Acquisition of morphosyntax in the adult second language: the phonology factor

The goal of this dissertation is to examine the ubiquitous challenge that adult second language speakers have in producing functional morphology, even at advanced stages of acquisition. Specifically, this study examines how native speakers of Spanish, Mandarin and Japanese use past tense and number morphology in English. To this aim, two current competing hypotheses are tested: the Interpretability Hypothesis, which states that certain aspects of syntactic knowledge (uninterpretable features) cannot be acquired after a critical period, resulting in target-deviant use of functional morphology, and the Prosodic Transfer Hypothesis, which claims that all aspects of syntax can be acquired, but that phonological transfer effects from the first language might be at the source of target-deviant use of functional morphology. Participants were selected according to a pre-established set of criteria in order to obtain similar linguistic profiles. Native speakers of American English also participated as controls. The experiments included proficiency tests, sentence completion tests and picture description tests.

Group and individual results were analyzed in order to determine the extent to which the Interpretability Hypothesis and the Prosodic Transfer Hypothesis could account for the observed patterns. The results of the experiments in this study strongly suggest that phonological factors can account for some of the observed target-deviant use of functional morphology, supporting the Prosodic Transfer Hypothesis. The results also suggest that ultimate acquisition of new uninterpretable features is possible, supporting the Prosodic Transfer Hypothesis and not the Interpretability Hypothesis. The study also stresses the idea that although phonological transfer effects cannot account for all the problems observed in second language functional morphology, it is vital that phonological factors be taken into account.