This thesis explores the role of age in second language (L2) acquisition and first language (L1) attrition. The focus is on Voice Onset Time (VOT) in the production and categorical perception of word-initial L1 and L2 stops in highly advanced L1 Spanish learners of L2 Swedish. Using as the point of departure a maturational constraints perspective and the Critical Period Hypothesis (CPH), Study I examines the impact of age of onset (AO) of L2 acquisition on the production of L2 Swedish voiceless stops. The results show that there are AO effects even in the speech of highly advanced L2 learners and that the incidence of nativelike L2 learners is considerably lower than earlier assumed. However, conclusions like these are only possible when speaking rate is accounted for, thereby highlighting the importance of speaking rate effects on VOT as a measure of nativelikeness. Like Study I, Study II reveals age effects on the same L2 learners’ categorical perceptions of L2 Swedish stops. Moreover, after combining the results with the data from Study I, the incidence of nativelike behavior drops remarkably with no late L2 learner performing within the range of native-speaker production and perception. The results suggest that L2 acquisition of phonetic/phonological aspects is especially sensitive to AO effects. It is concluded that theories on maturational constraints, including the CPH, cannot be refuted on the basis of the present data. Study III concerns the same participants’ production and perception of L1 Spanish stops. Age of reduced contact (ARC) is identified as an important predictor for L1 attrition and retention of voiceless stop production, although not of stop perception. This discrepancy is related to different activation thresholds as proposed by the Activation Threshold Hypothesis (ATH). It is further suggested that early bilinguals are more dependent on high-frequency L1 use than late bilinguals when compensating for age effects, but only in production. / <p>At the time of doctoral defence the following papers were unpublished and had a status as follows: Paper 1: Accepted. Paper 2: In press. Paper 3: Manuscript.</p> / Age of onset and ultimate attainment in second language acquisition, The Bank of Sweden Tercentenary Foundation, grant no. 1999-0383:01 / First language attrition in advanced second language speakers, Swedish Research Council, grant no. 421-2004-1975

Text in English / One of the critical challenges associated with migration is a need to acquire a destination language, which has never been an easy experience for immigrants. This study aims at exploring and analysing experiences of Malawian immigrant labourers in their process of acquiring spoken skills of isiZulu in Durban. In order to understand the phenomenon under investigation better, this study used a qualitative research approach and adopted a phenomenological research design. The data for this study was collected using semi structured one-to-one interviews. The data were analysed using content analysis method and was approached and discussed in light of Schumann‟s (1986) Acculturation Model and frame works and a destination–language acquisition model of Chiswick and Miller (2001). Empirical findings from this study have shown that adults; just like children, are also capable of mastering a second language if they can manage both social and psychological factors that impede acquisition. / Linguistics and Modern Languages / M.A. (Linguistics)

Text in English / One of the critical challenges associated with migration is a need to acquire a destination language, which has never been an easy experience for immigrants. This study aims at exploring and analysing experiences of Malawian immigrant labourers in their process of acquiring spoken skills of isiZulu in Durban. In order to understand the phenomenon under investigation better, this study used a qualitative research approach and adopted a phenomenological research design. The data for this study was collected using semi structured one-to-one interviews. The data were analysed using content analysis method and was approached and discussed in light of Schumann‟s (1986) Acculturation Model and frame works and a destination–language acquisition model of Chiswick and Miller (2001). Empirical findings from this study have shown that adults; just like children, are also capable of mastering a second language if they can manage both social and psychological factors that impede acquisition. / Linguistics and Modern Languages / M. A. (Linguistics)