What Is Reinforcement Learning (RL), How Is It Used & How Effective Is It?


By Kyle Allen
This description is based on a conversation with 'Sam', which took place over several days in January 2025

Reinforcement Learning (RL) is a machine learning approach where an AI agent learns by interacting with an environment and receiving rewards or penalties based on its actions. Unlike traditional supervised learning, which relies on labeled datasets, RL allows models to improve autonomously through trial and error. The goal is to maximize cumulative rewards over time, refining decision-making and optimizing performance. RL is commonly used in robotics, gaming, financial modeling, and autonomous systems, where real-time adaptation is critical. In AI model training, RL plays a crucial role in fine-tuning large language models (LLMs) through Reinforcement Learning from Human Feedback (RLHF). This technique helps align models like GPT-4 with human preferences by rewarding helpful, accurate, and safe responses while penalizing misleading or harmful outputs.

However, RL’s effectiveness is highly variable—while it improves AI alignment in theory, in practice, it often struggles with inconsistencies in reward signals, biases in training data, and computational inefficiencies. RL is implemented by human beings: AI research teams, machine learning engineers, and expert annotators who design reward mechanisms, test edge cases, and fine-tune models based on performance feedback. However, these human-in-the-loop interventions can introduce their own biases, limiting RL’s ability to generalize across diverse real-world scenarios. Models can become over-optimized for specific prompts rather than truly understanding concepts, leading to rigid or misleading outputs. Despite its potential, RL remains an imperfect tool, requiring continuous refinement to produce reliable AI behavior.