Verb-centric or balanced?: An NLP-based assessment of word class contributions to L2 writing proficiency

Abstract

Despite the significant role of verbs in second language (L2) development, few studies have explicitly tested the comparative role of verbs in predicting L2 writing proficiency compared to other lexical categories, such as adjectives, adverbs, and nouns. Motivated by the theoretical and linguistic prominence of verbs, this study examines whether verbs serve as stronger predictors of L2 writing proficiency than other word classes. Our category-based analysis of lexical diversity and sophistication features in argumentative essays showed that verbs play a distinct and prominent role in L2 writing, outperforming other lexical categories as predictors of L2 proficiency. Specifically, higher-proficiency argumentative essays were found to exhibit a greater variety of verbs that are infrequent, academically oriented, less familiar, and acquired later in language development. At theoretical level, our findings align with the perspectives emphasizing the crucial role of verbs in language development. Pedagogically, our findings highlight the need for category-based vocabulary instruction in L2 writing classes.