Yijiang Li
2026
Vision-Language Models Mistake Head Orientation for Gaze Direction: Nonverbal Conversation Cues
Zory Zhang | Pinyuan Feng | Bingyang Wang | Tianwei Zhao | Suyang Yu | Qingying Gao | Hokin Deng | Ziqiao Ma | Yijiang Li | Dezhi Luo
Findings of the Association for Computational Linguistics: ACL 2026
Zory Zhang | Pinyuan Feng | Bingyang Wang | Tianwei Zhao | Suyang Yu | Qingying Gao | Hokin Deng | Ziqiao Ma | Yijiang Li | Dezhi Luo
Findings of the Association for Computational Linguistics: ACL 2026
Where someone looks is a nonverbal communication cue that children and adults readily use.How well can Vision-Language Models (VLMs) infer gaze targets? To construct evaluation stimuli, we captured 1,360 real-world photos of scenes in which a person gazes at one of several objects on a table. Importantly, we also controlled the gazer’s head orientation: sometimes it was directed toward the gaze target, sometimes toward a distractor object, and sometimes left unconstrained. We found a substantial performance gap between VLMs and humans, ruled out alternative explanations such as resolution and object-naming skills, and identified the main reason for the gap as VLMs inferring gaze direction using head orientation rather than eye appearance.Such a bias is likely due to data rather than architecture, as suggested by a proof-of-concept experiment finetuning a transformer-based vision model.Future work should investigate whether these findings hold broadly across various deep learning methods trained on existing data, and whether better data mitigates this problem for all architectures.Pinpointing the reason sets the stage for technologies that can interpret gaze targets to have more efficient interactions with humans.
2025
FedSpaLLM: Federated Pruning of Large Language Models
Guangji Bai | Yijiang Li | Zilinghan Li | Liang Zhao | Kibaek Kim
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)
Guangji Bai | Yijiang Li | Zilinghan Li | Liang Zhao | Kibaek Kim
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)
Large Language Models (LLMs) achieve state-of-the-art performance but are challenging to deploy due to their high computational and storage demands. Pruning can reduce model size, yet existing methods assume public access to calibration data, which is impractical for privacy-sensitive applications. To address the challenge of pruning LLMs in privacy-preserving settings, we propose FedSpaLLM, the first federated learning framework designed specifically for pruning LLMs. FedSpaLLM enables clients to locally prune their models based on private data while accounting for system heterogeneity and maintaining communication efficiency. Our framework introduces several key innovations: (1) a novel ℓ0-norm aggregation function that ensures only non-zero weights are averaged across clients, preserving important model parameters; (2) an adaptive mask expansion technique that meets global sparsity targets while accommodating client-specific pruning decisions; and (3) a layer sampling strategy that reduces communication overhead and personalizes the pruning process based on client resources. Extensive experiments show that FedSpaLLM improves pruning performance in diverse federated settings.
Jailbreaking Prompt Attack: A Controllable Adversarial Attack against Diffusion Models
Jiachen Ma | Yijiang Li | Zhiqing Xiao | Anda Cao | Jie Zhang | Chao Ye | Junbo Zhao
Findings of the Association for Computational Linguistics: NAACL 2025
Jiachen Ma | Yijiang Li | Zhiqing Xiao | Anda Cao | Jie Zhang | Chao Ye | Junbo Zhao
Findings of the Association for Computational Linguistics: NAACL 2025
Text-to-image (T2I) models can be maliciously used to generate harmful content such as sexually explicit, unfaithful, and misleading or Not-Safe-for-Work (NSFW) images. Previous attacks largely depend on the availability of the diffusion model or involve a lengthy optimization process. In this work, we investigate a more practical and universal attack that does not require the presence of a target model and demonstrate that the high-dimensional text embedding space inherently contains NSFW concepts that can be exploited to generate harmful images. We present the Jailbreaking Prompt Attack (JPA). JPA first searches for the target malicious concepts in the text embedding space using a group of antonyms generated by ChatGPT. Subsequently, a prefix prompt is optimized in the discrete vocabulary space to align malicious concepts semantically in the text embedding space.We further introduce a soft assignment with gradient masking technique that allows us to perform gradient ascent in the discrete vocabulary space.We perform extensive experiments with open-sourced T2I models, e.g. stable-diffusion-v1-4 and closed-sourced online services, e.g. DALL·E 2 and Midjourney with black-box safety checkers. Results show that (1) JPA bypasses both text and image safety checkers, (2) while preserving high semantic alignment with the target prompt. (3) JPA demonstrates a much faster speed than previous methods and can be executed in a fully automated manner. These merits render it a valuable tool for robustness evaluation in future text-to-image generation research.