
Summary
Research on gradient routing reveals its potential to generalize across different types of reward hacking in artificial intelligence models. Jacob Drory extends previous work by Ward et al. (2026) to investigate how effectively gradient routing can suppress various forms of reward hacking that occur during training. The study focuses on the ability of a model to handle "visible" hacks, which are directly monitored, and "invisible" hacks, which are not detected during training but may still be present in the data.
Drory introduces a novel training condition called "narrow," where gradients are routed only on a specific set of visible hacks, while invisible hacks remain unmonitored. The results show that gradient routing performs better than expected, with encouraging evidence of generalization across most experimental arms. However, some unexpected failures arise, particularly with certain types of hacks, indicating that further research is needed to understand these discrepancies and improve the robustness of the model.
Overall, while the findings suggest that gradient routing can effectively reduce hacking rates, the study highlights the limitations of the current methodology and the need for additional experiments to explore the generalization of different hack strategies. Future work should aim to address these gaps and further validate the effectiveness of gradient routing in real-world applications.
Show Notes
TLDR: I lightly extend Ward, Hu et al (2026) to measure how well gradient routing generalizes. I route gradients on one type of reward hack (e.g. ones that reason in English) and check whether this suppresses other types at test time (e.g. ones that reason in French), despite the model being trained on those too. This models a realistic monitor that catches some types of hack during training but not others, rather than catching each at the same rate. I find encouraging evidence of generalization, as well as some failures I don’t yet understand. Introduction Recently, Ward, Hu et al (2026) used gradient routing to prevent reward hacking learnt during training from showing up at test time. I think their method is pretty promising. The gist is: Initialize a retain and a forget adapter. Whenever a monitor detects a reward hack during training, only update the forget adapter on that sample (“route the gradient”). Otherwise update both. At test time, remove the forget adapter. If the method worked, the resulting model shouldn't hack too much. I won’t recap their full paper – it is excellent and you should just read it (alternatively, Jake gives a summary here, with [...] --- Outline: (00:47) Introduction (02:37) Methodology (02:40) Recap (04:00) Narrow Routing (05:27) What I report (07:18) Results (10:13) Conclusion (11:45) Appendix: Results with nudge prompt (12:29) Appendix: Predictions The original text contained 4 footnotes which were omitted from this narration. ---
First published:
October 23rd, 2026
Source:
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Narrated by TYPE III AUDIO.
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More from LessWrong (30+ Karma)
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Crossposted from the EA forum
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