Brain potentials reveal discrete stages of L2 grammatical learning

In this article we review several studies investigating the neural correlates of second-language (L2) grammatical learning in the context of novice adult learners progressing through their first year of L2 classroom instruction. The primary goal of these studies was to determine how and when learners incorporate L2 knowledge into their online language processing system. We show that at least some learners progress through discrete stages of grammatical learning during the first year of instruction. These stages are robust across languages, experimental tasks, and levels of language (lexical vs. sentential) and indicate that there is an intermediate stage of learning between no L2 grammatical knowledge and grammaticalization. We also show that although learners' brain responses are quite variable, this variability is highly systematic and can be used to identify meaningful subgroups of learners.