• usage-based approach
• critical period
• brain plasticity
• construction grammar
• first language acquisition
• multilingualism

Through the analysis of neuroplasticity and critical periods for language acquisition, brain malleability as a result of linguistically-enriched environments, i.e. bilingual and multilingual settings, is explored. Furthermore, the two major approaches in first language acquisition, the nativist approach and the usage-based, constructionist approach are investigated and a case is made that native languages are acquired through the processes of statistical learning combined with cognitive abilities, social skills, a tendency to imitate and vast linguistic input from mothers to their children. Furthermore, diary studies involving the author and her bilingual children are presented, negative transfer due to crosslinguistic influence is investigated and bilingual error fossilization due to sibling influence is hypothesized. Moreover, metalinguistic awareness of divergent constructions in English and Italian is investigated through an acceptability test administered to twenty-one Italian/English, elementary school-aged children during the critical period for language acquisition.