ABSTRACT
There is a growing recognition that individual differences (IDs) are ubiquitous across the lifespan both in first and second language acquisition. Language acquisition is conceived of as learning how to process linguistic input efficiently. Two components of language aptitude – i.e. inductive ability and grammatical sensitivity – turned out to be most strongly associated with the complexity and accuracy of second language (L2) performance. Adopting a Complex Dynamic System perspective, several learner corpus studies have shown that different aspects of L2 knowledge develop at different rates and that learners develop through individually owned trajectories. Learner Corpus Research is a valuable complement to the growing body of ID research situated within emergentist accounts that view production data as a key data type. The chapter addresses methodological issues related to the study of individual trajectories in L2 development. Learner corpora are particularly suitable to capture the complex, dynamic, and nonlinear process of L2 development.
