Individual Differences In Bilingual Experience Modulate Executive Control Network And Performance: Behavioral And Structural Neuroimaging Evidence

Abstract

Dual/multiple language use has been suggested to affect human cognition and neural substrates. Nevertheless, considerable variability emerges concerning replicability of such effects, likely originating in the common practice of reducing the spectrum of bilingualism to a dichotomy of presence vs. absence (i.e., bi- vs. monolingualism), thus diluting the role of interindividual variability in bilingual experience in modulating neuroplastic and cognitive changes. To address this, we operationalized the main bilingual experience factors as continuous variables, investigating their effects on executive control (EC) performance and neural substrate deploying a Flanker task and structural MRI. Higher L2 proficiency predicted better executive performance. Moreover, neuroimaging results indicated that bilingualism-related neuroplasticity may peak at a certain stage of bilingual experience and eventually revert, possibly following functional specialization. Indeed, experienced bilinguals optimized behavioral performance independently of volumetric variations in executive areas. We conclude that individual differences in bilingual experience modulate bilingualism’s cognitive and neural consequences.