When Do LLMs Need Retrieval Augmentation? Mitigating LLMs’ Overconfidence Helps Retrieval Augmentation

Shiyu Ni, Keping Bi, Jiafeng Guo, Xueqi Cheng


Abstract
Large Language Models (LLMs) have been found to have difficulty knowing they do not possess certain knowledge and tend to provide specious answers in such cases. Retrieval Augmentation (RA) has been extensively studied to mitigate LLMs’ hallucinations. However, due to the extra overhead and unassured quality of retrieval, it may not be optimal to conduct RA all the time. A straightforward idea is to only conduct retrieval when LLMs are uncertain about a question. This motivates us to enhance the LLMs’ ability to perceive their knowledge boundaries to help RA. In this paper, we first quantitatively measure LLMs’ such ability and confirm their overconfidence. Then, we study how LLMs’ certainty about a question correlates with their dependence on external retrieved information. We propose several methods to enhance LLMs’ perception of knowledge boundaries and show that they are effective in reducing overconfidence. Additionally, equipped with these methods, LLMs can achieve comparable or even better performance of RA with much fewer retrieval calls.
Anthology ID:
2024.findings-acl.675
Volume:
Findings of the Association for Computational Linguistics ACL 2024
Month:
August
Year:
2024
Address:
Bangkok, Thailand and virtual meeting
Editors:
Lun-Wei Ku, Andre Martins, Vivek Srikumar
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
11375–11388
Language:
URL:
https://aclanthology.org/2024.findings-acl.675
DOI:
Bibkey:
Cite (ACL):
Shiyu Ni, Keping Bi, Jiafeng Guo, and Xueqi Cheng. 2024. When Do LLMs Need Retrieval Augmentation? Mitigating LLMs’ Overconfidence Helps Retrieval Augmentation. In Findings of the Association for Computational Linguistics ACL 2024, pages 11375–11388, Bangkok, Thailand and virtual meeting. Association for Computational Linguistics.
Cite (Informal):
When Do LLMs Need Retrieval Augmentation? Mitigating LLMs’ Overconfidence Helps Retrieval Augmentation (Ni et al., Findings 2024)
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PDF:
https://aclanthology.org/2024.findings-acl.675.pdf