Cognitive science has developed a number of experimental techniques for studying how people learn about sequentially structured stimulus material. We describe these techniques, review findings they have produced, and discuss the findings' relevance for understanding the mastery of syntax during second language learning. Three issues are addressed: (a) the nature or content of what is learned and how it might be represented in the language learner's knowledge base, paying special heed to acquiring abstract rules versus generalizing across stored examples, (b) the role of conscious awareness in syntactic learning, and (c) the role of limited-capacity processing or focal attention in syntactic learning. Care is taken to distinguish between the latter two factors—Focal attention to the task of learning about syntax and conscious awareness of particular syntactic structures are not the same thing and may well play different roles in successful acquisition.

This paper argues that the brain is the seat of cognition, that cognitive processes are neural processes, and that, in the brain, affect and cognition are distinguishable but inseparable. This perspective allows a reconceptualization of the affective filter in terms of the brain's stimulus appraisal system, which interacts with cognition to promote or inhibit second language acquisition. A research strategy is proposed for investigating these ideas.