Bridging Domains in Mental Stress Assessment via Retrieval-Augmented Reasoning

Mental stress assessment is crucial for mental and physical well-being. However, it faces limitations due to domain fragmentation, in which contextual variations in stress triggers and demographics hinder the generalization of assessment models across real-world scenarios. Additionally, mental stress assessment is sensitive and human-centric due to its implications for mental health interventions, emphasizing the need for model transparency and trustworthiness. To address this gap, we propose Retrieval-Augmented Reasoning, a novel framework that bridges domain gaps in mental stress assessment through transparent step-by-step reasoning and dynamic in-context example retrieval. Our framework introduces two key components: (1) a ''detect-then-assess'' reasoning chain decouples stress-relevant facial action units (AUs) from domain-specific noise by first generating textual descriptions as intermediate reasoning step (e.g., ''eyebrow: inner portions raised''). The model then reflects on and learns to refine these descriptions via Direct Preference Optimization (DPO), ensuring faithfulness and helpfulness; (2) a dual-encoder multimodal retriever dynamically selects proper in-context examples from source domain to enhance target-domain assessments, leveraging feedback from the assessment model to optimize retrieval. Experimental results demonstrate that our framework consistently outperforms large multimodal foundation models, stress assessment baselines, and domain generalization methods.