Hardy Chen
Author directoryAlso published as: Guiming Hardy Chen, Guiming Chen
2026
A Comprehensive Analysis for Visual Object Hallucination in Large Vision-Language Models
Liqiang Jing | Hardy Chen | Ehsan Aghazadeh | Xin Eric Wang | Xinya Du
Findings of the Association for Computational Linguistics: EMNLP 2026
Liqiang Jing | Hardy Chen | Ehsan Aghazadeh | Xin Eric Wang | Xinya Du
Findings of the Association for Computational Linguistics: EMNLP 2026
Large Vision-Language Models (LVLMs) demonstrate remarkable capabilities in multimodal tasks, but visual object hallucination remains a persistent issue. It refers to scenarios where models generate inaccurate visual object-related information based on the query input, potentially leading to misinformation and concerns about safety and reliability. Previous works focus on the evaluation and mitigation of visual hallucinations, but the underlying causes have not been comprehensively investigated. In this paper, we analyze each component of LLaVA-like LVLMs—the large language model, the vision backbone, and the projector, to identify potential sources of error and their impact. Based on our observations, we propose methods to mitigate hallucination for each problematic component. Additionally, we developed two hallucination benchmarks: QA-VisualGenome, which emphasizes attribute and relation hallucinations, and QA-FB15k, which focuses on cognition-based hallucinations.
Your Agent, Their Asset: A Real-World Safety Analysis of OpenClaw
Zijun Wang | Haoqin Tu | Letian Zhang | Hardy Chen | Juncheng Wu | Xiangyan Liu | Zhenlong Yuan | Tianyu Pang | Qizhe Xie | Fengze Liu | Zeyu Zheng | Huaxiu Yao | Yuyin Zhou | Cihang Xie
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Zijun Wang | Haoqin Tu | Letian Zhang | Hardy Chen | Juncheng Wu | Xiangyan Liu | Zhenlong Yuan | Tianyu Pang | Qizhe Xie | Fengze Liu | Zeyu Zheng | Huaxiu Yao | Yuyin Zhou | Cihang Xie
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
OpenClaw, the most widely deployed personal AI agent in early 2026, operates with full local system access and integrates with sensitive services such as Gmail, Stripe, and the filesystem. While these broad privileges enable high levels of automation and powerful personalization, they also expose a substantial attack surface that existing sandboxed evaluations fail to capture. To address this gap, we present the first real-world safety evaluation of OpenClaw and introduce the CIK taxonomy, which unifies an agent’s persistent state into three dimensions, i.e., Capability, Identity, and Knowledge, for safety analysis. Our evaluations cover 12 attack scenarios on a live OpenClaw instance across four backbone models (Claude Sonnet 4.5, Opus 4.6, Gemini 3.1 Pro, and GPT-5.4). The results show that poisoning any single CIK dimension increases the average attack success rate from 24.6% to 64-74%, with even the most robust model exhibiting more than a threefold increase over its baseline vulnerability. We further assess three CIK-aligned defense strategies alongside a file-protection mechanism; however, the strongest defense still yields a 63.8% success rate under Capability-targeted attacks, while file protection blocks 97% of malicious injections but also prevents legitimate updates. Taken together, these findings show that the vulnerabilities are inherent to the agent architecture, necessitating more systematic safeguards to secure personal AI agents. Our project page is https://ucsc-vlaa.github.io/CIK-Bench.
