The effect of language proficiency on executive functions in balanced and unbalanced Spanish-English bilinguals

This study analyzed the association between levels of language proficiency and levels of bilingualism and performance on verbal and nonverbal executive functions (working memory, updating, shifting, and inhibition tasks) in young bilinguals. Forty balanced (high and low proficiency), 34 unbalanced bilinguals, and 40 English monolinguals, were selected. The Bilingual Verbal Ability Test was used as a measure of language proficiency; WAIS Block design test was used as a measure of non-verbal intelligence. High proficiency balanced bilinguals performed better than low proficiency balanced bilinguals; unbalanced bilinguals scored in between both balanced groups. High proficiency monolinguals scored higher than low proficiency monolinguals and similar to high proficiency bilinguals. Regression analyses demonstrated that nonverbal intelligence significantly predicted performances on verbal working memory and verbal and nonverbal inhibition tasks. It was concluded that nonverbal intelligence scores are better predictors of executive function performance than bilingualism or language proficiency.