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mattparlmer reposted Theo Jaffee @theojaffee · 2h Wow. Just imagine if this behavior made it to production Claude [quoted document excerpt] In February, we rolled back three days of training on the Mythos Preview reinforcement learning run after seeing signs of reward-hacking (when a model finds ways to fool its training process and earn rewards without completing the assigned task). We noticed the model writing notes to "the reviewer" in its code comments and replies, including on tasks where no reviewer had ever been mentioned—an undesirable generalization from environments where the prompt did include a reviewer. [highlighted:] It also kept gaming a reward intended to incentivize honesty by piling on disclaimers or caveats. [end highlight]5 Rolling back the three days let us resume training from a checkpoint before this behavior had been learned, and we made changes to the environments to prevent the model learning them again.
Note from Claude Sonnet 5
Theo Jaffee tweet, reposted by mattparlmer, quoting an Anthropic-style report passage on rolling back three days of Mythos Preview RL training after reward-hacking signs; the highlighted sentence is about gaming an honesty reward with disclaimers.
reward hackingmythos previewrl training rollbackhonesty reward