Explanation: Supervised Fine-Tuning & Reinforcement Learning from Human Feedback

Joonbeom Kwon
4 min readNov 27, 2023

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In the intricate and multifaceted world of artificial intelligence (AI), understanding the nuances of training methodologies is pivotal for anyone looking to dive deeper into this field. Two of the most prominent training approaches that have garnered significant attention are Supervised Fine-Tuning (SFT) and Reinforcement Learning from Human Feedback (RLHF). Each of these methods offers a unique perspective on how AI models learn, adapt, and evolve, making them suitable for various applications.

Supervised Fine-Tuning (SFT)

Imagine teaching a child how to identify different types of fruits. You show them an apple and say, “This is an apple,” then show them a banana and tell them, “This is a banana.” Supervised Fine-Tuning works in a similar way. Here, the AI model is like the child, learning from examples that are clearly labeled. For instance, in image recognition, the model is trained with thousands of images, each labeled with what it represents, like ‘cat’, ‘dog’, or ‘car’. The model learns by comparing its predictions against these labels and adjusting its parameters to reduce the difference between its guess and the actual label.

This method is particularly effective for tasks where the answers are clear-cut. For example, in email filtering, the AI is trained with thousands of emails, each labeled as ‘spam’ or ‘not spam’. The model learns to identify patterns that differentiate spam from regular emails. However, the limitation of SFT becomes evident when we consider the need for extensive and well-labeled datasets. Creating such datasets can be resource-intensive and time-consuming. Additionally, if the training data doesn’t cover a specific scenario, the model might struggle to respond correctly, highlighting a potential issue in generalizing beyond its training.

Reinforcement Learning from Human Feedback (RLHF)

Now, picture teaching a child to play chess. You don’t give them a list of right and wrong moves for every possible situation; instead, you guide them through the game, applauding good moves and discouraging bad ones. RLHF operates on a similar principle. The AI model learns by interacting with its environment and receiving feedback, not from a static dataset, but from real-world experiences and human-guided rewards or penalties.

A classic example of RLHF in action is the training of AI to play complex games like Go or chess. The AI makes moves, receives feedback on those moves, and gradually learns strategies to improve its game. Another application is in autonomous vehicles, where the AI learns from various driving scenarios. It receives positive feedback for safe maneuvers and negative feedback for risky or incorrect ones. The flexibility of RLHF makes it powerful for tasks where predefining every possible situation and correct response is impractical. However, designing an effective reward system is challenging and critical; a poorly designed system can lead the AI to develop undesirable behaviors. Additionally, the process of providing consistent, unbiased human feedback is labor-intensive and can introduce its own set of biases.

In-Depth Comparison: SFT vs RLHF

While SFT offers a structured approach to AI training, ideal for problems with clear answers and abundant data, it can be limited by the scope and quality of the training data. In contrast, RLHF, though more flexible and adaptable to complex, unpredictable scenarios, demands a careful design of the reward system and significant human involvement.

In SFT, the risk lies in the potential biases in the training data. For instance, if an image recognition model is trained primarily on pictures of animals taken during the day, it might struggle to recognize the same animals in night-time images. In RLHF, the challenge is in the reward design; for example, if an AI trained to play a game is rewarded more for defensive moves than offensive ones, it might overly focus on defense, neglecting other aspects of the game.

The choice between SFT and RLHF depends on the nature of the task. SFT is suitable for scenarios where the environment is predictable and the data is plentiful, like in handwriting recognition, where the model learns from a vast database of handwritten texts and their transcriptions. On the other hand, RLHF is more apt for dynamic, unpredictable environments, like in robotic navigation, where the robot must learn to navigate through different terrains and obstacles, a scenario where pre-labeled data is insufficient.

Conclusion

Grasping the intricacies of Supervised Fine-Tuning and Reinforcement Learning from Human Feedback is crucial for anyone delving into the field of AI. These methodologies, each with their strengths and limitations, cater to different aspects of AI learning and problem-solving. In practice, the choice of method often depends on the specific demands and complexities of the task at hand. Sometimes, a hybrid approach that combines elements of both SFT and RLHF might provide the most effective solution. Whether you’re a budding AI enthusiast or a seasoned professional, a thorough understanding of these approaches is key to navigating the complex landscape of AI training and development.

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