Bilingualism affects infant cognition: Insights from new and open data

Bilingualism has been hypothesized to shape cognitive abilities across the lifespan. Here, we examined the replicability of a seminal study that showed monolingual–bilingual differences in infancy (Kovács & Mehler, 2009a) by collecting new data from 7-month-olds and 20-month-olds and reanalyzing three open datasets from 7–9 month-olds (D’Souza et al., 2020; Kalashikova et al., 2020; 2021). Infants from all studies (N = 222) were tested in an anticipatory eye-tracking paradigm, where they learned to use a cue to anticipate a reward presented on one side of a screen during Training, and the opposite side at Test. To correctly anticipate the reward at Test, infants had to update their previously learned behavior. Across 4 out of 5 studies, a fine-grained analysis of infants’ anticipations showed that bilinguals were better able to update the previously-learned response at Test, which could be related to bilinguals’ weaker initial learning during Training. However, in one study of 7-month-olds, we observed the opposite pattern: bilinguals performed better during Training, and monolinguals performed better at Test. These results show that bilingualism affects how infants process information during learning. We also highlight the potential of open science to advance our understanding of language development.