This project speaks to the prospect that, under conditions of disues, a speaker may not maintain his/her first language. Recent research into adult language attrition, or language loss, questions the assumption that a first language, once acquired, remains stable in spite of exposure to, and the acquisition of, an additional language (or additional langueges). It also raises important questions that help describe and explain the nature of linguistic attrition, as well as shed light on the mental representation of human language. The goal of this project is to contribute to the investigation of both where and why a first language may be lost. Specifically, the predictions of the Interface Hypothesis as applied to language attrition will be tested. This hypothesis predicts that human language is most susceptible to attrition at points that interface with domains of cognition that are external to language proper, such as those properties which require a real-time knowledge of the particular discourse context. Properties that lie internally to the linguistic system, such as those that deal strictly with meaning or syntax, are less likely to erode. Within this framework, the culprit of attrition is hypothesized to be either direct interference from additional language(s) or certain language processing deficits inherent to bilingualism. The research team will carry out an intensive case study which tests the L1 grammar of an adult native speaker of Spanish after 25 years of uninterrupted exposure to Brazilian Portuguese. Both offline (written) and online (timed) methodologies are used to test knowledge of a number of properties at external and internal interfaces, as well as narrow syntactic properties, at points where the L1 and L2 converge and diverge. Monolingual native-speaker data serves as a basis of comparison. The results of this study will not only allow for an examination of possible domains of attrition but also for more precise look at the cause(s) of attrition.
This project aimed to test the predictions of the Interface Hypothesis as it relates to first language attrition (i.e., non-pathological language loss). It was a case studying, examining one principal participant whose first language was Spanish and lived in a Portuguese-language environment; additionally, two groups of monolinguals, one of Spanish speakers and the other of Portuguese speakers, served as baseline data. Judgments on the grammaticality, acceptability and interpretation of various sentences were collected via untimed or timed tasks. Control group participants took either the untimed or timed version of the tasks in their own language, while the principal participant complete all versions of the tasks in both languages. Extensive oral production data was also collected from the principal participant. The data showed that the Interface Hypothesis is not supported as a viable model of first language attrition. While the principal participant did show attrition of those linguistic properties which required both linguistic and extralinguistic knowledge (i.e. external interface properties), which is predicted by the Interface Hypothesis, there was also attrition of purely linguistic properties (i.e. internal interface and purely syntactic properties). Attrition of those properties which only use linguistic knowledge is not predicted by the Interface Hypothesis. Additionally, the principal participant showed attrition only when the property in question was divergent in Spanish and Brazilian Portuguese; in these cases, the participant behaved in line with the Brazilian Portuguese control group. This suggests that the specific language pairings should be taken into account when predicting the effects of attrition, at least in extreme cases such as this. First language attrition is understudied in generative linguistics. This dissertation project, although a case study, is one of the most in-depth examinations of attrition available.