The impact of GenAI chatbots on communicative competence in EFL writing in Chinese upper secondary school

In English language learning, generative artificial intelligence (GenAI) chatbots can support students’ writing by providing context-based examples and guiding idea organization. Yet, improving discourse-level writing remains challenging, as feedback often targets accuracy rather than meaning. This study investigates the impact of GenAI chatbots in writing instruction compared with the traditional method on the communicative competence (CC) of Chinese upper secondary English as a Foreign Language (EFL) students. A quasi-experimental study was conducted over a semester with 154 Grade 11 students. The experimental group (n = 76) worked with DeepSeek, while the control group (n = 78) received traditional teacher instruction. Writing was assessed three times using a four-dimensional analytic rubric with 20 items covering grammatical, sociolinguistic, discourse, and strategic competences. Repeated-measures ANOVA revealed greater improvements in the DeepSeek group across all four competence dimensions, with the most notable gains in grammatical and sociolinguistic competence. Item-level analysis showed the largest increases in sentence structure, character voice, and social awareness. In contrast, idea order improved less in the DeepSeek group than in the control group, suggesting that higher-level organization still requires human mediation for effective development. The findings point to the value of incorporating GenAI chatbots into EFL writing instruction to support CC development. When used collaboratively with teacher guidance, GenAI chatbots can better support discourse and pragmatic skills that require sustained attention.