Taming Object Hallucinations with Verified Atomic Confidence Estimation

Jiarui Liu, Weihao Xuan, Zhijing Jin, Mona T. Diab


Abstract
Multimodal Large Language Models (MLLMs) often suffer from hallucinations, particularly errors in object existence, attributes, or relations, which undermine their reliability. We introduce TACO (Verified Atomic Confidence Estimation), a simple framework that mitigates hallucinations through self-verification and confidence calibration without relying on external vision experts. TACO decomposes responses into atomic queries, paraphrases them to reduce sensitivity to wording, and estimates confidence using self-consistency (black-box) or self-confidence (gray-box) aggregation, before refining answers with a language model. Experiments on five benchmarks (POPE, MME, HallusionBench, AMBER, and MM-Hal Bench) with two MLLMs (LLaVA-1.5-7B and CogVLM2) show that TACO consistently outperforms direct prompting and Visual Contrastive Decoding, reduces systematic biases, and improves confidence calibration, demonstrating its effectiveness in enhancing the faithfulness of MLLMs.
Anthology ID:
2026.eacl-long.252
Volume:
Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
March
Year:
2026
Address:
Rabat, Morocco
Editors:
Vera Demberg, Kentaro Inui, Lluís Marquez
Venue:
EACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
5430–5444
Language:
URL:
https://preview.aclanthology.org/ingest-eacl/2026.eacl-long.252/
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Bibkey:
Cite (ACL):
Jiarui Liu, Weihao Xuan, Zhijing Jin, and Mona T. Diab. 2026. Taming Object Hallucinations with Verified Atomic Confidence Estimation. In Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 1: Long Papers), pages 5430–5444, Rabat, Morocco. Association for Computational Linguistics.
Cite (Informal):
Taming Object Hallucinations with Verified Atomic Confidence Estimation (Liu et al., EACL 2026)
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PDF:
https://preview.aclanthology.org/ingest-eacl/2026.eacl-long.252.pdf