Does the relationship between executive functions and L2 writing depend on language proficiency?

Executive functions are attributed a central role in maintaining fluency during L2 text composition, allowing writers to orchestrate the various linguistic and cognitive processes and resources involved in writing. The study examined (1) whether language proficiency moderates the relationship between executive functions and writing fluency in L2 writing and (2) whether the effects indirectly affect text quality. Sixty university students composed two texts in English as their L2, an argumentation and a description, three executive function tasks assessing inhibition, shifting, and updating skills, a language proficiency test, and a copy task. Keystroke logging protocols were recorded with Inputlog and analyzed for writing fluency. Text quality was assessed with a holistic benchmark procedure and comparative judgments. The results revealed language-dependent and genre-specific effects of updating and shifting but not inhibition skills on writing fluency. Path models indicated that the interactions between executive functions and language proficiency indirectly affect text quality through process-related writing measures. The findings suggest a complex relation between executive functions and writing performance that depends on language proficiency and varies with task demands.