Reasoning While Asking: Transforming Reasoning Large Language Models from Passive Solvers to Proactive Inquirers
Xin Chen | Feng Jiang | Yiqian Zhang | Hardy Chen | Shuo Yan | Wenya Xie | Min Yang | Shujian Huang
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Xin Chen | Feng Jiang | Yiqian Zhang | Hardy Chen | Shuo Yan | Wenya Xie | Min Yang | Shujian Huang
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Reasoning-oriented Large Language Models (LLMs) have achieved remarkable progress with Chain-of-Thought (CoT) prompting, yet they remain fundamentally limited by a blind self-thinking paradigm: performing extensive internal reasoning even when critical information is missing or ambiguous. We propose Proactive Interactive Reasoning (PIR), a new reasoning paradigm that transforms LLMs from passive solvers into proactive inquirers that interleave reasoning with clarification. Unlike existing search- or tool-based frameworks that primarily address knowledge uncertainty by querying external environments, PIR targets premise- and intent-level uncertainty through direct interaction with the user. PIR is implemented via two core components: (1) an uncertainty-aware supervised fine-tuning procedure that equips models with interactive reasoning capability, and (2) a user-simulator-based policy optimization framework driven by a composite reward that aligns model behavior with user intent. Extensive experiments on mathematical reasoning, code generation, and document editing demonstrate that PIR consistently outperforms strong baselines, achieving up to 32.70% higher accuracy, 22.90% higher pass rate, and 41.36 BLEU improvement, while reducing nearly half of the reasoning computation and unnecessary interaction turns. Further reliability evaluations on factual knowledge, question answering, and missing-premise scenarios confirm the strong generalization and robustness of PIR.
2025
MLLM-Bench: Evaluating Multimodal LLMs with Per-sample Criteria
Wentao Ge | Shunian Chen | Guiming Hardy Chen | Nuo Chen | Junying Chen | Zhihong Chen | Wenya Xie | Shuo Yan | Chenghao Zhu | Ziyue Lin | Dingjie Song | Xidong Wang | Anningzhe Gao | Zhiyi Zhang | Jianquan Li | Xiang Wan | Benyou Wang
Proceedings of the 2025 Conference of the Nations of the Americas Chapter of the Association for Computational Linguistics: Human Language Technologies (Volume 1: Long Papers)
Wentao Ge | Shunian Chen | Guiming Hardy Chen | Nuo Chen | Junying Chen | Zhihong Chen | Wenya Xie | Shuo Yan | Chenghao Zhu | Ziyue Lin | Dingjie Song | Xidong Wang | Anningzhe Gao | Zhiyi Zhang | Jianquan Li | Xiang Wan | Benyou Wang
Proceedings of the 2025 Conference of the Nations of the Americas Chapter of the Association for Computational Linguistics: Human Language Technologies (Volume 1: Long Papers)
Multimodal large language models (MLLMs) have broadened the scope of AI applications. Existing automatic evaluation methodologies for MLLMs are mainly limited in evaluating objective queries without considering real-world user experiences, inadequately addressing the nuances of creative and associative multimodal tasks. However, the open-ended and subjective nature of such tasks poses a significant challenge to the evaluation methodology, where it is difficult to define the ground-truth answers for them. To this end, in our paper, we propose a new evaluation paradigm for MLLMs, which is evaluating MLLMs with per-sample criteria using potent MLLM as the judge. To validate the feasibility and effectiveness of this paradigm, we design a benchmark, dubbed MLLM-Bench, by curating the evaluation samples across six comprehensive cognitive levels. We benchmark 26 popular MLLMs in a pairwise-comparison fashion, showing diverse performance across models. Moreover, the validity of our benchmark manifests itself in reaching 88.02% agreement with human evaluation. We contend that the proposed paradigm explores the potential of MLLMs as effective evaluation tools with the help of per-sample criteria.
