The Hidden Life of Tokens: Reducing Hallucination of Large
  Vision-Language Models via Visual Information Steering
Authors: name: Zhuowei Li, name: Haizhou Shi, name: Yunhe Gao, name: Di Liu, name: Zhenting Wang, name: Yuxiao Chen, name: Ting Liu, name: Long Zhao, name: Hao Wang, name: Dimitris N. Metaxas

Large Vision-Language Models (LVLMs) can reason effectively over both textual
and visual inputs, but they tend to hallucinate syntactically coherent yet
visually ungrounded contents. In this paper, we investigate the internal
dynamics of hallucination by examining the tokens logits rankings throughout
the generation process, revealing three key patterns in how LVLMs process
information: (1) gradual visual information loss -- visually grounded tokens
gradually become less favored throughout generation, and (2) early excitation
-- semantically meaningful tokens achieve peak activation in the layers earlier
than the final layer. (3) hidden genuine information -- visually grounded
tokens though not being eventually decided still retain relatively high
rankings at inference. Based on these insights, we propose VISTA (Visual
Information Steering with Token-logit Augmentation), a training-free
inference-time intervention framework that reduces hallucination while
promoting genuine information. VISTA works by combining two complementary
approaches: reinforcing visual information in activation space and leveraging
early layer activations to promote semantically meaningful decoding. Compared
to existing methods, VISTA requires no external supervision and is applicable
to various decoding strategies. Extensive experiments show that VISTA on
average reduces hallucination by abount 40% on evaluated open-ended generation
task, and it consistently outperforms existing methods on four benchmarks
across four architectures under three decoding strategies.