Xiaojun Chang
Author directory2026
HEAL: Latent Head Alignment for Post-Training Quantization of Large Language Models
Mingzhe Yang | Sihao Lin | Ruibo Zhang | Xinyuan Zhu | Lei Chen | Weidong Chen | Xiaojun Chang
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Mingzhe Yang | Sihao Lin | Ruibo Zhang | Xinyuan Zhu | Lei Chen | Weidong Chen | Xiaojun Chang
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Post-training quantization (PTQ) has become a key approach for large language model (LLM) compression. Existing methods commonly adopt block-level reconstruction as a surrogate to calibrate each quantized Transformer block. However, our analysis shows that this loose objective can admit cancellation patterns, where the aggregated block-level reconstruction error is small even though the per-head errors remain large. We therefore revisit the PTQ formulation from a variational perspective. By treating per-head representations as latent variables and the block output as the observed variable, we find that conventional block-level reconstruction corresponds to optimizing only the observation-level term, while omitting a latent alignment term that captures head-level quantization error. Motivated by this finding, we propose HEAL, a Latent HEad ALignment framework that turns block-level reconstruction calibration into joint observation-latent calibration with stop-gradient head alignment. Experiments on LLaMA-2/3 and Qwen2.5 families under low-bit weight-activation quantization show that HEAL generally improves perplexity and zero-shot accuracy over block-level reconstruction baselines.
Beyond Survival: Evaluating LLMs in Social Deduction Games with Human-Aligned Strategies
Zirui Song | Yuan Huang | Junchang Liu | Haozhe Luo | Chenxi Wang | Lang Gao | Zixiang Xu | Bairui Zhang | Mingfei Han | Xiaojun Chang | Xiuying Chen
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Zirui Song | Yuan Huang | Junchang Liu | Haozhe Luo | Chenxi Wang | Lang Gao | Zixiang Xu | Bairui Zhang | Mingfei Han | Xiaojun Chang | Xiuying Chen
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Social deduction games like Werewolf combine language, reasoning, and strategy, providing a testbed for studying language and social intelligence. However, most studies reduce the game to LLM-based self-play, yielding templated utterances and anecdotal cases that overlook the richness of social gameplay. Evaluation further relies on coarse metrics such as survival time or subjective scoring due to the lack of quality reference data. To address these gaps, we curate a high-quality, human-verified, multilingual, and multimodal Werewolf dataset containing over 100 hours of video, 32.4M utterance tokens, and 15 rule variants. Based on this dataset, we propose a novel strategy-alignment evaluation that leverages the winning faction’s strategies as ground truth in two stages: 1) Speech evaluation, formulated as multiple-choice-style tasks that assess whether the model can adopt appropriate stances across five dimensions of social ability. 2) Decision evaluation, which assesses the model’s voting choices and opponent-role inferences. This framework enables a fine-grained evaluation of models’ linguistic and reasoning capabilities, while capturing their ability to generate strategically coherent gameplay. Our experiments show that state-of-the-art LLMs and VLMs exhibit diverse performance, with roughly half of the models in both modalities remaining below 0.50 accuracy, revealing clear gaps in deception and counterfactual reasoning.
Measuring Social Bias in Vision-Language Models with Face-Only Counterfactuals from Real Photos
Haodong Chen | Qiang Huang | Jiaqi Zhao | Qiuping Jiang | Xiaojun Chang | Jun Yu
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Haodong Chen | Qiang Huang | Jiaqi Zhao | Qiuping Jiang | Xiaojun Chang | Jun Yu
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Vision-Language Models (VLMs) are increasingly deployed in socially consequential settings, raising concerns about social bias driven by demographic cues. A central challenge in measuring such social bias is attribution under visual confounding: real-world images entangle race and gender with correlated factors such as background and clothing, obscuring attribution. We propose a face-only counterfactual evaluation paradigm that isolates demographic effects while preserving real-image realism. Starting from real photographs, we generate counterfactual variants by editing only facial attributes related to race and gender, keeping all other visual factors fixed. Based on this paradigm, we construct FOCUS, a dataset of 480 scene-matched counterfactual images across six occupations and ten demographic groups, and propose REFLECT, a benchmark comprising three decision-oriented tasks: two-alternative forced choice, multiple-choice socioeconomic inference, and numeric salary recommendation. Experiments on five state-of-the-art VLMs reveal that demographic disparities persist under strict visual control and vary substantially across task formulations. These findings underscore the necessity of controlled, counterfactual audits and highlight task design as a critical factor in evaluating social bias in multimodal models.
2023
ViLPAct: A Benchmark for Compositional Generalization on Multimodal Human Activities
Terry Yue Zhuo | Yaqing Liao | Yuecheng Lei | Lizhen Qu | Gerard de Melo | Xiaojun Chang | Yazhou Ren | Zenglin Xu
Findings of the Association for Computational Linguistics: EACL 2023
Terry Yue Zhuo | Yaqing Liao | Yuecheng Lei | Lizhen Qu | Gerard de Melo | Xiaojun Chang | Yazhou Ren | Zenglin Xu
Findings of the Association for Computational Linguistics: EACL 2023
We introduce ViLPAct, a novel vision-language benchmark for human activity planning. It is designed for a task where embodied AI agents can reason and forecast future actions of humans based on video clips about their initial activities and intents in text. The dataset consists of 2.9k videos from Charades extended with intents via crowdsourcing, a multi-choice question test set, and four strong baselines. One of the baselines implements a neurosymbolic approach based on a multi-modal knowledge base (MKB), while the other ones are deep generative models adapted from recent state-of-the-art (SOTA) methods. According to our extensive experiments, the key challenges are compositional generalization and effective use of information from both modalities.
