Effects of Working Memory and Proficiency on Lexical Complexity in L2 Writing: A Case of Two Task Types

Abstract

This study focuses on the potential relationship between working memory and lexical complexity and the moderating effect of proficiency on this relationship across two task types. One hundred and forty-eight Chinese college students completed integrated and independent writing tasks from the test of English as a foreign language (TOEFL) iBT. Natural language processing tools were used to measure lexical complexity (lexical diversity, sophistication, and density). Participants also completed a working memory test and had their English proficiency assessed using the Band 6 College English Test (CET-6). On the integrated task, working memory was not significantly correlated with any measures of lexical complexity. However, proficiency moderated the relationship between working memory and one measure of lexical sophistication. On the independent task, weak but statistically significant correlations emerged between working memory and three measures of lexical sophistication. No moderation effects were observed on the independent task. These findings suggest that the role of working memory in second language (L2) lexical complexity may be task-dependent, offering tentative insights that could inform the teaching of L2 writing.