The pro-drop parameter in second language acquisition revisited: A developmental account

This dissertation applies a particular theory of language acquisition and representation, Optimality Theory (Prince and Smolensky 1993, Grimshaw 1997), and a particular learning algorithm within this theory, the Constraint Demotion Algorithm (Tesar and Smolensky 2000), to the problem of how second language acquisition of pro-drop takes place for learners whose first language does not instantiate the grammatical properties traditionally associated with pro-drop.; The overarching goal of this study is to provide an account of the developmental stages in the second language learning of three grammatical properties: null subjects, inversion, and that-trace. Although there is no lack of such accounts from earlier generative perspectives, the need remains for a comprehensive developmental account from an Optimality-theoretic perspective. This dissertation begins to address that need.; The study here is based on several empirical tests (a translation task, a pilot study, and a grammaticality judgment task) that were administered to 370 adult native English speakers studying Spanish at the University of South Carolina or the Pennsylvania State University. Each task was designed to investigate learner competencies regarding null subjects, inversion, and that-trace. A key conclusion from these studies is that the acquisition of Spanish by native speakers of English involves a reranking of universal syntactic and discoursal constraints in these languages. Specifically, this dissertation argues that acquisition of Spanish occurs through the demotion of certain syntactic constraints in the English native grammar so that these constraints are dominated by discoursal constraints in the Spanish second language grammar.; This cross-sectional study not only tracks learners through developmental stages, but it is also theory driven, because the theory of grammar used in this dissertation permits specific predictions about the interaction and relative importance of constraints in Spanish and English and, ultimately, of the acquisitional route learners take. The application of Optimality Theory to interactions between discourse and syntax in second language learning represents a new and potentially productive line of inquiry that may advance our understanding of both second language learning and grammatical theory.