When Do Children Lose the Language Instinct? A Critical Review of the Critical Periods Literature

While it is clear that children are more successful at learning language than adults are—whether first language or second—there is no agreement as to why. Is it due to greater neural plasticity, greater motivation, more ample opportunity for learning, superior cognitive function, lack of interference from a first language, or something else? A difficulty in teasing apart these theories is that while they make different empirical predictions, there are few unambiguous facts against which to test the theories. This is particularly true when it comes to the most basic questions about the phenomenon: When does the childhood advantage dissipate, and how rapidly does it do so? I argue that a major reason for the lack of consensus is limitations in the research methods used to date. I conclude by discussing a recently emerging methodology and by making suggestions about the path forward. Expected final online publication date for the Annual Review of Linguistics, Volume 8 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.