The potential roles of multilingualism and language structural distance in neurocognitive adaptation to language experience

A growing body of research shows that individual differences in bilingual language experience variably contribute to neurocognitive adaptations. The trends in this work are beginning to show a specificity of adaptations to the nature and degree of bilingual experiences – for example, duration of use, language switching, context and intensity of engagement. However, several other factors likely further influence these bilingualism-induced neural and cognitive adaptations. Two such factors may play a modulatory role but are currently under-researched in this field. The first is how such adaptations are affected by the addition of a third or more language and the second is the role of language structural distance in shaping neurocognitive adaptation trajectories. Regarding the role of multilingualism, previous research suggests differences in neurocognitive adaptation to multiple languages over two, although results are mixed. It is possible that, like bilingualism, individual differences in engagement with a third (or more) language might also variably condition neurocognitive adaptation, but this remains an unanswered empirical question. Regarding the role of language structural distance, there are plausible reasons to predict that the relative distance in language pairings would condition the nature or trajectory of bilingualism-induced adaptations, but this is also an understudied topic. I review the existing literature covering these factors, discuss the potential mechanisms of adaptation to each and propose some potential ways of incorporating these factors into future research.