Parameter resetting in adult second language acquisition: Inflectional richness and the null subject parameter

This dissertation examines the potential relationship between the principles and parameters model of Universal Grammar and adult second language acquisition. One of the parameters discussed within UG theory relates to the phenomenon of null subjects in certain languages. Spanish and Japanese, for example, though quite different in terms of their respective systems of verbal inflection, both allow phonologically unrealized subjects. The present study raises the following questions: When an individual whose first language allows null subjects undertakes the study of English (an obligatory-subject language), will differences in parameter settings create learning problems? Furthermore, what effect will the different levels of inflectional richness found in null-subject languages have on the acquisition of English?; Cross-sectional data were collected from 178 learners of English who were enrolled in the Intensive English Program at Indiana University. The participants were divided into three language background groups (Spanish-type null-subject languages, Japanese-type null-subject languages, and obligatory-subject languages) and four levels of grammatical proficiency. These learners completed a 48-item grammaticality judgment task containing randomly organized grammatical and ungrammatical English sentences. The ungrammatical test sentences included three categories of null subjects (referential pronouns, "it" expletives, and "there" expletives) which appeared in decontextualized (main clause null subject) and contextualized (subordinate clause null subject) discourse forms.; The results indicate that whereas all learners demonstrate gradual improvement in accuracy from lower to higher levels of proficiency, the Japanese-type learners are more successful at acquiring the English value of the Null Subject Parameter at lower proficiency levels. The Spanish-type learners have more difficulty with judgments of English null-subject sentences at lower levels, with distinct parameter resetting effects shown between lower and higher levels of proficiency. The learners from obligatory subject backgrounds show behavior that closely resembles that of the Japanese-type learners. These findings largely confirm the results of a number of previously conducted second language acquisition studies, as well as the author's pilot study. It is suggested that research such as this effectively brings together the fields of formal linguistics and applied linguistics.