Introduction

One of the biggest conundrums in linguistics centres around the notion of a critical period of language acquisition. The best empirical method to test the malleability of individual’s linguistic choices across their lifespan are panel studies, which take repeated samples from the same speakers at different points in chronological time. Moreover, while the literature suggests that many speakers do indeed remain constant after childhood or adolescence, the past two decades have produced a growing body of evidence that post-critical age speakers can and do indeed change some aspects of their native language. Empirically focused linguists, such as variationists, developmental and cognitive linguists, consider such changes in adult linguistic habits as evidence that supports a “life course perspective over a strict maturational explanation”. The chapter also presents an overview of the key concepts discussed in this book.