ViLBench: A Suite for Vision-Language Process Reward Modeling
Haoqin Tu | Weitao Feng | Hardy Chen | Hui Liu | Xianfeng Tang | Cihang Xie
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
Haoqin Tu | Weitao Feng | Hardy Chen | Hui Liu | Xianfeng Tang | Cihang Xie
Proceedings of the 2025 Conference on Empirical Methods in Natural Language Processing
Process-supervised reward models serve as a fine-grained function that provides detailed step-wise feedback to model responses, facilitating effective selection of reasoning trajectories for complex tasks. Despite its advantages, evaluation on PRMs remains less explored, especially in the multimodal domain. To address this gap, this paper first benchmarks current vision large language models (VLLMs) as two types of reward models: output reward models (ORMs) and process reward models (PRMs) on multiple vision-language benchmarks, which reveal that neither ORM nor PRM consistently outperforms across all tasks, and superior VLLMs do not necessarily yield better rewarding performance. To further advance evaluation, we introduce ViLBench, a vision-language benchmark designed to require intensive process reward signals. Notably, OpenAI’s GPT-4o with Chain-of-Thought (CoT) achieves only 27.3% accuracy, challenging current VLLMs. Lastly, we preliminarily showcase a promising pathway towards bridging the gap between general VLLMs and reward models—by collecting 73.6K vision-language process reward data using an enhanced tree-search algorithm, our 3B model is able to achieve an average improvement of 3.3% over standard CoT and up to 2.5% compared to its untrained counterpart on ViLBench by selecting OpenAI o1’s generations. We will release our code, model, and data at https://ucsc-vlaa.github.io/ViLBench.
2024
CMB: A Comprehensive Medical Benchmark in Chinese
Xidong Wang | Guiming Hardy Chen | Dingjie Song | Zhiyi Zhang | Zhihong Chen | Qingying Xiao | Feng Jiang | Jianquan Li | Xiang Wan | Benyou Wang | Haizhou Li
Proceedings of the 2024 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies (Volume 1: Long Papers)
Xidong Wang | Guiming Hardy Chen | Dingjie Song | Zhiyi Zhang | Zhihong Chen | Qingying Xiao | Feng Jiang | Jianquan Li | Xiang Wan | Benyou Wang | Haizhou Li
Proceedings of the 2024 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies (Volume 1: Long Papers)
Large Language Models (LLMs) provide a possibility to make a great breakthrough in medicine. The establishment of a standardized medical benchmark becomes a fundamental cornerstone to measure progression. However, medical environments in different regions have their local characteristics, e.g., the ubiquity and significance of traditional Chinese medicine within China. Therefore, merely translating English-based medical evaluation may result in contextual incongruities to a local region. To solve the issue, we propose a localized medical benchmark called CMB, a Comprehensive Medical Benchmark in Chinese, designed and rooted entirely within the native Chinese linguistic and cultural framework. While traditional Chinese medicine is integral to this evaluation, it does not constitute its entirety. Using this benchmark, we have evaluated several prominent large-scale LLMs, including ChatGPT, GPT-4, dedicated Chinese LLMs, and LLMs specialized in the medical domain. We hope this benchmark provide first-hand experience in existing LLMs for medicine and also facilitate the widespread adoption and enhancement of medical LLMs within China. Our data and code are publicly available at https://github.com/FreedomIntelligence/CMB.
More Samples or More Prompts? Exploring Effective Few-Shot In-Context Learning for LLMs with In-Context Sampling
Bingsheng Yao | Guiming Chen | Ruishi Zou | Yuxuan Lu | Jiachen Li | Shao Zhang | Yisi Sang | Sijia Liu | James Hendler | Dakuo Wang
Findings of the Association for Computational Linguistics: NAACL 2024
Bingsheng Yao | Guiming Chen | Ruishi Zou | Yuxuan Lu | Jiachen Li | Shao Zhang | Yisi Sang | Sijia Liu | James Hendler | Dakuo Wang
Findings of the Association for Computational Linguistics: NAACL 2024
While most existing works on LLM prompting techniques focus only on how to select a better set of data samples inside one single prompt input (In-Context Learning or ICL), why can not we design and leverage multiple prompts together to further improve the LLM’s performance? In this work, we propose In-Context Sampling (ICS), a low-resource LLM prompting technique to produce confident predictions by optimizing the construction of multiple ICL prompt inputs. Extensive experiments with three open-source LLMs (FlanT5-XL, Mistral-7B, and Mixtral-8x7B) on four NLI datasets (e-SNLI, Multi-NLI, ANLI, and Contract-NLI) and one QA dataset (CommonsenseQA) illustrate that ICS can consistently enhance LLMs’ performance. An in-depth evaluation with three data similarity-based ICS strategies suggests that these strategies can further elevate LLM’s performance, which sheds light on a new yet promising future research direction.
