@inproceedings{li-etal-2026-bridgegap,
title = "{B}ridge{G}ap: Belief-Grounded Training for Medical Dialogue Agents",
author = "Li, Weijun and
Yang, Tao and
Yang, Jiayu and
Chao, Fei",
editor = "Lee, Hung-Yi and
Dev, Sunipa and
Li, Jessy and
Elliott, Desmond",
booktitle = "Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing",
month = oct,
year = "2026",
address = "Budapest, Hungary",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.emnlp-main.1974/",
pages = "44932--44947",
ISBN = "979-8-89176-459-0",
abstract = "Although LLMs perform well on static medical QA, adapting them to multi-turn diagnostic dialogue remains challenging: agents forget confirmed symptoms, ask redundant questions, and fail to narrow differentials, largely because they lack an explicit representation of their evolving clinical understanding. Our key insight is that a structured belief state{---}encoding accumulated evidence, ranked differential diagnoses with confidence, and prioritized next questions{---}can simultaneously serve as a supervision target, a basis for rule-based reward computation, and a grounding context for deciding what to ask next. We propose BridgeGap, a two-stage framework in which supervised fine-tuning on silver-annotated belief states teaches the agent to maintain structured clinical reasoning, while reinforcement learning with a belief-progress reward refines questioning strategy through dense, environment-verified per-turn feedback without LLM judges or learned reward models. On HealthBench, BridgeGap (8B) surpasses Doctor-R1 (8B) by 2.84 points and the 4{\texttimes} larger Baichuan-M2-32B by 5.85 points; on AgentClinic, it achieves 44.6{\%} diagnostic accuracy in 10.5 average turns, compared to 37.6{\%} in 15.5 turns for Doctor-R1. Across evaluations, BridgeGap advances interactive diagnosis while preserving factual knowledge on static medical benchmarks."
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<abstract>Although LLMs perform well on static medical QA, adapting them to multi-turn diagnostic dialogue remains challenging: agents forget confirmed symptoms, ask redundant questions, and fail to narrow differentials, largely because they lack an explicit representation of their evolving clinical understanding. Our key insight is that a structured belief state—encoding accumulated evidence, ranked differential diagnoses with confidence, and prioritized next questions—can simultaneously serve as a supervision target, a basis for rule-based reward computation, and a grounding context for deciding what to ask next. We propose BridgeGap, a two-stage framework in which supervised fine-tuning on silver-annotated belief states teaches the agent to maintain structured clinical reasoning, while reinforcement learning with a belief-progress reward refines questioning strategy through dense, environment-verified per-turn feedback without LLM judges or learned reward models. On HealthBench, BridgeGap (8B) surpasses Doctor-R1 (8B) by 2.84 points and the 4× larger Baichuan-M2-32B by 5.85 points; on AgentClinic, it achieves 44.6% diagnostic accuracy in 10.5 average turns, compared to 37.6% in 15.5 turns for Doctor-R1. Across evaluations, BridgeGap advances interactive diagnosis while preserving factual knowledge on static medical benchmarks.</abstract>
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%0 Conference Proceedings
%T BridgeGap: Belief-Grounded Training for Medical Dialogue Agents
%A Li, Weijun
%A Yang, Tao
%A Yang, Jiayu
%A Chao, Fei
%Y Lee, Hung-Yi
%Y Dev, Sunipa
%Y Li, Jessy
%Y Elliott, Desmond
%S Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
%D 2026
%8 October
%I Association for Computational Linguistics
%C Budapest, Hungary
%@ 979-8-89176-459-0
%F li-etal-2026-bridgegap
%X Although LLMs perform well on static medical QA, adapting them to multi-turn diagnostic dialogue remains challenging: agents forget confirmed symptoms, ask redundant questions, and fail to narrow differentials, largely because they lack an explicit representation of their evolving clinical understanding. Our key insight is that a structured belief state—encoding accumulated evidence, ranked differential diagnoses with confidence, and prioritized next questions—can simultaneously serve as a supervision target, a basis for rule-based reward computation, and a grounding context for deciding what to ask next. We propose BridgeGap, a two-stage framework in which supervised fine-tuning on silver-annotated belief states teaches the agent to maintain structured clinical reasoning, while reinforcement learning with a belief-progress reward refines questioning strategy through dense, environment-verified per-turn feedback without LLM judges or learned reward models. On HealthBench, BridgeGap (8B) surpasses Doctor-R1 (8B) by 2.84 points and the 4× larger Baichuan-M2-32B by 5.85 points; on AgentClinic, it achieves 44.6% diagnostic accuracy in 10.5 average turns, compared to 37.6% in 15.5 turns for Doctor-R1. Across evaluations, BridgeGap advances interactive diagnosis while preserving factual knowledge on static medical benchmarks.
%U https://aclanthology.org/2026.emnlp-main.1974/
%P 44932-44947
Markdown (Informal)
[BridgeGap: Belief-Grounded Training for Medical Dialogue Agents](https://aclanthology.org/2026.emnlp-main.1974/) (Li et al., EMNLP 2026)
ACL