arXiv AI
Sep 15

How Semantically Stable Are LLM Refusals? Measuring Confusion in Local Safety Boundaries

The paper introduces Semantic Confusion to assess how consistently large language models refuse similar prompts. It presents ParaGuard, a 10k‑prompt corpus of controlled paraphrase clusters, and proposes three token‑level metrics—Confusion Index, Confusion Rate, and Confusion Depth—to measure contradictory refusal decisions across meaning‑preserving paraphrases. Experiments show that global false rejection rates can mask local inconsistencies, revealing that refusal evaluation must consider both frequency and consistency across nearby paraphrases.

By Riad Ahmed Anonto, Md Labid Al Nahiyan, Md Tanvir Hassan