Vocabulary matters! The relationship between verbal fluency and measures of inhibitory control in monolingual and bilingual children

The role of early bilingual experience in the development of skills in the general cognitive and linguistic domains remains poorly understood. This study investigated the link between these two domains by assessing inhibitory control processes in school-aged monolingual and bilingual children with similar English receptive vocabulary size. The participants, 8-year-old monolinguals and bilinguals, completed two Verbal Fluency Tasks (VFTs), letter and category, and two measures of inhibitory control. Results showed that bilinguals outperformed monolinguals on the VFTs, but performance was similar on the inhibitory control measures approaching ceiling for both monolingual and bilingual children. Importantly, it was shown that both vocabulary proficiency and general inhibitory control skills underlie monolingual and bilingual children's performance on VFTs. These results demonstrate that vocabulary proficiency plays a fundamental role in comparing monolingual and bilingual VFT performance. The bilingual advantage found in this study seems to have escaped previous studies that did not account for vocabulary size in populations of bilingual and monolingual school-aged children. (C) 2018 Elsevier Inc. All rights reserved.