Jiexi Xu
2026
Fixing Semantic Blind Spots in Anchor Tokens of dMLLMs
Ruixuan Xu | Jiexi Xu | Qiyan Zhao | Xiaofeng Zhang
Findings of the Association for Computational Linguistics: ACL 2026
Ruixuan Xu | Jiexi Xu | Qiyan Zhao | Xiaofeng Zhang
Findings of the Association for Computational Linguistics: ACL 2026
Recent advances in diffusion-based Multimodal Large Language Models (dMLLMs) offer a compelling alternative to autoregressive counterparts; however, they remain prone to hallucinations. Through information flow analysis on LLaDA-V, we identify two intertwined factors contributing to this issue. First, although the special tokens serve as semantic anchors for aggregating visual information, they simultaneously induce severe attention sinks, excessively consuming the model’s attention budget. Second, the long-range decay inherent in Rotary Position Embedding (RoPE) leads to semantic blind spots, preventing these anchors from uniformly perceiving the entire visual input. Accordingly, our objective is to moderately alleviate the attention sink effect on semantic anchors while enhancing their ability to aggregate global visual information, thereby eliminating semantic blind spots. To this end, we propose Extrinsic Distance-Aware Regularization (EDAR), a training-free decoding strategy that augments the attention key space with a static, distance-aware matrix. This matrix jointly redistributes excessive attention away from anchors and injects absolute positional bias to ensure uniform visual coverage. Experiments on LLaDA-V demonstrate that EDAR effectively eliminates semantic blind spots and achieves state-of-the-art performance on both hallucination-specific and general multimodal benchmarks.
2025
Can LLMs Recognize Their Own Analogical Hallucinations? Evaluating Uncertainty Estimation for Analogical Reasoning
Zheng Chen | Zhaoxin Feng | Jianfei Ma | Jiexi Xu | Bo Li
Proceedings of the 3rd Workshop on Towards Knowledgeable Foundation Models (KnowFM)
Zheng Chen | Zhaoxin Feng | Jianfei Ma | Jiexi Xu | Bo Li
Proceedings of the 3rd Workshop on Towards Knowledgeable Foundation Models (KnowFM)
Large language models (LLMs) often demonstrate strong performance by leveraging implicit knowledge acquired during pretraining. Analogical reasoning, which solves new problems by referencing similar known examples, offers a structured way to utilize this knowledge, but can also lead to subtle factual errors and hallucinations. In this work, we investigate whether LLMs can recognize the reliability of their own analogical outputs using black-box uncertainty estimation (UE). We evaluate six UE metrics across two reasoning-intensive tasks: mathematical problem solving (GSM8K) and code generation (Codeforces). Our results show that Kernel Language Entropy (KLE) and Lexical Similarity (LexSim) are the most robust indicators of correctness. Moreover, while analogical prompting increases model confidence over direct prompting, most uncertainty arises during the analogy transfer step. These findings highlight the limitations of analogical knowledge transfer in LLMs and demonstrate the potential of UE methods for detecting hallucinated reasoning in black-box settings.