Humans or LLMs as the Judge? A Study on Judgement Bias
Guiming Hardy Chen | Shunian Chen | Ziche Liu | Feng Jiang | Benyou Wang
Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing
Guiming Hardy Chen | Shunian Chen | Ziche Liu | Feng Jiang | Benyou Wang
Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing
Adopting human and large language models (LLM) as judges (a.k.a human- and LLM-as-a-judge) for evaluating the performance of LLMs has recently gained attention. Nonetheless, this approach concurrently introduces potential biases from human and LLMs, questioning the reliability of the evaluation results. In this paper, we propose a novel framework that is free from referencing groundtruth annotations for investigating Misinformation Oversight Bias, Gender Bias, Authority Bias and Beauty Bias on LLM and human judges. We curate a dataset referring to the revised Bloom’s Taxonomy and conduct thousands of evaluations. Results show that human and LLM judges are vulnerable to perturbations to various degrees, and that even the cutting-edge judges possess considerable biases. We further exploit these biases to conduct attacks on LLM judges. We hope that our work can notify the community of the bias and vulnerability of human- and LLM-as-a-judge, as well as the urgency of developing robust evaluation systems.
Towards Injecting Medical Visual Knowledge into Multimodal LLMs at Scale
Junying Chen | Chi Gui | Ruyi Ouyang | Anningzhe Gao | Shunian Chen | Guiming Hardy Chen | Xidong Wang | Zhenyang Cai | Ke Ji | Xiang Wan | Benyou Wang
Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing
Junying Chen | Chi Gui | Ruyi Ouyang | Anningzhe Gao | Shunian Chen | Guiming Hardy Chen | Xidong Wang | Zhenyang Cai | Ke Ji | Xiang Wan | Benyou Wang
Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing
The rapid development of multimodal large language models (MLLMs), such as GPT-4V, has led to significant advancements. However, these models still face challenges in medical multimodal capabilities due to limitations in the quantity and quality of medical vision-text data, stemming from data privacy concerns and high annotation costs. While pioneering approaches utilize PubMed’s large-scale, de-identified medical image-text pairs to address these limitations, they often fall short due to inherent data noise. To tackle this, we refined medical image-text pairs from PubMed and employed MLLMs (GPT-4V) in an ‘unblinded’ capacity to denoise and reformat the data, resulting in the creation of the PubMedVision dataset with 1.3 million medical VQA samples. Our validation demonstrates that: (1) PubMedVision can significantly enhance the medical multimodal capabilities of MLLMs, showing significant improvement in benchmarks including the MMMU Health & Medicine track; (2) manual checks by medical experts and empirical results validate the superior data quality of our dataset compared to other data construction methods. Using PubMedVision, we train a 34B medical MLLM HuatuoGPT-Vision, which shows superior performance in medical multimodal scenarios among open-source MLLMs. Our code and data are available at https://github.com/FreedomIntelligence/HuatuoGPT-Vision.
