In a meta-study of 152 studies in six executive domains, Minna Lehtonen and her colleagues have looked for the assumed positive effect of bilingualism on executive functions compared with monolinguals – and have found none.
The study “Is bilingualism associated with enhanced executive functioning in adults? A meta-analytic review” – published in the Psychological Bulletin of the American Psychological Association – found that marginal advantages for inhibition, shifting, and working memory disappeared after correction for bias and no advantages were found for monitoring or attention. For verbal fluency, they found a small disadvantage. They conclude that the available evidence does not provide systematic support for the widely held notion that bilingualism is associated with benefits in cognitive control functions in adults.