Language use affects proficiency in Italian-Spanish bilinguals irrespective of age of second language acquisition.

The role of age of acquisition (AoA) in reaching native-like proficiency in second language is controversial. The existence of a critical period and the effect of AoA have been questioned by studies testing lexical and/or morphosyntactic skills, and by functional brain exploration. The aim of this study was to verify the effect of AoA and language practice on proficiency in a bilingual pragmatic task and its relationship with cognitive skills. The study involved a group of Italian-Spanish bilinguals, classified according to their AoA and language use. All participants performed a pragmatic bilingual test and a battery of cognitive tests. A multivariate analysis showed significant effects of language use and cognitive skills and a non-significant effect of AoA. These results indicate that continued language practice is a major factor influencing high bilingual proficiency, irrespective of AoA, suggesting that proficiency may be weakened when bilingual experience becomes occasional or ceases.