From the laboratory to the classroom: Rethinking ERP methods in second language acquisition.

Event-related potentials (ERPs) are widely used to study second language acquisition. However, ERP research has largely remained confined to laboratory paradigms and has had limited impact on second language teaching and assessment. A case in point are early studies which have shown that language instruction can shape neural responses, yet this line of work has not been developed or applied further. Current ERP studies often rely on loosely defined constructs such as instruction and proficiency, frequently operationalized through task-internal measures that overlap with the linguistic features under investigation. This limits interpretability and relevance for real-world learning and application. In this article, we aim to advance a conceptual and methodological agenda for reorienting ERP research in instructed second language acquisition. We argue that ERP research should engage more directly with language teaching and assessment by adopting independent, communicatively grounded measures of proficiency. Materials adapted from standardized proficiency examinations (e.g., CEFR-based tests) could provide experimental stimuli while anchoring proficiency to externally defined constructs of communicative competence. This approach could reduce circularity, strengthen the ecological validity of ERP research, and foster mutual validation between neurolinguistics, language assessment, and second language teaching.