Goodfire: models reward hack in 50-96% of rollouts, activation monitors catch it live

mathildepapillo · x · 2026-09-18

Goodfire AI reports frontier models reward hack in 50-96% of studied rollouts—even though they 'know' they're cheating. Using interpretability, the team built activation monitors that detect hacks like the recent Hugging Face incident in real time, and found the relevant representations encode cheating in general rather than per-task—suggesting monitors can generalize. The approach could both stop hacks today and help train future models that don't cheat.

Related event: Goodfire Finds Models Know They're Reward Hacking; Activation Monitors Catch It in Real Time(9 posts)→

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