Sitong Fang

Undergraduate Student, Yuanpei College, Peking University

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I am a senior undergraduate majoring in Artificial Intelligence at Yuanpei College, Peking University, advised by Prof. Yaodong Yang. I am a member of the PKU Alignment Group and a Research Scientist at Physis AI.

My research focuses on trustworthy multimodal AI and physically grounded world models. I have introduced TruthfulVQA (ACL 2026), the first benchmark for multimodal truthfulness, and Debate with Images (preprint, 2025), a visually grounded multi-agent debate framework for detecting deception in multimodal LLMs, along with MM-DeceptionBench, the first benchmark for multimodal deception. I am also a co-first author of the AI Deception Survey, the first systematic international survey on AI deception, with Turing Award laureate Andrew Yao as corresponding author.

News

  • 2026.04   One paper accepted at ACL 2026.
  • 2025.11   Our survey AI Deception released, the first systematic international report on AI deception, with Turing Award laureate Andrew Yao as the corresponding author.
  • 2026.09   Debate with Images released, introducing MM-DeceptionBench and a multi-agent debate framework for multimodal deception detection.
  • 2025.06   Eval-Anything open-sourced at PKU-Alignment. Debate with Images released, introducing MM-DeceptionBench and a multi-agent debate framework for multimodal deception detection.
  • 2025.05   Awarded Beijing Natural Science Foundation Undergraduate QiYan Research Program Grant.

Honors and Awards

  • 2025   Yuanpei Young Scholar (10 annual recipients)
  • 2025   Beijing Natural Science Foundation Undergraduate QiYan Research Program (Sole recipient in the cohort)
  • 2025   Soong Ching Ling Future Scholarship (national undergraduate scholarship)
  • 2024   Peking University Boya Scholarship
  • 2024   Peking University Academic Excellence Award, Social Service Award
  • 2023   Peking University Freshman Scholarship (First Prize)
  • 2023   Ranked 1st in Fujian Province, National College Entrance Exam (Science)

Selected Publications

2026

  1. When Slower Isn’t Truer: Inverse Scaling Law of Truthfulness in Multimodal Reasoning
    Sitong Fang , Wenjing Cao , Jiahao Li , 5 more authors Yaodong Yang, and Jiaming Ji
    In Proceedings of the Annual Meeting of the Association for Computational Linguistics (ACL), 2026
  2. Under Review
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    Debate with Images: Detecting Deceptive Behaviors in Multimodal Large Language Models
    Sitong Fang , Shiyi Hou , Kaile Wang , 4 more authors Yaodong Yang, and Jiaming Ji
    Under Review at the International Conference on Machine Learning (ICML), 2026

2025

  1. Under Review
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    AI Deception: Risks, Dynamics, and Controls
    Boyuan Chen* , Sitong Fang* , Jiaming Ji* , 51 more authors Yaodong Yang, Tiejun Huang, Ya-Qin Zhang, HongJiang Zhang, and Andrew Yao
    Under Review at ACM Computing Surveys, 2025

Experiences

Physis AI (逆矩阵科技) · Research Scientist · 2026.02 – Present
Building physically grounded world foundation models with reinforcement learning.
PKU-Alignment Group, Peking University · Research Intern · 2024.12 – Present
  • Core contributor to Align-Anything (4k+ ★): All-modality alignment framework
  • Core contributor to Eval-Anything: All-modality safety evaluation framework
HKGAI R&D Center / HKUST · Research Intern · 2024.12 – 2025.03
Contributed to HKGAI-V1, the Hong Kong government's first locally fine-tuned generative AI model, focusing on safety alignment for Cantonese, Mandarin, and English.

Educations

  • 2023 - Present   B.S. in Artificial Intelligence, Yuanpei College, Peking University