Task complexity and repetition effects on sense-aware lexical sophistication: An extension of Abdi Tabari et al.’s (2025) study on L1 and L2 learners

Abstract Prior research in task-based language teaching (TBLT) has examined the individual effects of Task Complexity (TC) and Task Repetition (TR) on second language (L2) written production. However, investigations into the combined influence of TR and TC on L2 written production remain scarce. Additionally, there is a dearth of TBLT studies that employ newly emerged sense-aware lexical sophistication indices in first language (L1) and L2 English writing. To bridge these research gaps, this study compared the effects of TC, TR, and their interplay on traditional word-form-based and sense-aware frequency-based indices of lexical sophistication in both L1 and L2 writing. Fifty L1 and 50 L2 writers each completed simple and complex versions of an argumentative writing task twice. The L1 and L2 essays were analyzed using three traditional and three sense-aware frequency-based indices of lexical sophistication. Linear mixed-effects models showed that TC and TR positively affected the proportion of sophisticated types and tokens in terms of both word forms and word senses, and TC also negatively affected the mean logarithmic frequency of tokens in terms of both word forms and word senses. The possible mechanisms underlying the effects observed are discussed.