学习,快速与缓慢:迈向能够持续适应的LLM
Learning, Fast and Slow: Towards LLMs That Adapt Continually
AI总结:
本文提出一种快速-缓慢学习框架,通过将模型参数作为缓慢权重和优化上下文作为快速权重,提升LLM在连续学习中的样本效率和性能,减少灾难性遗忘。
摘要:
大型语言模型(LLMs)通过更新参数(如通过强化学习)来训练下游任务,但这种更新迫使它们吸收特定任务信息,导致灾难性遗忘和失去可塑性。相比之下,固定LLM参数的上下文学习可以廉价快速适应任务需求(如提示优化),但无法自身匹配通过更新参数获得的性能提升。人类也可能以不同的时间尺度学习(如系统1与系统2)。为此,我们引入了一种快速-缓慢学习框架,将模型参数作为“缓慢”权重,优化上下文作为“快速”权重。这些快速“权重”可以从文本反馈中学习以吸收任务特定信息,同时允许缓慢权重保持接近基础模型并保留一般推理行为。快速-缓慢训练(FST)在推理任务中比仅缓慢学习(强化学习)高效3倍,同时在性能渐进上达到更高的水平。此外,FST训练的模型更接近基础LLM(KL散度减少多达70%),导致比强化学习训练更少的灾难性遗忘。这种减少的漂移也保留了可塑性:在训练一个任务后,FST训练的模型在后续任务中适应更有效,而仅参数训练的模型则不然。在连续学习场景中,当任务领域实时变化时,FST继续获取每个新任务,而仅参数强化学习则停滞。
英文摘要:
Large language models (LLMs) are trained for downstream tasks by updating their parameters (e.g., via RL). However, updating parameters forces them to absorb task-specific information, which can result in catastrophic forgetting and loss of plasticity. In contrast, in-context learning with fixed LLM parameters can cheaply and rapidly adapt to task-specific requirements (e.g., prompt optimization), but cannot by itself typically match the performance gains available through updating LLM parameters. There is no good reason for restricting learning to being in-context or in-weights. Moreover, humans also likely learn at different time scales (e.g., System 1 vs 2). To this end, we introduce a fast-slow learning framework for LLMs, with model parameters as "slow" weights and optimized context as "fast" weights. These fast "weights" can learn from textual feedback to absorb the task-specific information, while allowing slow weights to stay closer to the base model and persist general reasoning behaviors. Fast-Slow Training (FST) is up to 3x more sample-efficient than only slow learning (RL) across reasoning tasks, while consistently reaching a higher performance asymptote. Moreover, FST-trained models remain closer to the base LLM (up to 70% less KL divergence), resulting in less catastrophic forgetting than RL-training. This reduced drift also preserves plasticity: after training on one task, FST trained models adapt more effectively to a subsequent task than parameter-only trained models. In continual learning scenarios, where task domains change on the fly, FST continues to acquire each new task while parameter-only RL stalls.
机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。