Training language models to follow instructions with human feedback

Making language models bigger does not inherently make them better at following a user’s intent. For example, large language models can generate outputs that are untruthful, toxic, or simply not helpful to the user. In other words, these models are not aligned with their users. In this paper, we show an avenue for aligning language models with user intent on a wide range of tasks by fine-tuning with human feedback. Starting with a set of labeler-written prompts and prompts submitted through the OpenAI API, we collect a dataset of labeler demonstrations of the desired model behavior, which we use to fine-tune GPT-3 using supervised learning. We then collect a dataset of rankings of model outputs, which we use to further fine-tune this supervised model using reinforcement learning from human feedback. We call the resulting models InstructGPT. In human evaluations on our prompt distribution, outputs from the 1.3B parameter InstructGPT model are preferred to outputs from the 175B GPT-3, despite having 100x fewer parameters. Moreover, InstructGPT models show improvements in truthfulness and reductions in toxic output generation while having minimal performance regressions on public NLP datasets.

Introduction. Large language models (LMs) can be “prompted” to perform a range of natural language processing (NLP) tasks, given some examples of the task as input. However, these models often express unintended behaviors such as making up facts, generating biased or toxic text, or simply not following user instructions (Bender et al., 2021; Bommasani et al., 2021; Kenton et al., 2021; Weidinger et al., 2021; Tamkin et al., 2021; Gehman et al., 2020). This is because the language modeling objective used for many recent large LMs—predicting the next token on a webpage from the internet—is different from the objective “follow the user’s instructions helpfully and safely” (Radford et al., 2019; Brown et al., 2020; Fedus et al., 2021; Rae et al., 2021; Thoppilan et al., 2022). Thus, we say that the language modeling objective is misaligned. Averting these unintended behaviors is especially important for language models that are deployed and used in hundreds of applications.

Discussion / Conclusion. This research is part of our broader research program to align AI systems with human intentions (Christiano et al., 2017; Ziegler et al., 2019; Stiennon et al., 2020). Even though this work focuses on our current language model systems, we seek general and scalable methods that work for future AI systems (Leike et al., 2018). The systems we work with here are still fairly limited, but they are among the largest language models today and we apply them on a wide range of language tasks, including classification, summarization, question-answering, creative writing, dialogue, and others. Our approach to alignment research in this work is iterative: we are improving the alignment of current AI systems instead of focusing abstractly on aligning AI systems that don’t yet exist. A disadvantage of this approach is that we are not directly facing alignment problems that occur only when aligning superhuman systems (Bostrom, 2014). However, our approach does provides us with a clear empirical feedback loop of what works and what does not.