The Brain Mechanisms Underlying the Cognitive Benefits of Bilingualism may be Extraordinarily Difficult to Discover

The hypothesis that coordinating two or more languages leads to an enhancement in executive functioning has been intensely studied for the past decade with very mixed results. The purpose of this review and analysis is to consider why it has been (and will continue to be) difficult to discover the brain mechanisms underlying any cognitive benefits to bilingualism. Six reasons are discussed: 1) the phenomenon may not actually exist; 2) the cognitive neuroscientists investigating bilingual advantages may have been studying the wrong component of executive functioning; 3) most experiments use risky small numbers of participants and are underpowered; 4) the neural differences between groups do not align with the behavioral differences; 5) neural differences sometimes suffer from valence ambiguity, that is, disagreements whether “more” implies better or worse functioning and 6) neural differences often suffer from kind ambiguity, that is, disagreements regarding what type of mental events the pattern of activation in a region-of-interest actually reflects.