ABSTRACT
Many people believe that learning a second language (L2) is fundamentally different from learning a first language (L1). Evidence of this fundamental difference comes from the fact that first language acquisition almost invariably produces full native speaker competence, whereas many second language learners achieve only partial success in learning their new language. Some researchers believe that this difference in levels of ultimate attainment result arises because, after the expiration of a certain critical period, the learning mechanisms that subserve first language learning atrophy or expire.
