A multi-metric analysis of 50,000 linguistic profiles provides sparse evidence that language distance modulates bilingual cognition

Similarity in mental, linguistic representations modulates the degree of recruitment of cognitive control mechanisms, which have been linked to neurocognitive adaptations in bilingual populations. While ample evidence exists for this claim, its coverage is limited, as testing is geared towards WEIRD communities that use sizeable, Indo-European languages, thus potentially providing a biased view of bilingual cognition. We assess the role of distance as a key moderator of bilingual adaptations through a large-scale aggregation analysis of 510 experiments. To measure distance, we develop a multi-metric approach, using state-of-the-art databases, such as Grambank. Analyzing data from 56,122 participants who speak 79 different languages, spanning 11 language families and a language isolate, we find sparse evidence for a distance effect. Our results suggest that moderators such as language distance can shed light on the cognitive divide between language and dialects in a way that addresses the perennial question of what makes bilinguals distinct.