Catarina G Belem

I am a final-year PhD student in Computer Science at the University of California, Irvine, advised by Sameer Singh and Padhraic Smyth. I also collaborate with Mark Steyvers in UCI’s Department of Cognitive Sciences. Broadly, my research asks how we can make language models more reliable and trustworthy in real-world settings.

My work has two main directions. First, I evaluate model failures, including gender bias, hallucinations, uncertainty quantification, and uncertainty communication. Second, I study ways to control model behavior, using both decoding-time and training-time methods to make language models better aligned with human preferences, values, and needs.

During my PhD, I have been fortunate to complete research internships at Megagon Labs, Capital One, and Apple, where I worked on LLM evaluation, factual and readable generation, model customization, and reasoning.

Before my PhD, I was a research data scientist at Feedzai, working with Pedro Saleiro and Pedro Bizarro in the Responsible AI group. There, I worked on algorithmic fairness and explainable AI for fraud detection.

News

Jun 2026 Excited to start a research internship at Apple, working on post-training recipes to improve the QA system powering Siri! πŸ™Œ
Jun 2026 Honored to be interviewed for the Deep Learning Voices hosted by the Deep Learning Sessions Portugal (remote)! πŸ₯‚
May 2026 New preprint out β€” Certainty Distortion in Language Model Rewriting! 🌟
Jan 2026 Our paper Uncertainty as Feature Gaps was accepted at ICLR 2026! πŸŽ‰
Jan 2026 Excited to TA CS 175 β€” Projects in AI (Winter 2026), where I’ll mentor students building NLP-related projects! πŸ™Œ
Dec 2025 Our paper Bayesian Evaluation of Black-box LLM Behavior was accepted at the NeurIPS 2025 LLM Evaluations Workshop! πŸŽ‰
Dec 2025 Our paper Semantic Probabilistic Control of Language Models was accepted at the NeurIPS 2025 SPIGM Workshop! πŸŽ‰
Nov 2025 Our paper Readability Reconsidered was accepted at the TSAR Workshop @ EMNLP 2025! πŸŽ‰
Jun 2025 Excited to start a research internship at Capital One, working on post-training recipes for question-answering systems! πŸ™Œ
Apr 2025 Our paper on hallucination in multi-document summarization was accepted at NAACL 2025 Findings! πŸŽ‰
Apr 2025 Gave an invited talk at the Mila/McGill NLP reading group on perceptions of linguistic uncertainty! 🎊
Mar 2025 New preprint out β€” Semantic Probabilistic Control of Language Models! 🌟
Jan 2025 Our paper on what large language models know and what people think they know was published in Nature Machine Intelligence! πŸŽ‰
Nov 2024 Our paper Perceptions of Linguistic Uncertainty was accepted at EMNLP 2024! πŸŽ‰
Jun 2024 Excited to start a research internship at Megagon Labs, working on evaluating, characterizing, and mitigating hallucinations in multi-document summarization! πŸ™Œ