Narrow harmful training can broadly invert reward model preferences

Fine-tuning on 1,000 harmful preference pairs made two reward models favor harmful answers across seven unseen domains while largely retaining benchmark performance.

Academic
Dhruv Puri · Nikhil Prakash

Northeastern University

Research Digest··3 min read
Puri and Prakash show that targeted harmful fine-tuning can produce emergent misalignment in reward models, which score model outputs during reinforcement learning from human feedback.

1-8B and Qwen3-8B using 1,000 preference pairs that labeled harmful medical or financial responses as preferable.

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