ABSTRACT
This chapter begins with the work of neuro- and psycholinguists who investigate the memory systems that underpin learning, and use this research to explain differences between first language (L1) and second language (L2) learning, and between L1 and L2 online processing, and differences in learning trajectories between different learners. The existence of different memory systems is supported by a long research tradition in cognitive psychology, and over the last 30 years these ideas have been applied to L2 theories to explain differences in learning speed and success at different ages. L2 researchers who are interested in the role of explicit knowledge and practice in L2 learning are, essentially, appealing to Skill Acquisition Theory. Skill Acquisition Theory predicts clear advantages for instructed learners, as they are more likely to have regular access to accurate and generalizable declarative knowledge and opportunities for practice.
