Direct Language Model Alignment from Online AI Feedback
Authors: name: Shangmin Guo; name: Biao Zhang; name: Tianlin Liu; name: Tianqi Liu; name: Misha Khalman; name: Felipe Llinares; name: Alexandre Rame; name: Thomas Mesnard; name: Yao Zhao; name: Bilal Piot; name: Johan Ferret; name: Mathieu Blondel
Published: 2024-02-07 12:31:13

Abstract: Direct alignment from preferences (DAP) methods, such as DPO, have recently
emerged as efficient alternatives to reinforcement learning from human feedback
(RLHF), that do not require a separate reward model. However, the preference
datasets used in DAP methods are usually collected ahead of training and never
updated, thus the feedback is purely offline. Moreover, responses in these
datasets are often sampled from a language model distinct from the one being
aligned, and since the model evolves over training, the alignment phase is
inevitably off-policy. In this study, we posit that online feedback is key and
improves DAP methods. Our method, online AI feedback (OAIF), uses an LLM as
annotator: on each training iteration, we sample two responses from the current
model and prompt the LLM annotator to choose which one is preferred, thus
providing online feedback. Despite its simplicity, we demonstrate via human
evaluation in several tasks that OAIF outperforms both offline DAP and RLHF
methods. We further show that the feedback leveraged in OAIF is easily
controllable, via instruction prompts to the LLM annotator.