论文标题

重新思考任务抽样,以进行几次视觉语言转移学习

Rethinking Task Sampling for Few-shot Vision-Language Transfer Learning

论文作者

Wang, Zhenhailong, Yu, Hang, Li, Manling, Zhao, Han, Ji, Heng

论文摘要

尽管达到了最新的零射击性能,但现有的视觉语言模型仍然缺乏针对域特异性问题的少量转移能力。经典的微调通常无法防止高度表达模型利用虚假相关性。尽管模型不合时宜的元学习(MAML)作为几次转移学习的天然替代方案,但由于隐式二阶优化而引起的昂贵计算限制了其在大规模视觉语言模型(例如剪辑)上的使用。尽管许多文献都致力于探索替代优化策略,但我们确定了有效的几次转移学习,任务抽样的另一个基本方面,以前仅将其视为MAML中数据预处理的一部分。为了显示任务采样的影响,我们提出了一种简单的算法,模型不合时式多任务微调(MAMF),该算法仅在均匀地采样多个任务上区分了经典的微调。尽管它很简单,但我们表明,MAMF在五个少数几张视觉语言分类任务上始终超过经典的微调。我们进一步表明,在少数射击视觉分类的上下文中,MAML中双层优化的有效性对任务的零弹性性能高度敏感。本文的目的是提供有关几乎没有成功学习工作的新见解,并鼓励更多的研究来调查更好的任务抽样策略。

Despite achieving state-of-the-art zero-shot performance, existing vision-language models still fall short of few-shot transfer ability on domain-specific problems. Classical fine-tuning often fails to prevent highly expressive models from exploiting spurious correlations. Although model-agnostic meta-learning (MAML) presents as a natural alternative for few-shot transfer learning, the expensive computation due to implicit second-order optimization limits its use on large-scale vision-language models such as CLIP. While much literature has been devoted to exploring alternative optimization strategies, we identify another essential aspect towards effective few-shot transfer learning, task sampling, which is previously only be viewed as part of data pre-processing in MAML. To show the impact of task sampling, we propose a simple algorithm, Model-Agnostic Multitask Fine-tuning (MAMF), which differentiates classical fine-tuning only on uniformly sampling multiple tasks. Despite its simplicity, we show that MAMF consistently outperforms classical fine-tuning on five few-shot vision-language classification tasks. We further show that the effectiveness of the bi-level optimization in MAML is highly sensitive to the zero-shot performance of a task in the context of few-shot vision-language classification. The goal of this paper is to provide new insights on what makes few-shot learning work, and encourage more research into investigating better task sampling strategies.

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