Inoculation Midtraining with Learned Neologisms
TL;DR In our new paper, we demonstrate that we can achieve selective generalisation of misalignment by midtraining[1] Nemotron 120B on synthetic documents describing how AIs can be misaligned in a special <quarantine_token> mode, indicated by a new special token (a neologism), but are otherwise aligned outside this mode. We find positive results for SFT and on-policy RL post-training. However, the technique is sensitive: it is sensitive to training hyperparameters, suffers from conditional misalignment, exhibits perplexing scaling trends, and mostly underperforms vanilla Inoculation Prompting. While not a production-ready intervention, we view this as the groundwork for future interventions that enable us to guide post-training-induced misalignment via base model data curation. This post provides a high-level summary. We abstract away many details and exclude numerous experiments. We encourage readers to read our paper for more details. Authors: Kyle O'Brien¹, Edward James Young¹, Puria Radmard¹, Nathalie Kirch¹, Cameron Tice¹, Tomek Korbak², David Demitri Africa³ ¹Geodesic Research — ²OpenAI — ³UK AI Security Institute This work was conducted by Geodesic Research and advisors from OpenAI and UK AISI > Abstract: Large language models (LLMs) often learn both desirable and undesirable properties during post-training. We study whether midtraining, an earlier training stage, can shape which of these properties later generalise. We introduce Inoculation Midtraining, a technique that teaches a base model that unsafe behaviour belongs to a designated <quarantine_token> context, as indicated by the <quarantine_token> neologism (a new token) introduced during midtraining, and then post-trains the model on unsafe data within that context. We then evaluate the model outside the context, with the <quarantine_token> neologism excluded from the system prompt. Across supervised fine-tuning and reinforcement learning post-training regimes, we find that Inoculation Midtraini