Theories of bilingual advantage in executive functioning are too vague and thus difficult to falsify

What is it about?

Since the publication of the seminal work by Bialystok et al. (2004), the argument of bilingualism enhancing executive functioning (EF) has attracted the attention of both expert and nonexpert audiences. Yet, the paper by Paap et al. (2015) calls into question many different research findings taken as evidence for a bilingual advantage in EF. Paap et al. highlight the inconsistency of findings regarding the specific EF component that should be affected by bilingualism and the particular aspect of bilinguals' experiences that should enhance the efficiency of such a component. This is related to what is, in their opinion, one of the most serious faults of the literature on this topic, that is, the lack of a clear, sound, well-grounded and broadly endorsed theory about how the mechanisms responsible for the management of the two languages would affect executive functions. The advocates of the bilingual advantage in EF assume that the bilinguals' massive practice in inhibiting one language when they speak the other and in switching among languages would improve domain-general executive processes. They took for granted the existence of some relationship between the mechanisms that allow a person to handle two languages and those underlying the selection and control of other types of processes. However, the exact nature of this relation is usually not well specified and it is actually far from being clear. A detailed, comprehensive and substantiated theory of the mechanisms underlying bilingualism and of their links with other cognitive processes would allow one to make precise hypotheses regarding the pattern of results we should expect in a given task, tapping a certain ability, and to predict the performance of which particular group of bilinguals should differ from that of monolinguals. As revealed by Paap et al. (2015)’s overview, the picture of data concerning these critical points is quite confused and difficult to interpret. Different and sometimes opposite findings are interpreted as the result of bilinguals' greater efficiency of the same EF component. Here we discuss the case of findings concerning neuroanatomical differences between bilinguals and monolinguals (specifically differences in the structure of white matter tracts).

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