2022
PAR: Political Actor Representation Learning with Social Context and Expert Knowledge
Shangbin Feng | Zhaoxuan Tan | Zilong Chen | Ningnan Wang | Peisheng Yu | Qinghua Zheng | Xiaojun Chang | Minnan Luo
Proceedings of the 2022 Conference on Empirical Methods in Natural Language Processing
Shangbin Feng | Zhaoxuan Tan | Zilong Chen | Ningnan Wang | Peisheng Yu | Qinghua Zheng | Xiaojun Chang | Minnan Luo
Proceedings of the 2022 Conference on Empirical Methods in Natural Language Processing
Modeling the ideological perspectives of political actors is an essential task in computational political science with applications in many downstream tasks. Existing approaches are generally limited to textual data and voting records, while they neglect the rich social context and valuable expert knowledge for holistic ideological analysis. In this paper, we propose PAR, a Political Actor Representation learning framework that jointly leverages social context and expert knowledge. Specifically, we retrieve and extract factual statements about legislators to leverage social context information. We then construct a heterogeneous information network to incorporate social context and use relational graph neural networks to learn legislator representations. Finally, we train PAR with three objectives to align representation learning with expert knowledge, model ideological stance consistency, and simulate the echo chamber phenomenon. Extensive experiments demonstrate that PAR is better at augmenting political text understanding and successfully advances the state-of-the-art in political perspective detection and roll call vote prediction. Further analysis proves that PAR learns representations that reflect the political reality and provide new insights into political behavior.
2020
Unsupervised Multimodal Neural Machine Translation with Pseudo Visual Pivoting
Po-Yao Huang | Junjie Hu | Xiaojun Chang | Alexander Hauptmann
Proceedings of the 58th Annual Meeting of the Association for Computational Linguistics
Po-Yao Huang | Junjie Hu | Xiaojun Chang | Alexander Hauptmann
Proceedings of the 58th Annual Meeting of the Association for Computational Linguistics
Unsupervised machine translation (MT) has recently achieved impressive results with monolingual corpora only. However, it is still challenging to associate source-target sentences in the latent space. As people speak different languages biologically share similar visual systems, the potential of achieving better alignment through visual content is promising yet under-explored in unsupervised multimodal MT (MMT). In this paper, we investigate how to utilize visual content for disambiguation and promoting latent space alignment in unsupervised MMT. Our model employs multimodal back-translation and features pseudo visual pivoting in which we learn a shared multilingual visual-semantic embedding space and incorporate visually-pivoted captioning as additional weak supervision. The experimental results on the widely used Multi30K dataset show that the proposed model significantly improves over the state-of-the-art methods and generalizes well when images are not available at the testing time.
2019
Multi-Head Attention with Diversity for Learning Grounded Multilingual Multimodal Representations
Po-Yao Huang | Xiaojun Chang | Alexander Hauptmann
Proceedings of the 2019 Conference on Empirical Methods in Natural Language Processing and the 9th International Joint Conference on Natural Language Processing (EMNLP-IJCNLP)
Po-Yao Huang | Xiaojun Chang | Alexander Hauptmann
Proceedings of the 2019 Conference on Empirical Methods in Natural Language Processing and the 9th International Joint Conference on Natural Language Processing (EMNLP-IJCNLP)
With the aim of promoting and understanding the multilingual version of image search, we leverage visual object detection and propose a model with diverse multi-head attention to learn grounded multilingual multimodal representations. Specifically, our model attends to different types of textual semantics in two languages and visual objects for fine-grained alignments between sentences and images. We introduce a new objective function which explicitly encourages attention diversity to learn an improved visual-semantic embedding space. We evaluate our model in the German-Image and English-Image matching tasks on the Multi30K dataset, and in the Semantic Textual Similarity task with the English descriptions of visual content. Results show that our model yields a significant performance gain over other methods in all of the three tasks.
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Co-authors
- Alexander G. Hauptmann 2
- Po-Yao Huang 2
- Haodong Chen 1
- Lei Chen 1
- Weidong Chen 1
- Xiuying Chen 1
- Zilong Chen 1
- Gerard De Melo 1
- Shangbin Feng 1
- Lang Gao 1
- Mingfei Han 1
- Junjie Hu 1
- Qiang Huang 1
- Yuan Huang 1
- Qiuping Jiang 1
- Yuecheng Lei 1
- Yaqing Liao 1
- Sihao Lin 1
- Junchang Liu 1
- Haozhe Luo 1
- Minnan Luo (罗敏楠) 1
- Lizhen Qu 1
- Yazhou Ren 1
- Zirui Song 1
- Zhaoxuan Tan 1
- Chenxi Wang 1
- Ningnan Wang 1
- Zenglin Xu 1
- Zixiang Xu 1
- Mingzhe Yang 1
- Jun Yu 1
- Peisheng Yu 1
- Bairui Zhang 1
- Ruibo Zhang 1
- Jiaqi Zhao 1
- Qinghua Zheng (郑庆华) 1
- Xinyuan Zhu 1
- Terry Yue Zhuo 1