Jonathan Uesato
Jonathan Uesato is an AI researcher whose work spans robust machine learning, language-model safety and AI alignment. At DeepMind, he coauthored research on adversarial robustness and specification gaming, then studied toxicity controls and feedback for mathematical reasoning. He left OpenAI in 2024 and later coauthored studies of chain-of-thought faithfulness and alignment faking, while mentoring Anthropic research on reward hacking. As of October 2026, he is a member of technical staff at Anthropic and supports research into reward seeking during reinforcement learning.
- Now at
- Anthropic
Timeline
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2019
Robust learning at DeepMind
In 2019, he works in DeepMind's Robust and Verified Deep Learning group and coauthors a study showing that unlabeled data can be a competitive alternative for training adversarially robust models.
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2020
Specification gaming
In 2020, he coauthors Google DeepMind's essay defining specification gaming as meeting an objective's literal specification without achieving its intended outcome.
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2021
Detoxifying language models
In 2021, he coauthors research on detoxifying language models. It finds that basic toxicity interventions can improve automatic toxicity metrics while reducing coverage of texts about marginalized groups and their dialects.
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2022
Process feedback for math
In 2022, he coauthors a comparison of process- and outcome-based feedback for math word problems. It finds that correct reasoning steps require process-based supervision or learned reward models that emulate it.
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2024
Leaving OpenAI
In 2024, he leaves OpenAI as one of several departures from its AGI-safety staff.
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January 2025–May 2025
Reward hacking and faithfulness
In January 2025, he mentors an Anthropic study showing that training on documents about reward hacking can increase or decrease the behavior. In May 2025, he coauthors a study of chain-of-thought faithfulness; it finds that the reveal rate for hints is often below 20% in many settings.
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December 2025
Alignment faking mitigations
In December 2025, he coauthors Anthropic research testing black-box interrogation, scratchpad length penalties and process supervision as training-time mitigations for alignment faking.
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As of October 2026
Member of technical staff
In August 2026, Anthropic thanks him for discussion and support on its study of a reward seeker trained through reinforcement learning. As of October 2026, he is a member of technical staff at Anthropic.
Career
Sources and credits
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- Identifying and eliminating bugs in learned predictive models
- Are Labels Required for Improving Adversarial Robustness?
- Specification gaming: the flip side of AI ingenuity
- Jonathan Uesato - ACL Anthology
- Solving math word problems with process- and outcome-based feedback
- Exodus at OpenAI: Nearly half of AGI safety staffers have left, says former researcher
- Training on Documents About Reward Hacking Induces Reward Hacking
- Reasoning Models Don't Always Say What They Think
- Towards training-time mitigations for alignment faking in RL
- Training a Misaligned Reward Seeker
- Lab Employee Statement on Extreme AI Risks