Exploring learner prompting and AI feedback quality in L2 Portuguese writing

Resumen

For L2 Portuguese learners in Macau, artificial intelligence (AI) has become a primary source of immediate writing feedback for Chinese university students. This study investigates authentic learner prompting practices and the accuracy of resulting AI-generated revisions in L2 Portuguese writing. Forty-six second-year Portuguese Studies majors, divided into a control condition and a justification condition that required them to rationalize every modification, revised a first-year learner composition using their preferred AI tools. Results reveal that students predominantly prompted in Chinese, employed highly anthropomorphic and polite language, relied on generic or grammar-focused requests, and frequently exhibited misalignment between intended goals and actual prompts. The requirement to justify revisions increased interaction turns and shifted attention toward smaller textual units and explanation-seeking, though it also produced higher error rates in the resulting revisions. Experiments with researcher-designed prompts demonstrated the potential of simple prompt engineering strategies, with the Rephrase-and-Respond technique eliciting the most accurate revisions. The findings underscore the immaturity of untrained prompting, the context-sensitive nature of prompt engineering, and the practical pedagogical value of current LLMs even under naïve use. To foster critical and reflective human–AI collaboration in L2 writing, pedagogical interventions such as explicit instruction in prompting strategies and the use of tasks that require justification or explanation-seeking are recommended.