Diachronic variations of metadiscourse markers in research articles

Metadiscourse markers (MDMs) are rhetorical devices used to enhance audience comprehension (interactive MDMs) and engage authors and audiences within a text (interactional MDMs). This study examines diachronic variation in the use of interactive and interactional MDMs across 240 research articles (RAs) from soft-pure (English literature), soft-applied (applied linguistics), hard-applied (pharmacology), and hard-pure (mathematics) disciplines, published in two periods (1994–1998 and 2019–2023). Using descriptive and inferential statistics, along with commentary on corpus excerpts, the results revealed distinct patterns of diachronic changes in MDM use, confirming temporal and disciplinary variations. Based on the findings, the study provides recommendations for English for academic purposes (EAP) and reading and writing courses. Additionally, suggestions for future research on this underexplored variation are offered. • MDM increased in the 2019–2023 RAs in comparison to the 1994–1998 RAs. • Interactive markers increased in soft-applied RAs. • Interactive markers increased in hard-applied and hard-pure RAs. • Interactional markers increased in soft-pure and soft-applied RAs. • Interactional markers increased in hard-applied RAs.