The influence of task type and learner language background on writing production and anxiety: A Bayesian linear mixed-effects analysis

Despite growing interest in task-based language teaching (TBLT), limited empirical work has examined how different rhetorical task types influence second language (L2) writing development, especially in relation to affective variables, such as writing anxiety. Existing research in TBLT has largely focused on cognitive dimensions, often neglecting individual differences in learners’ emotional responses. Moreover, Long’s (2014) call to use first language (L1) data as a benchmark in TBLT remains underexplored, complicating the interpretation of L2 performance patterns. To address these gaps, we examined the impact of task type and writing anxiety on the written performance of 140 university students (70 L1 English speakers, 70 L2 English learners). Participants completed a writing anxiety questionnaire and performed four rhetorical tasks over four weeks. Essays were assessed using syntactic complexity, accuracy, lexical complexity, and fluency (CALF) indices. Bayesian linear mixed-effects modeling was used to analyze both linguistic and affective variables. Results revealed significantly higher levels of somatic anxiety, cognitive anxiety, and anxiety avoidance among L2 writers. In both groups, increased task complexity was associated with longer clauses and more sophisticated syntax, with L1 writers showing steady gains in accuracy and fluency. L2 writers, however, exhibited greater variability: accuracy spiked during the argumentative task, while lexical diversity declined. The findings highlight the interaction between cognitive task demands and affective factors in shaping L2 writing outcomes, offering insights for TBLT researchers and pedagogical practices in L2 writing.