Fooling the LVLM Judges: Visual Biases in LVLM-Based Evaluation

Yerin Hwang, Dongryeol Lee, Kyungmin Min, Taegwan Kang, Yongil Kim, Kyomin Jung


Abstract
Recently, large vision–language models (LVLMs) have emerged as the preferred tools for judging text–image alignment, yet their robustness along the visual modality remains underexplored. This work is the first study to address a key research question: Can adversarial visual manipulations systematically fool LVLM judges into assigning unfairly inflated scores? We define potential image-induced biases within the context of T2I evaluation and examine how these biases affect the evaluations of LVLM judges. Moreover, we introduce a novel, fine-grained, multi-domain meta-evaluation benchmark named FRAME, which is deliberately constructed to exhibit diverse score distributions. By introducing the defined biases into the benchmark, we reveal that all tested LVLM judges exhibit vulnerability across all domains, consistently inflating scores for manipulated images. Further analysis reveals that combining multiple biases amplifies their effects, and pairwise evaluations are similarly susceptible. Moreover, we observe that visual biases persist despite prompt-based mitigation strategies, highlighting the vulnerability of current LVLM evaluation systems and underscoring the urgent need for more robust LVLM judges.
Anthology ID:
2025.emnlp-main.1182
Volume:
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
Month:
November
Year:
2025
Address:
Suzhou, China
Editors:
Christos Christodoulopoulos, Tanmoy Chakraborty, Carolyn Rose, Violet Peng
Venue:
EMNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
23197–23216
Language:
URL:
https://preview.aclanthology.org/ingest-emnlp/2025.emnlp-main.1182/
DOI:
Bibkey:
Cite (ACL):
Yerin Hwang, Dongryeol Lee, Kyungmin Min, Taegwan Kang, Yongil Kim, and Kyomin Jung. 2025. Fooling the LVLM Judges: Visual Biases in LVLM-Based Evaluation. In Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing, pages 23197–23216, Suzhou, China. Association for Computational Linguistics.
Cite (Informal):
Fooling the LVLM Judges: Visual Biases in LVLM-Based Evaluation (Hwang et al., EMNLP 2025)
Copy Citation:
PDF:
https://preview.aclanthology.org/ingest-emnlp/2025.emnlp-main.1182.pdf
Checklist:
 2025.emnlp-main.1182.checklist.pdf