arXiv AI By Sagnik De, Sreenija Pavuluri

Refusal Is Not Robustness: Auditing Confident Fabrication in Large Language Models on a Provably Uninformative Clinical Pain Speech Transcript

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The study evaluates how large language models handle confident fabrication versus abstention when predicting pain from speech transcripts that contain no lexical pain cues. Using the TAME Pain speech corpus, researchers found that while acoustic features could predict pain, transcript‑only predictions were near chance, indicating unsupported claims. Models prompted cooperatively largely abstained on non‑pain transcripts and accurately extracted pain ratings when present, whereas authority‑framed prompts led to variable abstention and some models (Gemini 2.5 Flash, Llama 3.1 8B) produced confident yet fabricated pain scores.

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