Abstract
Recent studies suggest that cognateness boosts bilingual lexical acquisition. This study proposes an account in which language co-activation accelerates accumulation of word-learning instances across languages. This account predicts a larger cognate facilitation for words in the lower-exposure language than in the higher-exposure language, as the former receive co-activation from their translations more frequently. Bayesian Item Response Theory was used to model acquisition trajectories for 604 Catalan-Spanish translations from a dataset of 366 12-32 month-old bilinguals (M = 22.23 months, 175 female, mainly White, collected 2020-2022). Results show a larger cognate facilitation for words in the lower-exposure language (d = .276), than for words in the higher-exposure language (d = .022), supporting a language exposure-moderated account for the effect of cognateness on lexical acquisition.