U-Lens: Supporting User Uncertainty Management in Long-Form LLM Responses
Uncertainty can appear throughout LLM-generated text (e.g., questionable claims, ambiguous terms). Prior work largely focuses on making such uncertainty visible through cues such as confidence scores, but seeing uncertainty is not the same as managing it. Through a formative study, we examine uncertainty management across interpretation, evaluation, and decision. From these insights, we derive design guidelines for uncertainty target representation, evaluative explanation, response guidance, and interactive presentation. We instantiate them in U-Lens, an uncertainty-management system that organizes uncertain information into contextual inspection targets, prioritizes them, and links each to evaluative context and response options. In an 18-participant within-subjects study comparing U-Lens with a confidence-cue baseline, U-Lens improved verification efficiency and effort allocation, reduced perceived workload, and strengthened support across all three stages. This work reframes uncertainty support for generative AI from text-centered cues to a user-centered process of interpreting, evaluating, and acting on uncertainty.