Towards Grounded Hallucination Definitions for Biomedical Question Answering with Reproducible Examples from ClinIQLink
Brandon Colelough, Davis Bartels, Madeline Bittner, Dina Demner-Fushman
Abstract
Hallucinations in biomedical question answering are hard to define and compare because the literature uses overlapping and inconsistent terms. There is currently no grounded definition set that works for biomedical QA, with real examples from open-source LLMs. We introduce a layered definition of hallucinations for biomedical QA, hierarchically structured from the overarching idea of Hallucination in relation to generated model content, to source and consistency orientations, and finally to subtypes. We ground our definition taxonomy in source-attributed literature definitions and reproducible examples from REMOVED FOR REVIEW, where cases can be traced to the question, source passage, generated answer, and annotation record. We provide a framework with annotation, comparison, and error analysis to provide a clearer reference for evidence-grounded biomedical QA. We aim for this example-grounded taxonomy to support automated detection of hallucinations and their potential harmfulness.- Anthology ID:
- 2026.bionlp-1.67
- Volume:
- BioNLP 2026
- Month:
- July
- Year:
- 2026
- Address:
- San Diego, California
- Editors:
- Dina Demner-Fushman, Sophia Ananiadou, Kirk Roberts, Junichi Tsujii
- Venues:
- BioNLP | WS
- SIG:
- Publisher:
- Association for Computational Linguistics
- Note:
- Pages:
- 812–842
- Language:
- URL:
- https://preview.aclanthology.org/ingest-acl-workshops/2026.bionlp-1.67/
- DOI:
- Cite (ACL):
- Brandon Colelough, Davis Bartels, Madeline Bittner, and Dina Demner-Fushman. 2026. Towards Grounded Hallucination Definitions for Biomedical Question Answering with Reproducible Examples from ClinIQLink. In BioNLP 2026, pages 812–842, San Diego, California. Association for Computational Linguistics.
- Cite (Informal):
- Towards Grounded Hallucination Definitions for Biomedical Question Answering with Reproducible Examples from ClinIQLink (Colelough et al., BioNLP 2026)
- PDF:
- https://preview.aclanthology.org/ingest-acl-workshops/2026.bionlp-1.67.pdf