This paper systematically explores the complex interactive effects among writer individual differences (WIDs) of second language (L2) learners and their impacts on writing performance, providing an important theoretical framework and empirical basis for an in-depth understanding of the intrinsic mechanisms underlying the development of L2 writing competence.

The research indicates that L2 writing performance is jointly influenced by multiple individual difference factors, including learners’ language aptitude, working memory, achievement goals, L2 grit, writing self-efficacy, and self-regulated learning strategies. Through structural equation modeling analysis, the paper reveals that these factors do not operate in isolation but form dynamic and complex interactive and mediating pathways. The results show that L2 grit and writing self-efficacy play key mediating roles in the effects of vocabulary learning ability, working memory, and writing achievement goals on writing quality; meanwhile, writing achievement goals, L2 grit, and writing self-efficacy collectively mediate the impact of vocabulary learning ability on writing quality. The study also finds that the interaction patterns of individual difference factors vary across different writing genres (argumentative essays vs. narrative essays), reflecting the moderating effect of writing tasks.

By integrating Hayes’ (2012) Cognitive-Affective Model of Writing and Ellis’ (2004) Interaction Hypothesis of Individual Differences in Second Language Acquisition, this research constructs a comprehensive theoretical framework, deepening the understanding of how cognitive, motivational, and strategic factors synergistically function in the L2 writing process. The findings offer a new perspective for systematically comprehending the complex relationships among L2 learners’ individual differences, and hold significant theoretical and practical implications for promoting personalized writing instruction and designing targeted teaching interventions.

The achievement of this important research fully demonstrates the remarkable effectiveness of SASU’s "Tashi Talent Project" in attracting and cultivating high-level scientific research talents and building innovative teams. It is an inevitable outcome of the university’s sustained efforts to strengthen talent team construction and optimize the academic ecology.

Academic paper link: https://www.sciencedirect.com/science/article/pii/S0959475225001380