Cognates, competition and control in bilingual speech production

Abstract

If an individual speaks more than one language, there are always at least two ways of verbalising any thought to be expressed. The bilingual speaker must then have a means of ensuring that their utterances are produced in the desired language. However, prominent models of speech production are based almost exclusively on monolingual considerations and require substantial modification to account for bilingual production. A particularly important feature to be explained is the way bilinguals control the language of speech production: for instance, preventing interference from the unintended language, and switching from one language to another. One recent model draws a parallel between bilinguals control of their linguistic system and the control of cognitive tasks more generally. The first two experiments reported in this thesis explore the validity of this model by comparing bilingual language switching with a monolingual switching task, as well as to the broader task-switching literature. Switch costs did not conform to the predictions of the task-set inhibition hypothesis in either experiment, as the paradoxical asymmetry of switch costs was not replicated and some conditions showed benefits, rather than costs, for switching between languages or tasks. Further experiments combined picture naming with negative priming and semantic competitor priming paradigms to examine the role of inhibitory and competitive processes in bilingual lexical selection. Each experiment was also conducted in a parallel monolingual version. Very little negative priming was evident when speaking the second language, but the effects of interlingual cognate status were pronounced. There were some indications of cross-language competition at the level of lexical selection: participants appeared unable to suppress the irrelevant language, even when doing so would make the task easier. Across all the experiments, there was no evidence for global inhibition of the language-not-in-use during speech production. Overall results were characterised by a remarkable flexibility in the mechanisms of bilingual control. A striking dissociation emerged between the patterns of results for cognate and non-cognate items, which was reflected throughout the series of experiments and implicates qualitative differences in the way these lexical items are represented and interconnected.