Similar Semantic Category Distributions but Distinct Noun Choices in Nonacademic Second Language Writing of Graduate Students With Different Disciplinary Backgrounds: A Natural Language Processing‐Based Analysis

The disciplinary background of second language (L2) writers can shape their writing style, including their lexical choices. This study examines lexical differences in nonacademic argumentative essays on the same topic by L2‐English graduate students with humanities‐related or science‐related majors. Using natural language processing (NLP) techniques, the study extracts nouns from these writers’ essays and classifies them into 21 semantic categories of the English UCREL Semantic Analysis System. Regression analyses show no significant difference in the distribution of the semantic categories between the two groups. However, a follow‐up keyness analysis reveals that their specific noun choices do differ significantly: The humanities students’ writing includes more nouns related to psychological and social ideas, while the science students’ writing utilizes more nouns referring to concrete objects. These findings suggest that even when L2 writers address a topic outside of their field, their disciplinary background plays a role in their noun choices, influencing how they express their ideas. The study's results also demonstrate the benefits of combining different analytical methods to examine the same data, with important implications for teaching and learning practices.