Development of syntactic complexity in Chinese EFL learners across two proficiency levels and two written genres

This study examined the effects of time, genre, and their interaction on large- and fine-grained syntactic complexity (SC) measures in a set of argumentative and narrative essays produced by Chinese English-as-a-foreign-language (EFL) learners at two different proficiency levels over the course of one semester. The goal of the study was to partially replicate and extend Yoon and Polio's (2017) and Lei et al.’s (2023) studies on these effects, both of which focused on a single group of adult or college-level second language (L2) English learners and employed a set of large-grained indices to gauge SC. This was done to test the generalizability of their findings regarding the effects of time, genre, and their interaction on L2 writing SC to diverse learner groups and obtain a more comprehensive understanding of such effects. Our results revealed significant, differential effects of time, genre, and their interaction on large- and fine-grained SC indices in the two learner groups. These findings contribute to a more nuanced understanding of L2 writing SC development and the effect of genre on this development.