Probing-RAG: Self-Probing to Guide Language Models in Selective Document Retrieval

Ingeol Baek, Hwan Chang, ByeongJeong Kim, Jimin Lee, Hwanhee Lee


Abstract
Retrieval-Augmented Generation (RAG) enhances language models by retrieving and incorporating relevant external knowledge. However, traditional retrieve-and-generate processes may not be optimized for real-world scenarios, where queries might require multiple retrieval steps or none at all. In this paper, we propose a Probing-RAG, which utilizes the hidden state representations from the intermediate layers of language models to adaptively determine the necessity of additional retrievals for a given query. By employing a pre-trained prober, Probing-RAG effectively captures the model’s internal cognition, enabling reliable decision-making about retrieving external documents. Experimental results across five open-domain QA datasets demonstrate that Probing-RAG outperforms previous methods while reducing the number of redundant retrieval steps.
Anthology ID:
2025.findings-naacl.181
Volume:
Findings of the Association for Computational Linguistics: NAACL 2025
Month:
April
Year:
2025
Address:
Albuquerque, New Mexico
Editors:
Luis Chiruzzo, Alan Ritter, Lu Wang
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
3287–3304
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URL:
https://preview.aclanthology.org/Ingest-2025-COMPUTEL/2025.findings-naacl.181/
DOI:
Bibkey:
Cite (ACL):
Ingeol Baek, Hwan Chang, ByeongJeong Kim, Jimin Lee, and Hwanhee Lee. 2025. Probing-RAG: Self-Probing to Guide Language Models in Selective Document Retrieval. In Findings of the Association for Computational Linguistics: NAACL 2025, pages 3287–3304, Albuquerque, New Mexico. Association for Computational Linguistics.
Cite (Informal):
Probing-RAG: Self-Probing to Guide Language Models in Selective Document Retrieval (Baek et al., Findings 2025)
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https://preview.aclanthology.org/Ingest-2025-COMPUTEL/2025.findings-naacl.181.pdf