One view of critical period research that has had an important impact on the way we look at studies of language acquisition has been expressed in the work of Vivian Cook (2008). He makes a strong case for the inappropriateness of using the criterion of ‘ indistinguishable from a native speaker’ as the basis for success in second language acquisition. Indeed , Cook argues that a second language speakers because the real goal is ‘ multicompetence ’ , that is , knowledge of multiple languages that inform and enrich one another.
Research on the long-term outcomes of second language learning as well as the rate of learning at different ages brings us to a question that is probably of greatest interest to most readers of this book : What can we conclude about the role of age when learning takes place primarily in an educational setting ?