Because of enduring experience of managing two languages, bilinguals
have been argued to develop superior executive functioning compared with
monolinguals. Despite extensive investigation, there is, however, no
consensus regarding the existence of such a bilingual advantage. Here we
synthesized comparisons of bilinguals’ and monolinguals’ performance in
six executive domains using 891 effect sizes from 152 studies on
adults. We also included unpublished data, and considered the potential
influence of a number of study-, task-, and participant-related
variables. Before correcting estimates for observed publication bias,
our analyses revealed a very small bilingual advantage for inhibition,
shifting, and working memory, but not for monitoring or attention. No
evidence for a bilingual advantage remained after correcting for bias.
For verbal fluency, our analyses indicated a small bilingual
disadvantage, possibly reflecting less exposure for each individual
language when using two languages in a balanced manner. Moreover,
moderator analyses did not support theoretical presuppositions
concerning the bilingual advantage. We 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.