Towards Mitigating LLM Hallucination via Self Reflection
Summary
Large language models used for medical question answering often produce fluent but unsupported or incorrect statements, known as hallucinations. This is especially dangerous in healthcare, where terminology is specialized and errors can affect patient care. The authors first measure the problem. They prompt five LLMs zero-shot on five medical generative QA datasets. Three are general models (Vicuna, Alpaca-LoRA, ChatGPT) and two are medical models (MedAlpaca, Robin-medical). They sort flawed outputs into fact inconsistency, query inconsistency and tangentiality.
They then propose an iterative self-reflection loop that needs no extra training. The model writes background knowledge for the question, rates its factuality and revises it until it is good enough. It then answers using that knowledge and checks two things: whether the answer agrees with the knowledge, and whether it addresses the question. If the answer fails, the model revises it or restarts the cycle.
Automatic and human evaluations show fewer hallucinations than direct answering, for models from 7B to 175B parameters and on all five datasets. The approach draws more reliable output from a model's own parametric knowledge and could be combined with retrieval.
Key points
- Datasets: PubMedQA (1k expert-labeled instances with questions built from article titles), MedQuAD, MEDIQA2019, LiveMedQA2017 and MASH-QA.
- Evaluation combines unigram F1 and ROUGE-L with hallucination-oriented metrics (MedNLI, CtrlEval) and human judgment. The authors note that n-gram overlap scores poorly detect hallucinated answers.
- Ablations show the value of three design choices. Removing the refinement stage, the explicit aspect descriptions, or the numeric scores in the feedback each lowers MedNLI and CtrlEval.
- Stated limitations: the method reduces but does not eliminate hallucination, covers only English medical queries, and is not yet ready for real-world deployment.
- Code is released at github.com/ziweiji/Self_Reflection_Medical.
Cited by
- Towards Reasoning Era: A Survey of Long Chain-of-Thought for Reasoning Large Language Models
- Large Legal Fictions: Profiling Legal Hallucinations in Large Language Models
Cite
@inproceedings{ji2023mitigating,
title = {{Towards Mitigating LLM Hallucination via Self Reflection}},
author = {Ji, Ziwei and Yu, Tiezheng and Xu, Yan and Lee, Nayeon and Ishii, Etsuko and Fung, Pascale},
booktitle = {Findings of the Association for Computational Linguistics: EMNLP 2023},
year = {2023},
doi = {10.18653/v1/2023.findings-emnlp.123},
url = {https://doi.org/10.18653/v1/2023.findings-emnlp.123}
}References
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