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Maarten Sap

I am an assistant professor at CMU's LTI department with a courtesy appointment in HCII, and a part-time research scientist and AI safety lead at the Allen Institute for AI (AI2). My research focuses on (1) measuring and improving AI systems' social and interactional intelligence, (2) assessing and combatting social inequality, safety risks, and socio-cultural biases in human- or AI-generated language, and (3) building narrative language technologies for prosocial outcomes. I was named a 2025 Packard Fellow and a recipient of the 2025 Okawa Research Award.

I received my PhD from the University of Washington where I was advised by Noah Smith and Yejin Choi.
[bio for talks]

Recent updates:

December 2025 🏅📃: Very excited to have our paper Artificial Hivemind: The Open-Ended Homogeneity of Language Models (and Beyond) selected for a Best Paper Award at NeurIPS 2025 (Datasets and Benchmarks Track)!! Huge congrats to the first author Liwei Jiang!!!

November 2025 💎🚀: Honored to be a Spring 2025 recipient of the Amazon Research Award for our project on measuring AI agentic safety!

October 2025 🏅⭐: I’m super excited and grateful to announce that I'm part of the 2025 class of Packard Fellows. The Packard Foundation and this fellowship will allow me to explore exciting research directions towards culturally responsible and safe AI 🌍🌈

October 2025 🔍🧑‍🎓: Due to my lab being quite full already, I'm not taking looking for any new students in this upcoming PhD application cycle 😟.

October 2025 🇨🇦🎉: Excited to be attending COLM 2025 in Montreal this October! I'll be giving a talk at the Social Sim Workshop on Unlocking Social Intelligence in AI agents. I'm also thrilled that five papers I co-authored will be presented by my amazing collaborators at COLM: HAICOSYSTEM: An Ecosystem for Sandboxing Safety Risks in Human-AI Interactions (led by Xuhui Zhou et al.), ALFA: Aligning LLMs to Ask Good Questions: A Case Study in Clinical Reasoning (co-led by Jimin Mun et al.), PolyGuard: A Multilingual Safety Moderation Tool for 17 Languages, Fluid Language Model Benchmarking, and The Delta Learning Hypothesis: Preference Tuning on Weak Data can Yield Strong Gains.

August 2025 🌟: Incredibly honored to be one of 7 US recipients of the 2025 Okawa Research Grant from the Okawa Foundation!

August 2025 🧑‍🎓: Welcoming my first postdoc, Vasudha Varadarajan, to the lab!

[older news]

My research group:

Dan Chechelnitsky

CMU Portugal LTI PhD student
co-advised with Chrysoula Zerva

Joel Mire

LTI PhD student

Karina Halevy

LTI PhD student
co-advised with Mona Diab

Jimin Mun

LTI PhD student

Jocelyn Shen

MIT PhD student
co-advised with Cynthia Breazeal

Kynnedy Smith

HCII PhD student
co-advised with Motahhare Eslami

Vasudha Varadarajan

LTI Postdoc

Akhila Yerukola

LTI PhD student

Mingqian Zheng

LTI PhD student
co-advised with Carolyn Rosé

Xuhui Zhou

LTI PhD student

Overarching Research Themes

Themes extracted and images generated with the OpenAI API; there may be inconsistencies.

Ethics and Responsible AI

My research group explores the ethical dimensions of AI interactions, focusing on safety, bias, and societal impacts. One significant paper is the **OpenAgentSafety** framework, which provides comprehensive guidelines for evaluating the safety of AI agents in real-world contexts ([read more](https://arxiv.org/abs/2507.06134)). Another important contribution is **PluriHarms**, which benchmarks human judgments on the spectrum of AI harm, addressing diverse perspectives in AI ethics ([read more](https://arxiv.org/abs/2601.08951)). We also examine user perceptions of AI, as seen in the study, **Let Them Down Easy!**, which discusses the effects of AI guardrails on user preferences ([read more](https://arxiv.org/abs/2506.00195)).

Narrative Analysis and Empathy

My research group explores the profound impact of narratives on human understanding and emotional engagement. We delve into the concept of contextual reasoning in narratives with the paper **Social Story Frames**, which addresses narrative intent and reception in social contexts ([read more](https://arxiv.org/abs/2512.15925)). Another notable study is **HEART-felt Narratives**, which traces the interplay between empathy and narrative style in personal stories, enhancing our understanding of narrative influence ([read more](https://arxiv.org/abs/2405.17633)). Furthermore, we investigate the modeling of empathic similarity through personal narratives in the paper **Modeling Empathic Similarity in Personal Narratives** ([read more](https://arxiv.org/abs/2305.14246)).

AI Agents and Social Intelligence

My research group explores the development of AI agents with advanced social intelligence capabilities. Key work in this area includes **SOTOPIA**, an interactive evaluation framework designed for assessing social intelligence in language agents ([read more](https://arxiv.org/abs/2310.11667)). Another important paper, **SoMi-ToM**, evaluates multi-perspective theory of mind in social interactions, helping AI agents understand complex social cues better ([read more](https://arxiv.org/abs/2506.23046)). Additionally, our study on **Cognitive Chain-of-Thought** introduces structured multimodal reasoning about social situations to improve social comprehension in AI ([read more](https://arxiv.org/abs/2507.20409)).

Language Modelling and Its Challenges

My research group explores the intricacies and challenges of language modeling, particularly regarding biases and performance consistency. The paper **Out of Style** highlights the vulnerability of retrieval-augmented generation models to linguistic variation, emphasizing the need for robustness in language models ([read more](https://arxiv.org/abs/2504.08231)). We also contribute to understanding AI rationality with the **Martingale Score**, an unsupervised metric that evaluates Bayesian reasoning in LLMs ([read more](https://arxiv.org/abs/2512.02914)). Moreover, the work on **PolyGuard** presents a multilingual safety moderation tool, crucial for managing toxic language across different languages ([read more](https://arxiv.org/abs/2504.04377)).

More about me