Executive Functions’ Impact on Vocabulary and Verbal Fluency among Mono- and Bilingual Preschool-Aged Children

BACKGROUND: The phenomenon of multilingualism and its impact on child development are in the spotlight of latter-day psychology, and of utmost importance both for theory and practice. Language development is a strong predictor of psychological readiness for school and further academic success. At the same time, children’s mastery of written and oral speech in school education in a multilingual environment has several distinctive features. This study was dedicated to examining the influence of executive functions on the development of the vocabulary aspects of speech (both active and passive vocabulary) of mono- and bilingual children growing up in a bilingual environment. OBJECTIVE: We aimed to analyze the relationship between bilingualism and language development (vocabulary and verbal fluency) and determine which executive functions may help overcome the resulting difficulties at preschool age. DESIGN: Both monolingual and bilingual children participated in the study (n = 137 and n = 81, respectively). The children’s ages ranged from 6 to 7 years (M = 78.7 months, SD = 5.87). Two independent General Linear Models (GLM) were built to define which executive functions influenced the vocabulary and verbal fluency of the mono- and bilingual subjects (controlling for age, gender, and non-verbal intelligence as well). RESULTS: The results confirmed that bilingualism is negatively related to language development, but showed that verbal working memory significantly helps bilinguals compensate for difficulties in developing vocabulary and verbal fluency. CONCLUSION: The study demonstrated that the ability to preserve and reproduce verbal information was of more significance for children’s vocabulary and verbal fluency than their language group (mono- or bilingual).