Integrating metadiscourse analysis with transformer-based models for enhancing construct representation and discourse competence assessment in L2 writing: a systemic multidisciplinary approach

In recent years, large-scale language test providers have developed or adapted automated essay scoring systems (AESS) to score L2 writing essays. While the benefits of using AESS are clear, they are not without limitations, such as over-reliance on frequency counts of vocabulary and grammar variables. Discourse competence is one important aspect of L2 writing yet to be fully explored in AEE application. Evidence of discourse competence can be seen in the use of Metadiscourse Markers (MDM) to produce reader-friendly texts. The article presents a multidisciplinary study to explore the feasibility of expanding the construct representation of automated scoring models to assess discourse competence in L2 writing. Combining machine learning, automated textual analysis and corpus-linguistic methods to examine 2000 scripts across two tasks and five proficiency levels, the study investigates (1) in addition to frequency and range, whether accuracy of MDM is worth pursuing as a predictive feature in L2 writing, and (2) how identification and classification of MDM use might be fed into developing an automated scoring model using machine learning techniques. The contributions of this study are three-fold. Firstly, it offers valuable insights within the context of Explainable AI. By integrating MDM usage and accuracy into the scoring framework, this research moves beyond frequency-based evaluation. This study also makes significant contributions to the current understanding of L2 writing development that even lower-proficiency learners exhibit evidence of discourse competence through their accurate use of MDMs as well as their choice of MDMs in response to genre. From the perspective of expanding the construct representation in automated scoring systems, this study provides a critical examination of the limitations of many AEE models, which have heavily relied on vocabulary and grammar features. By exploring the feasibility of incorporating MDMs as predictive features, this research demonstrates the potential for construct expansion of L2 AEE. The results would support test providers in developing competence tests in various contexts and domains including manufacturing, medicine and so on.