N-Gram Induction Heads for In-Context RL: Improving Stability and Reducing Data Needs

Abstract

In-context learning allows models like transformers to adapt to new tasks from a few examples without updating their weights, a desirable trait for reinforcement learning (RL). However, existing in-context RL methods, such as Algorithm Distillation (AD), demand large, carefully curated datasets and can be unstable and costly to train due to the transient nature of in-context learning abilities. In this work we integrated the n-gram induction heads into transformers for in-context RL. By incorporating these n-gram attention patterns, we significantly reduced the data required for generalization — up to 27 times fewer transitions in the Key-to-Door environment — and eased the training process by making models less sensitive to hyperparameters. Our approach not only matches but often surpasses the performance of AD, demonstrating the potential of n-gram induction heads to enhance the efficiency of in-context RL.