Mitigating Hallucination in Vision-Language Models through Barrier-Regulated Adaptive Closed-form Steering

Soumyadeep Jana, Pulkit Mittal, Ranbir Singh Sanasam


Abstract
Large vision-language models (LVLMs) often hallucinate objects that are not present in the input image, largely because visual grounding weakens as decoding progresses. Existing inference-time mitigation methods modify logits or hidden states throughout generation, but they suffer from three key limitations: they lack an explicit grounding objective, intervene even when the model is already well-grounded, and use fixed correction strengths that do not adapt to the severity of grounding failure. We propose BRACS (Barrier-Regulated Adaptive Closed-form Steering), a training-free steering framework that addresses these issues through barrier-regulated adaptive closed-form steering. BRACS monitors the model’s own attention to measure visual grounding and applies corrections to the hidden states only when grounding deteriorates. The corrective update is computed analytically in closed form, requiring no training of auxiliary networks or model retraining. Experiments on LLaVA-1.5-7B and Qwen-VL-Chat show that BRACS consistently outperforms prior methods on hallucination benchmarks, reducing CHAIRs by 9.4 points and improving POPE F1 by 2.7 points, while matching or improving performance on four general multimodal benchmarks. BRACS also remains efficient, operating at 80% of greedy decoding throughput and achieving 1.3× higher speed on average than the baselines.
Anthology ID:
2026.emnlp-main.1662
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:
37790–37801
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1662/
DOI:
Bibkey:
Cite (ACL):
Soumyadeep Jana, Pulkit Mittal, and Ranbir Singh Sanasam. 2026. Mitigating Hallucination in Vision-Language Models through Barrier-Regulated Adaptive Closed-form Steering. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 37790–37801, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Mitigating Hallucination in Vision-Language Models through Barrier-Regulated Adaptive Closed-form Steering (Jana et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1662.pdf