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Token自适应Loss重加权 (TALR)
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大模型微调范式认知再被颠覆?UIUC、Amazon团队最新研究指出SFT灾难性遗忘问题或被误解
机器之心· 2025-10-21 03:43
Core Insights - The article discusses the impact of supervised fine-tuning (SFT) on the general capabilities of large language models (LLMs), suggesting that SFT does not always lead to a significant decline in general performance when a smaller learning rate is used [2][34] - The research challenges the long-held belief that domain-specific fine-tuning inevitably causes catastrophic forgetting of general capabilities, proposing that the choice of training strategy plays a crucial role [2][34] Experiment Details - The study utilized two domain-specific datasets, MedCalc and ESCI, which represent scenarios where open-source LLMs typically perform poorly, making them ideal for domain-specific SFT [5] - Various open-source LLMs were selected for experimentation, including Qwen3-8B and Gemma3-4B, with a focus on controlling the learning rate during SFT [6] Findings - **Finding 1**: Using a smaller learning rate (e.g., 1e-6) allows models to maintain strong performance in target domains while significantly reducing the decline in general capabilities [11] - **Finding 2**: For classification tasks, when the training objective includes only the final label, a wider range of learning rates can achieve ideal performance, as seen in the ESCI dataset [12][14] Theoretical Analysis - The research team concluded that smaller learning rates can effectively limit the decline in general performance, aligning with the experimental findings [17] - The analysis also indicated that when training targets only include final labels, the number of "hard tokens" encountered decreases, allowing for a broader acceptable learning rate range [17] Token Adaptive Loss Reweighting (TALR) - TALR is introduced as a method to dynamically adjust the loss weights of tokens based on their prediction probabilities, effectively reducing the impact of hard tokens during training [20] - The method allows for real-time updates of token weights, ensuring that the model's confidence levels guide the training process [21] Experimental Results - In experiments comparing various strategies to mitigate catastrophic forgetting, TALR demonstrated superior performance, especially under higher learning rates, maintaining domain gains while minimizing losses in general performance [26][27] Conclusion and Future Directions - The research emphasizes the continued importance of SFT in enhancing LLM capabilities, suggesting that while smaller learning rates and TALR are effective, further exploration of more robust strategies is necessary to address the forgetting problem [34][35] - Future research should focus on balancing domain-specific performance with general capabilities, particularly in specialized fields like medicine, where retaining foundational knowledge is crucial [35]