Rethinking the critical period for language: New insights into an old question from American Sign Language

• Published in: Bilingualism (Cambridge, England) Vol. 21; no. 5; pp. 886 - 905
• Main Authors: MAYBERRY, RACHEL I., KLUENDER, ROBERT
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.11.2018
• Subjects: Age of acquisition; American Sign Language; Brain; Brain research; Children; Critical period hypothesis; Deafness; Early second language learning; Educational Policy; Hearing loss; Keynote Article; Language acquisition; Language proficiency; Longitudinal studies; Neurolinguistics; Psycholinguistics; Scaffolding; Young Children; sign language; second language acquisition; neurolinguistic processing; critical period for language; first language acquisition
• ISSN: 1366-7289; 1469-1841
• DOI: 10.1017/S1366728917000724

The hypothesis that children surpass adults in long-term second-language proficiency is accepted as evidence for a critical period for language. However, the scope and nature of a critical period for language has been the subject of considerable debate. The controversy centers on whether the age-related decline in ultimate second-language proficiency is evidence for a critical period or something else. Here we argue that age-onset effects for first vs. second language outcome are largely different. We show this by examining psycholinguistic studies of ultimate attainment in L2 vs. L1 learners, longitudinal studies of adolescent L1 acquisition, and neurolinguistic studies of late L2 and L1 learners. This research indicates that L1 acquisition arises from post-natal brain development interacting with environmental linguistic experience. By contrast, L2 learning after early childhood is scaffolded by prior childhood L1 acquisition, both linguistically and neurally, making it a less clear test of the critical period for language.