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Exploring Over-Memorization: A Unified Perspective on Overfitting in Deep Neural Networks


Core Concepts
Deep neural networks exhibit a shared behaviour termed over-memorization, where they suddenly become high-confidence in predicting certain training patterns and retain a persistent memory for them, leading to a decline in generalization ability across various training paradigms.
Abstract
The paper examines the memorization effect in deep neural networks (DNNs) and reveals a shared behaviour termed over-memorization, which impairs their generalization capacity. This behaviour manifests as DNNs suddenly becoming high-confidence in predicting certain training patterns and retaining a persistent memory for them. The authors observe that when DNNs over-memorize an adversarial pattern, they tend to simultaneously exhibit high-confidence prediction for the corresponding natural pattern. These findings motivate the authors to propose a general framework, Distraction Over-Memorization (DOM), which explicitly prevents over-memorization by either removing or augmenting the high-confidence natural patterns. Extensive experiments demonstrate the effectiveness of the proposed DOM framework in mitigating overfitting across various training paradigms, including natural training, multi-step adversarial training, and single-step adversarial training. The authors show that DOM can consistently outperform baseline methods in reducing the generalization gap and improving model robustness.
Stats
"Shortly after the first learning rate decay (150th epoch), the model occurs natural overfitting, resulting in a 5% performance gap between training and test patterns." "Aligned with the onset of natural overfitting, the proportion of the model's high-confidence (loss range 0-0.2) prediction patterns suddenly increases by 20%." "Removing the transformed high-confidence patterns can effectively alleviate natural overfitting, whereas removing the original high-confidence patterns negatively affects the model's generalization." "With the onset of robust overfitting and catastrophic overfitting, the model abruptly becomes high-confidence in predicting certain adversarial patterns." "The AT-trained model exhibits a similar memory tendency in over-memorization samples: when it over-memorizes certain adversarial patterns, it will simultaneously display high-confidence predictions for the corresponding natural patterns."
Quotes
"DNNs tend to exhibit sudden high-confidence predictions and maintain persistent memory for certain training patterns, which results in a decrease in generalization ability." "When the model over-memorizes an adversarial pattern, it tends to simultaneously exhibit high-confidence in predicting the corresponding natural pattern."

Deeper Inquiries

How can the proposed over-memorization framework be extended to other machine learning tasks beyond image classification, such as natural language processing or speech recognition

The proposed over-memorization framework can be extended to other machine learning tasks beyond image classification by adapting the concept of preventing over-memorization in training patterns to suit the specific characteristics of tasks like natural language processing (NLP) or speech recognition. In NLP, for example, the framework could focus on preventing models from over-memorizing specific phrases or linguistic patterns that may lead to decreased generalization. This could involve identifying high-confidence predictions on certain text sequences and applying strategies to mitigate the over-memorization effect, such as removing or augmenting those patterns during training. Similarly, in speech recognition tasks, the framework could target preventing the model from over-memorizing specific audio features or phonetic patterns that could hinder generalization. By adapting the framework to these tasks, it can help improve the robustness and generalization of models in various machine learning domains beyond image classification.

What are the potential theoretical explanations for the shared over-memorization behaviour observed across different training paradigms

The shared over-memorization behavior observed across different training paradigms can potentially be theoretically explained by the concept of the model prioritizing learning specific patterns over generalizing to unseen data. One theoretical explanation could be related to the optimization landscape of deep neural networks, where the model tends to converge to solutions that prioritize memorizing certain training patterns rather than learning robust and generalizable representations. This behavior may stem from the model's capacity to easily memorize specific patterns due to the high dimensionality of the feature space, leading to overfitting and decreased generalization. Additionally, the shared over-memorization behavior could be attributed to the model's tendency to rely on high-confidence predictions for certain patterns, reinforcing these patterns in memory and hindering the model's ability to generalize effectively. By understanding the underlying optimization dynamics and the model's learning behavior, researchers can further explore theoretical explanations for the observed over-memorization phenomenon across different training paradigms.

Can the insights from this study be leveraged to develop more efficient and robust training algorithms for deep neural networks in the future

The insights from this study can be leveraged to develop more efficient and robust training algorithms for deep neural networks in the future by incorporating strategies to prevent over-memorization and enhance generalization. By focusing on mitigating overfitting through the Distraction Over-Memorization (DOM) framework, researchers can design training algorithms that prioritize learning diverse and representative features while avoiding the memorization of specific training patterns. This can lead to improved model robustness, better generalization to unseen data, and enhanced performance across various tasks and datasets. Additionally, the insights from this study can inform the development of novel regularization techniques, data augmentation strategies, and optimization algorithms that specifically target preventing over-memorization and promoting more effective learning in deep neural networks. By integrating these insights into training algorithms, researchers can advance the field of deep learning and create models that are more resilient, efficient, and capable of handling diverse real-world challenges.
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