A longitudinal study on lexical accessibility and executive control in adult bilinguals

In recent decades, much research has explored the relationship between the bilingual experience, language switching, executive control mechanisms, and various external factors. The current study contributes to this literature by providing a comprehensive account of different factors that may impact language switching and executive control performance. Specifically, it aims to gain an understanding of the changes to language control and executive control changes in the first stages of immersion in an L2 environment and the interrelationship between language control and executive control while controlling for influences of language use. The performance of 30 young adult Chinese-English bilinguals in a dual-language picture naming task, two executive control tasks (Simon, Flankers) and responses on an activity log questionnaire were investigated over six months upon initial immersion in the English L2 environment. The performance of 20 functionally monolingual English speakers with no L2 immersion background on the three reaction-time-based tasks were used as a proxy baseline measure against which to investigate the bilinguals’ response times. This approach allowed us to comprehensively portray lexical accessibility and the development of both language control and executive control in the initial stages of L2 immersion to understand better the interplay of the different factors upon each other across the course of development. The synthesis of the results painted a convoluted picture, suggesting that the development of lexical access and executive control is not as straightforward as previously assumed: for instance, our results did not support the bilingual advantage hypothesis, as bilinguals surpassed the functionally monolingual speakers only in measures of the Flanker task performance. Interestingly, participants who were more balanced across languages performed better in the executive control tasks as opposed to participants who were more dominant in Chinese. Several factors of language use influenced both lexical access and executive control, including using L2 in academic settings and social contexts.