Proficiency and control in verbal fluency performance across the lifespan for monolinguals and bilinguals

Abstract

The verbal fluency task is a widely used neuropsychological test of word retrieval efficiency. Both category fluency (e.g., list animals) and letter fluency (e.g., list words that begin with F) place demands on semantic memory and executive control functions. However, letter fluency places greater demands on executive control than on category fluency, making this task well suited to investigating potential bilingual advantages in word retrieval. Here we report analyses on the category and letter fluency for bilinguals and monolinguals at four ages, namely, 7-year-olds, 10-year-olds, young adults and older adults. Three main findings emerged: (1) verbal fluency performance improved from childhood to young adulthood and remained relatively stable in late adulthood; (2) beginning at 10-year-olds, the executive control requirements for letter fluency were less effortful for bilinguals than monolinguals, with a robust bilingual advantage on this task emerging in adulthood and (3) an interaction among factors showed that category fluency performance was influenced by both age and vocabulary knowledge, but letter fluency performance was influenced by bilingual status.