How task types shape lexical sophistication in L2 learner writing

Abstract This study examined the effects of writing task type on lexical sophistication in second language (L2) writing. A total of 70 English as a Second Language (ESL) learners at a large US university completed four writing tasks (descriptive, narrative, expository, and argumentative), producing 280 writing samples as part of their curriculum. The texts were analyzed using lexical sophistication indices capturing word- and n-gram-based frequency and range, psycholinguistic properties, and semantic relations. Results showed that academic words were more frequent in argumentative and narrative writing than in descriptive and expository tasks, whereas the range of academic words, bigrams, and trigrams was higher in expository and narrative texts. Argumentative essays used words with lower familiarity, imageability, and meaningfulness values, reflecting less common and less associatively rich vocabulary. Descriptive and narrative essays showed higher polysemy values than argumentative and expository texts. Overall, task type produced selective effects across dimensions of lexical sophistication, highlighting implications for L2 writing research and pedagogy.