization as a starting point, namely, that a modifying phrase is preferentially attached to the closest available site. A recent question in the literature has been to determine ways of parameterizing this principle in order to account for cross-linguistic variations observed in the attachment of relative clauses (Cuetos & Mitchell, 1988). In Chapter 2, the potential parametrizations that may explain the phenomenon at hand are restricted based on data from Brazilian Portuguese. In Chapter 3, an experiment in Japanese investigates the locality preference in this head-final language. Finally, in Chapter 4, it will be suggested that ambiguities in relative clause attachment are not only well suited to investigate cross-linguistic phenomena but also various properties of the human parser that lie beyond the realm of grammatical well-formedness, and two on-going projects are briefly described.by Edson T. Miyamoto.Ph.D.