Lexical richness in young English learners’ writing: A focus on opinion and listen-write task types

Ample research has examined the linguistic characteristics of second language (L2) writing across proficiency scores, with a focus on lexical diversity, sophistication, and density as key dimensions of lexical richness. However, the applicability of these indices to young L2 learners’ writings, often characterized by limited vocabulary and constrained output in standardized writing tasks, remained underexplored. To address this gap, this study analyzed the lexical richness of young L2 learners’ written productions from two TOEFL Junior Writing tasks (Opinion and Listen-Write tasks), using 37 tailored indices of lexical diversity, sophistication, and density. The results indicated that the lexical characteristics of young L2 learners vary by task score and task type, particularly when assessed through indices such as lexical diversity (e.g., moving-average type-token ratio) and sophistication (e.g., n-gram strength of association). Nonetheless, incorporating additional measures, such as syntactic complexity or discourse features, may be essential for distinguishing young L2 learners at higher proficiency levels.