LEXICAL ACCESS IN BILINGUAL SPOKEN WORD PRODUCTION: EFFECTS OF LEXICAL INTERFERENCE

Abstract

When bilinguals decide to speak in one of their languages, parallel activation from both of their languages occurs. Selecting to speak in one language is therefore highly demanding since bilinguals have to constantly deal with the co-activation of translation equivalents in their other language, as well as interference from semantically related lexical representations in each language. Switching from one language to another poses the extra demand for a control mechanism to deal with cross-language activation. The aim of this thesis was to investigate the effects of semantic and cross-language interference on bilinguals’ lexical retrieval. In addition, the effects of language similarity and bilingual language profile on cognitive control abilities in language selection and switching were examined. Two groups of highly proficient bilinguals completed a detailed bilingual profile questionnaire: a group of Arabic-English bilingual with unrelated languages and a group of German-English bilinguals with closely related languages. Language switching performance in both groups of bilinguals was investigated in a picture naming paradigm. Lexical selection demands were manipulated by integrating a semantic blocking paradigm so that pictures were named in semantically heterogeneous versus homogeneous lexical selection contexts. Both groups of bilinguals were slower in the homogeneous as compared to the heterogeneous contexts. Importantly, a significant interaction of semantic blocking and language switching was observed such that latencies were slowest in homogeneous context when switching into L1, but only for the Arabic-English bilinguals. This finding suggests that switching into L1 as compared to L2 is demanding in terms of lexical selection. In addition, the performance of Arabic bilinguals when switching into L1 under high lexical selection demands correlated with their response inhibition/selection ability, as measured by a Flanker task. This suggests that bilinguals’ ability to resolve lexical competition is related to their domain-general response selection ability. This correlation was not observed for the German-English bilinguals, suggesting that similar languages may interfere less with each other. However, the analysis of bilingual language profile highlighted a number of subtle differences between the two groups of bilinguals, which might have contributed to the difference in their results. Taken together, the findings from this thesis have theoretical consequences for accounts of bilingual lexical processing and for the relationship of bilingualism to non-linguistic cognition.