Enhancing advanced vocabulary in EFL writing: an AI-assisted intervention for English studies students in Poland

Abstract Effective use of advanced vocabulary is crucial for higher-level English language learners, particularly as they progress towards C1 proficiency according to the Common European Framework of Reference for Languages (CEFR). However, incorporating sufficiently sophisticated vocabulary in writing remains challenging for many learners. This quasi-experimental study investigated the effectiveness of an AI-assisted intervention designed to enhance awareness and use of advanced vocabulary among B2 level first-year English Studies students in Poland ( n = 71). The intervention, integrated into regular coursework over five sessions, included exposure to advanced vocabulary through reading, explicit instruction on word proficiency levels, and opportunities for vocabulary use in writing. Data were collected through summary writing and word recognition tasks. The CEFR checker, an AI-based text analyser, was employed to identify C1+ and B2 level vocabulary in students’ writing. Results revealed modest but noticeable improvements in both the use and recognition of C1+ and B2 level vocabulary over time. The study also found changing correlations between vocabulary use and recognition across sessions, particularly for C1+ words. These findings highlight the potential of AI-assisted instruction in enhancing advanced vocabulary among higher proficiency EFL learners. The study contributes to the growing body of CALL literature on AI-assisted L2 instruction and opens avenues for further research on new pedagogical approaches to facilitate advanced vocabulary development in EFL writing.