ICA: Information-Aware Credit Assignment for Visually Grounded Long-Horizon Information-Seeking Agents

Cong Pang, Yujie YI, Xuyu Feng, Jiaqi Su, Zixuan Chen, Jiawei Hong, Tiankuo Yao, Nang Yuan, Jiapeng Luo, Lewei Lu, Xin Lou


Abstract
Long-horizon reinforcement learning for information seeking agents remains difficult because terminal rewards reveal whether the final answer is correct, but not which acquired information enabled it. This difficulty is amplified by text-derived webpage observations, where parsing, truncation, and summarization often produce incomplete and unstable content representations across trajectories. We propose an evidence-centric framework for web agent learning that represents information acquired through tools as identifiable units for comparison across trajectories. In particular, fetched webpages are represented as rendered snapshots, preserving layout and multimodal content as stable content-level observations. Building on these units, we introduce Information-Aware Credit Assignment, a post hoc reward propagation method that estimates turn-level utility scores from rollout success rates and assigns dense rewards to intermediate steps that introduced high-utility information. Integrated with GSPO, our method consistently improves performance on BrowseComp, GAIA, Xbench-DS, and Seal-0. Code and datasets will be released at [https://github.com/pc-inno/ICA_MM_deepsearch](https://github.com/pc-inno/ICA_MM_deepsearch).
Anthology ID:
2026.emnlp-main.327
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
7541–7556
Language:
URL:
https://aclanthology.org/2026.emnlp-main.327/
DOI:
Bibkey:
Cite (ACL):
Cong Pang, Yujie YI, Xuyu Feng, Jiaqi Su, Zixuan Chen, Jiawei Hong, Tiankuo Yao, Nang Yuan, Jiapeng Luo, Lewei Lu, and Xin Lou. 2026. ICA: Information-Aware Credit Assignment for Visually Grounded Long-Horizon Information-Seeking Agents. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 7541–7556, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
ICA: Information-Aware Credit Assignment for Visually Grounded Long-Horizon Information-Seeking Agents (Pang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.327.pdf