Few-shot learning in reinforcement learning (RL) enables agents to adapt to new tasks quickly using minimal examples by building on prior knowledge. In traditional RL, an agent learns through trial and error in an environment, often requiring millions of interactions to master a task. Few-shot RL reduces this by training the agent on a set of related tasks during a meta-learning phase, allowing it to generalize to unseen tasks with just a handful of trials. For example, an agent trained to navigate various mazes could adapt to a new maze layout after only a few attempts by leveraging patterns learned from earlier environments. This approach hinges on the agent’s ability to extract reusable strategies rather than memorizing specific solutions.
Technically, few-shot RL often relies on meta-learning algorithms like Model-Agnostic Meta-Learning (MAML). During meta-training, the agent is exposed to multiple tasks, each requiring distinct but related behaviors. The algorithm optimizes the agent’s initial parameters so that small adjustments (via gradient steps) on a few examples from a new task yield good performance. For instance, a robot arm trained to manipulate different objects might learn a base policy that can quickly adapt to pick up a novel object after seeing just a few demonstrations. The agent’s policy network is designed to encode task-agnostic features, enabling rapid fine-tuning. This contrasts with standard RL, where the policy is tightly coupled to a single task’s dynamics.
Implementing few-shot RL requires careful design. First, the training tasks must be diverse enough to encourage generalization but share underlying structure. For example, training a game-playing agent on multiple levels with varying rules but similar objectives (e.g., resource collection) helps it adapt to new levels faster. Second, balancing exploration and exploitation during the few-shot phase is critical—the agent must gather enough information from limited interactions without wasting trials. Frameworks like RLlib or custom meta-RL implementations can help manage task sampling and policy updates. While promising, challenges remain, such as handling tasks that differ significantly from the training distribution or scaling to high-dimensional environments. Developers can start by experimenting with meta-RL libraries and small-scale environments to test adaptation capabilities before applying the approach to complex problems.