Planning is essential for solving complex tasks, yet the internal mechanisms underlying planning in neural networks remain poorly understood. Building on prior work, we analyze a recurrent neural network (RNN) trained on Sokoban, a challenging puzzle requiring sequential, irreversible decisions. We find that the RNN has a causal plan representation which predicts its future actions about 50 steps in advance. The quality and length of the represented plan increases over the first few steps. We uncover a surprising behavior: the RNN "paces" in cycles to give itself extra computation at the start of a level, and show that this behavior is incentivized by training. Leveraging these insights, we extend the trained RNN to significantly larger, out-of-distribution Sokoban puzzles, demonstrating robust representations beyond the training regime. We open-source our model and code, and believe the neural network's interesting behavior makes it an excellent model organism to deepen our understanding of learned planning.

We tested the effectiveness of "defense-in-depth" AI safety strategies, where multiple layers of filters are used to prevent AI models from generating harmful content. Our a new attack method, STACK, bypasses defenses layer-by-layer and achieved a 71% success rate on catastrophic risk scenarios where conventional attacks achieved 0% success against these multi-layered defenses.

Concept Influence attributes model behaviors to semantic directions (like linear probes or sparse autoencoder features) rather than individual test examples, improving identification of the training data that disproportionately drive unintended behaviors. Simple first-order approximations match or outperform standard influence functions while achieving over 20× computational speedups, though they degrade under significant distribution shifts.