2023
HuatuoGPT, Towards Taming Language Model to Be a Doctor
Hongbo Zhang | Junying Chen | Feng Jiang | Fei Yu | Zhihong Chen | Jianquan Li | Guiming Chen | Xiangbo Wu | Zhiyi Zhang | Qingying Xiao | Xiang Wan | Benyou Wang | Haizhou Li
Findings of the Association for Computational Linguistics: EMNLP 2023
Hongbo Zhang | Junying Chen | Feng Jiang | Fei Yu | Zhihong Chen | Jianquan Li | Guiming Chen | Xiangbo Wu | Zhiyi Zhang | Qingying Xiao | Xiang Wan | Benyou Wang | Haizhou Li
Findings of the Association for Computational Linguistics: EMNLP 2023
In this paper, we present HuatuoGPT, a Large Language Model (LLM) for medical consultation. The core recipe of HuatuoGPT is to leverage both distilled data from ChatGPT and real-world data from doctors in the supervised fine-tuning stage. This is not only because purely using ChatGPT-distilled data might cause ‘model collapse’, but also because real-world data from doctors would be complementary to ChatGPT-distilled data. The responses from ChatGPT are usually detailed, well-presented, fluent, and instruction-followed, but it cannot perform like a doctor in many aspects, e.g. for interactive diagnosis. Therefore, the extra doctors’ data could tame a distilled language model to perform like doctors. To synergize the strengths of both data sources, we introduce RLMF (Reinforcement Learning from Mixed Feedback) where a reward model is trained to align the language model with the merits that both sources (ChatGPT and doctors) bring. Experimental results (in GPT-4 evaluation, human evaluation, and medical benchmark datasets) demonstrate that HuatuoGPT achieves state-of-the-art results in performing medical consultation among open-source LLMs. It is worth noting that by using additional real-world data and RLMF, the distilled language model (i.e., HuatuoGPT) outperforms its teacher model (i.e., ChatGPT) in most cases.
On the Difference of BERT-style and CLIP-style Text Encoders
Zhihong Chen | Guiming Hardy Chen | Shizhe Diao | Xiang Wan | Benyou Wang
Findings of the Association for Computational Linguistics: ACL 2023
Zhihong Chen | Guiming Hardy Chen | Shizhe Diao | Xiang Wan | Benyou Wang
Findings of the Association for Computational Linguistics: ACL 2023
Masked language modeling (MLM) has been one of the most popular pretraining recipes in natural language processing, e.g., BERT, one of the representative models. Recently, contrastive language-image pretraining (CLIP) has also attracted attention, especially its vision models that achieve excellent performance on a broad range of vision tasks. However, few studies are dedicated to studying the text encoders learned by CLIP. In this paper, we analyze the difference between BERT-style and CLIP-style text encoders from three experiments: (i) general text understanding, (ii) vision-centric text understanding, and (iii) text-to-image generation. Experimental analyses show that although CLIP-style text encoders underperform BERT-style ones for general text understanding tasks, they are equipped with a unique ability, i.e., synesthesia, for the cross-modal association, which is more similar to the senses of humans.
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- Benyou Wang 6
- Xiang Wan 5
- Zhihong Chen 4
- Feng Jiang (蒋峰) 4
- Junying Chen 3
- Shunian Chen 3
- Jianquan Li 3
- Xidong Wang 3
- Zhiyi Zhang 3
- Anningzhe Gao 2
- Haizhou Li 2
- Dingjie Song 2
- Haoqin Tu 2
- Qingying Xiao 2
- Cihang Xie 2
- Wenya Xie 2
- Shuo Yan 2
- Ehsan Aghazadeh 1
- Zhenyang Cai 1
- Nuo Chen 1
- Xin Chen 1
- Shizhe Diao 1
- Xinya Du 1
- Weitao Feng 1
- Wentao Ge 1
- Chi Gui 1
- James Hendler 1
- Shujian Huang (书剑 黄) 1
- Ke Ji 1
- Liqiang Jing 1
- Jiachen Li 1
- Ziyue Lin 1
- Fengze Liu 1
- Hui Liu 1
- Sijia Liu 1
- Xiangyan Liu 1
- Ziche Liu 1
- Yuxuan Lu 1
- Ruyi Ouyang 1
- Tianyu Pang 1
- Yisi Sang 1
- Xianfeng Tang 1
- Dakuo Wang 1
- Xin Eric Wang 1
- Zijun Wang 1
- Juncheng Wu 1
- Xiangbo Wu 1
- Qizhe Xie 1
- Min Yang 1
- Bingsheng Yao 1
- Huaxiu Yao 1
- Fei Yu 1
- Zhenlong Yuan 1
- Hongbo Zhang 1
- Letian Zhang 1
- Shao Zhang 1
- Yiqian Zhang 1
- Zeyu Zheng 1
- Yuyin Zhou 1
- Chenghao Zhu 1
- Ruishi Zou 1