Bridging the usability gap in ESP: enhancing engagement and lexical competence through digital corpus-based instruction

Despite the proven efficacy of corpus linguistics in language education, its adoption in English for Specific Purposes (ESP) classrooms remains limited due to the technical complexity of corpus tools, particularly in non-English departments. Addressing this “usability gap,” this study evaluates the effectiveness of the Digital Corpus-based Instruction (DCI) model, a novel instructional framework that synergizes corpus data, QR-code technology, and Mobile-Assisted Language Learning (MALL). The study aims to determine if providing corpus data through familiar mobile interfaces can improve lexical competence among non-English majors in low-resource settings. Employing a quasi-experimental design with a convergent parallel mixed-methods approach, the study involved 30 non-English-major undergraduates in an Indonesian university setting. Quantitative data from standardized pre- and post-tests, focusing on vocabulary matching, collocation awareness, reading, and professional writing, were triangulated with qualitative insights from classroom observations, Focus Group Discussions (FGDs), and interviews to capture behavioral and cognitive shifts. The results revealed a statistically significant improvement in the experimental group ( p < 0.001), with a very large effect size (Cohen's d > 1.93). Significant gains were observed in collocation awareness (from 2.30 to 5.13) and professional writing accuracy (from 7.83 to 10.10). Qualitative findings corroborated these metrics, indicating a pedagogical transformation from passive learning to active, data-driven inquiry and increased professional confidence. This study contributes to the field by demonstrating that DCI effectively reduces the cognitive load of corpus analysis, offering a scalable, pedagogically viable solution for enhancing ESP competence in higher education contexts.