Effects of Task Complexity and L2 Proficiency on Functional Adequacy in L2 Writing

This study examined how task complexity and second language (L2) proficiency impact functional adequacy (FA) among Chinese university English learners. Eighty-nine Chinese undergraduate students from two first-year and two third-year classes participated in the study. Each participant completed two timed argumentative writing tasks with varying degrees of task complexity manipulated by altering the number of argument elements and reasoning demands, drawing upon the cognition hypothesis. The task-complexity manipulations were validated by post-task questionnaires and expert judgments. Learners’ productions were assessed by two experts using the FA rating scale. Results showed as task complexity increased, there was a significant decrease in scores across all four dimensions of FA. Additionally, a positive effect of L2 proficiency was observed on scores in two dimensions of FA, that is, comprehensibility and coherence and cohesion. However, this was not the case for content and task requirements. Importantly, the analysis revealed a significant interaction effect between task complexity and L2 proficiency, indicating that the impact of task complexity on FA varied depending on the learners’ proficiency levels. Specifically, higher proficiency learners demonstrated greater adaptability to complex tasks compared to their lower proficiency counterparts. These findings highlight the significance of manipulating task complexity and considering learners’ L2 proficiency in teaching L2 writing to enhance learners’ FA performance.