Weak-To-Strong Generalization: Eliciting Strong Capabilities With Weak Supervision

AI Safety Fundamentals: Alignment

Widely used alignment techniques, such as reinforcement learning from human feedback (RLHF), rely on the ability of humans to supervise model behavior—for example, to evaluate whether a model faithfully followed instructions or generated safe outputs. However, future superhuman models will behave in complex ways too difficult for humans to reliably evaluate; humans will only be able to weakly supervise superhuman models. We study an analogy to this problem: can weak model supervision elicit the full capabilities of a much stronger model? We test this using a range of pretrained language models in the GPT-4 family on natural language processing (NLP), chess, and reward modeling tasks. We find that when we naively fine-tune strong pretrained models on labels generated by a weak model, they consistently perform better than their weak supervisors, a phenomenon we call weak-to-strong generalization. However, we are still far from recovering the full capabilities of strong models with naive fine-tuning alone, suggesting that techniques like RLHF may scale poorly to superhuman models without further work.

We find that simple methods can often significantly improve weak-to-strong generalization: for example, when fine-tuning GPT-4 with a GPT-2-level supervisor and an auxiliary confidence loss, we can recover close to GPT-3.5-level performance on NLP tasks. Our results suggest that it is feasible to make empirical progress today on a fundamental challenge of aligning superhuman models.

Source:
https://arxiv.org/pdf/2312.09390.pdf
Narrated for AI Safety Fundamentals by Perrin Walker

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