The Cognitive and Neural Bases of Bilingual Word Selection
Hughes, Julie Walker
Schnur, Tatiana T
Doctor of Philosophy
When bilinguals speak, do words from both languages compete for selection? Under one hypothesis of bilingual word selection, bilinguals select words for speech similarly to monolinguals because word selection is restricted to the response language (language specific selection; e.g., Costa & Caramazza, 1999). Alternatively, bilinguals may select words for speech such that words from both languages are considered during selection (language non-specific selection; e.g., Green, 1998). Critically, if bilinguals choose words from among both the response and non-response languages, then they must manage the activation levels of two competing languages in order to select the correct word. It is assumed that bilinguals accomplish this process by exerting inhibitory control over non-response language words to reduce their activation level (e.g., Meuter & Allport, 1999), which may grant bilinguals an inhibitory control advantage in comparison to monolinguals because bilinguals constantly recruit and exercise inhibitory control processes (e.g., Bialystok, Craik & Luk, 2012). However, it remains an open question whether bilingual word selection proceeds differently from that of monolinguals. Thus, the main goal of this dissertation was to characterize bilingual word selection during speech. Specifically, I manipulated a factor known to influence word selection processes (i.e., whether a picture has more than one name or not (name agreement (NA)), e.g., sofa/couch; e.g., Vitkovitch & Humphreys, 1995) to determine how bilinguals select words for speech. I investigated bilingual word selection by comparing bilingual and monolingual speakers’ behavioral performance and neural activation patterns on a picture naming task that manipulated response and non-response language NA. The results show that bilinguals’ behavioral performance and level of neural activation are not influenced by non-response language NA. However, bilinguals did show neural connectivity patterns that were influenced by non-response language NA. I interpreted this pattern of results to suggest that bilinguals select words from both languages and that they use inhibitory control processes to do so. The results thus not only characterize how bilinguals produce words fluently in one language over another but also shed light on the potential link between bilingual word selection processes and the possible cognitive advantages associated with bilingualism.
Bilingualism; Word Selection; Cognitive Control; fMRI