The Myth of the Critical Period

In language conferences, student papers, some linguistics textbooks, and wider culture, the critical period hypothesis is presented as factual despite still being fiercely debated in academic literature. The widespread popular acceptance of the hypothesis contrasts with a sharp debate and criticism of it in academic literature (Muñoz & Singleton, 2011; Ortega, 2009). This article considers the basis of the hypothesis, a concept from biology that describes a species-wide acquisition window for a trait that affects every member of the species and ends in a relatively abrupt manner (Knudson, 2004). After a critical period passes, a member of the affected species has little or no hope of acquiring a trait, as if the window were permanently sealed. The article then discusses the evidence for and against the hypothesis from additional and native language acquisition, ultimately concluding that evidence best supports a sensitive period within the first 2 years of life (Muñoz & Singleton, 2011). Discussion then turns to what factors determine success in language learning, with consideration of how teachers can best support their students of all ages and how to change popular acceptance of the hypothesis and its inhibition of language learning.