The growing demand for accessible mental health support requires training more counselors, yet existing approaches remain resource-intensive and difficult to scale. LLMs can realistically simulate patients and generate actionable feedback for training, but their actual impact on novice counselor skill development remains unknown. We developed an LLM-simulated practice and feedback system and conducted a randomized study with 94 novice counselors, comparing practice alone versus practice with feedback. We evaluated behavioral performance, self-efficacy, and qualitative reflections. Results showed the practice-and-feedback group improved in client-centered microskills (reflections, questions), while the practice-alone group showed no improvements. For empathy, the practice-alone group declined over time and performed significantly worse than the feedback group. Qualitative interviews reinforced these findings: feedback helped participants adopt a client-centered listening approach, while practice-alone participants remained solution-oriented. These results suggest LLM-based training systems can promote effective skill development, and combining simulated practice with structured feedback is critical for meaningful improvement.

翻译：日益增长的心理健康支持需求要求培训更多咨询师，但现有方法仍资源密集且难以规模化。大型语言模型（LLM）能够逼真地模拟患者并为培训提供可操作的反馈，但其对新手咨询师技能发展的实际影响尚不明确。我们开发了一套LLM模拟实践与反馈系统，并对94名新手咨询师开展了一项随机研究，比较了单纯实践与结合反馈的实践效果。我们评估了行为表现、自我效能感及质性反思。结果显示，实践加反馈组在以来访者为中心的微技能（如反映、提问）方面有所提升，而单纯实践组未显示进步。在共情方面，单纯实践组随时间推移出现下降，且表现显著差于反馈组。质性访谈进一步印证了这些发现：反馈帮助参与者采用以来访者为中心的倾听方式，而单纯实践者仍保持问题解决导向。这些结果表明，基于LLM的培训系统能够促进有效的技能发展，且将模拟实践与结构化反馈相结合对于实现实质性提升至关重要。