The effects of language proficiency and task type on executive function and working memory performance in bilingual adults

Research shows that bilingualism confers substantial cognitive benefits in children and the elderly. Bilingual advantages on nonverbal working memory, updating, shifting and inhibition tasks are widely reported. However, advantages are not always observed in young adults. These disparities may be due to varied proficiency levels and task types (verbal versus nonverbal) administered. This study sought to detect bilingual performance advantages on executive function and working memory tasks (verbal and nonverbal working memory, updating, shifting and inhibition tasks) between groups of 37 high and 37 low proficiency Spanish-English bilingual and 40 English monolingual young adults. Mixed MANCOVAs, using nonverbal intelligence scores as a covariate, identified no significant differences between language groups for performance on any task type or cognitive domain tested. Regression analyses showed nonverbal intelligence underlay performance on five of eight tasks. Young adulthood may represent a lull during which bilingualism does not confer cognitive advantages for functions examined.