Beyond Accuracy: Evaluating Grounded Visual Evidence in Thinking with Images

Xuzhao Li, Xuchen Li, Renjie Pi, Shiyu Hu, Jian Zhao, Jiahui Gao


Abstract
Despite the remarkable progress of Vision-Language Models (VLMs) in adopting "Thinking-with-Images" capabilities, accurately evaluating the authenticity of their reasoning process remains a critical challenge. Existing benchmarks mainly rely on outcome-oriented accuracy, lacking the capability to assess whether models can accurately leverage fine-grained visual cues for multi-step reasoning. To address these limitations, we propose ViEBench, a process-verifiable benchmark designed to evaluate faithful visual reasoning. Comprising 200 multi-scenario high-resolution images with expert-annotated visual evidence, ViEBench uniquely categorizes tasks by difficulty into perception and reasoning dimensions, where reasoning tasks require utilizing localized visual details with prior knowledge. To establish comprehensive evaluation criteria, we introduce a dual-axis matrix that provides fine-grained metrics through four diagnostic quadrants, enabling transparent diagnosis of model behavior across varying task complexities. Our experiments yield several interesting observations: (1) VLMs can sometimes produce correct final answers despite grounding on irrelevant regions, and (2) they may successfully locate the correct evidence but still fail to utilize it to reach accurate conclusions. Our findings demonstrate that ViEBench can serve as a more explainable and practical benchmark for comprehensively evaluating the effectiveness of agentic VLMs.
Anthology ID:
2026.findings-emnlp.596
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
12577–12591
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.596/
DOI:
Bibkey:
Cite (ACL):
Xuzhao Li, Xuchen Li, Renjie Pi, Shiyu Hu, Jian Zhao, and Jiahui Gao. 2026. Beyond Accuracy: Evaluating Grounded Visual Evidence in Thinking with Images. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 12577–12591, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Beyond Accuracy: Evaluating Grounded Visual Evidence in Thinking with Images (Li et al., Findings 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.findings-emnlp.596.pdf