ResearchResearch paperEfficiency & Inference · Large Language Models · Interpretability1 source · Oct 19, 2026

SHAM-Bench: A Span-level Hallucination Benchmark Across Multiple Tasks

In this paper, we introduce SHAM-Bench (Span-level Hallucination Benchmark Across Multiple Tasks), a unified benchmark for span-level hallucination detection spanning six NLG tasks, aggregated from existing human-annotated datasets totaling 6,461 examples under a common schema and evaluation protocol.

Key points

  • Span-level hallucination detection pinpoints unsupported content in LLM outputs, enabling actionable feedback and targeted mitigation.
  • Existing evaluations for span-level hallucination detection methods are fragmented across tasks, annotation formats, and metrics, and most span-level datasets cover only a single NLG domain, making it difficult to assess whether a detection method actually generalizes across tasks and domains.
  • Using SHAM-Bench, we evaluate existing hallucination detection methods and find that fine-tuned detectors often perform well in-domain but degrade under distribution shift, whereas prompt-based methods with reasoning are more robust across tasks.
  • We release the dataset, evaluation code, and a public leaderboard to support future research on broadly generalizable hallucination detection.

Sources (1)

  • [1]SHAM-Bench: A Span-level Hallucination Benchmark Across Multiple Tasks
    arXiv (AI, ML, NLP, CV, robotics, multi-agent) · Oct 19, 10:48 PM
    In this paper, we introduce SHAM-Bench (Span-level Hallucination Benchmark Across Multiple Tasks), a unified benchmark for span-level hallucination detection spanning six NLG tasks, aggregated from existing human-annotated datasets totaling 6,461 examples under a common schema and evaluation protocol.
    Span-level hallucination detection pinpoints unsupported content in LLM outputs, enabling actionable feedback and targeted mitigation.

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