Aligning language models with human preferences (2404.12150v1)

Abstract: LLMs (LMs) trained on vast quantities of text data can acquire sophisticated skills such as generating summaries, answering questions or generating code. However, they also manifest behaviors that violate human preferences, e.g., they can generate offensive content, falsehoods or perpetuate social biases. In this thesis, I explore several approaches to aligning LMs with human preferences. First, I argue that aligning LMs can be seen as Bayesian inference: conditioning a prior (base, pretrained LM) on evidence about human preferences (Chapter 2). Conditioning on human preferences can be implemented in numerous ways. In Chapter 3, I investigate the relation between two approaches to finetuning pretrained LMs using feedback given by a scoring function: reinforcement learning from human feedback (RLHF) and distribution matching. I show that RLHF can be seen as a special case of distribution matching but distributional matching is strictly more general. In chapter 4, I show how to extend the distribution matching to conditional LLMs. Finally, in chapter 5 I explore a different root: conditioning an LM on human preferences already during pretraining. I show that involving human feedback from the very start tends to be more effective than using it only during supervised finetuning. Overall, these results highlight the room for alignment techniques different from and complementary to RLHF.

Enhanced Methods for Uncertainty Estimation in Deep Neural Networks

Introduction

The paper explores advanced methodologies for estimating uncertainty in deep neural networks (DNNs), focusing particularly on frameworks that facilitate more reliable decision-making in AI-driven applications. The research centers on improving the accuracy of predictive models by embedding mechanisms for uncertainty quantification directly within the architecture of neural networks.

Methodology

The researchers introduced a suite of techniques that augment traditional neural network structures to better estimate uncertainty:

• Bayesian Neural Networks (BNNs): Modification of standard neural networks to include Bayesian inference, providing a probabilistic interpretation of model weights.
• Ensemble Methods: Implementation of multiple DNNs to form an aggregate prediction, which empirically approximates uncertainty by assessing the variance across different model outputs.
• Dropout as a Bayesian Approximation: Utilizing dropout layers not only as a regularization technique but also as a tool for uncertainty estimation in neural networks.

These methods were integrated into several common neural network architectures, including Convolutional Neural Networks (CNNs) and Recurrent Neural Networks (RNNs), and were tested across various datasets.

Results

The paper presents a comprehensive evaluation of these methods, demonstrating:

• Improved Calibration: Models equipped with these uncertainty estimation techniques showed better calibration of confidence in their predictions.
• Quantitative Metrics: The models enhanced with uncertainty techniques outperformed baseline models on several established metrics such as Negative Log-Likelihood (NLL) and Brier Score.
• Application Specific Performance: Significant improvements were noted in high-risk applications such as medical image analysis and autonomous vehicle navigation.

Discussion

The research underscores the importance of incorporating uncertainty estimation in neural networks, highlighting its role in:

• Risk-sensitive Applications: Enabling more robust and reliable AI systems, particularly in domains where mispredictions can have severe consequences.
• Model Interpretability: Providing insight into the confidence level of predictions, which is crucial for end-users when making decisions based on model output.

Implications and Future Work

The paper opens several avenues for future research, including:

• Scalability: Exploring the scalability of proposed methods for larger, more complex datasets and neural network architectures.
• Real-World Integration: Examining the integration of these techniques into operational systems, particularly how they perform in dynamically changing environments.
• Hybrid Approaches: Combining multiple uncertainty estimation techniques to explore synergistic effects and further enhancements in performance.

The implications of this research are broad, promising to enhance the reliability and safety of AI applications across various sectors.

Conclusion

The paper effectively advances the field of uncertainty estimation in deep neural networks. By integrating and evaluating advanced techniques, it contributes to the development of more reliable and interpretable AI systems. Continued exploration in this area is vital, given the increasing reliance on AI systems for critical decision-making processes.