In-context learning (ICL) has become the default method for using large
language models (LLMs), making the exploration of its limitations and
understanding the underlying causes crucial. In this paper, we find that ICL
falls short of handling specification-heavy tasks, which are tasks with
complicated and extensive task specifications, requiring several hours for
ordinary humans to master, such as traditional information extraction tasks.
The performance of ICL on these tasks mostly cannot reach half of the
state-of-the-art results. To explore the reasons behind this failure, we
conduct comprehensive experiments on 18 specification-heavy tasks with various
LLMs and identify three primary reasons: inability to specifically understand
context, misalignment in task schema comprehension with humans, and inadequate
long-text understanding ability. Furthermore, we demonstrate that through
fine-tuning, LLMs can achieve decent performance on these tasks, indicating
that the failure of ICL is not an inherent flaw of LLMs, but rather a drawback
of existing alignment methods that renders LLMs incapable of handling
complicated specification-heavy tasks via ICL. To substantiate this, we perform
dedicated instruction tuning on LLMs for these tasks and observe a notable
improvement. We hope the analyses in this paper could facilitate advancements
in alignment methods enabling LLMs to meet more sophisticated human demands.

通过对 18 个字段密集型任务进行全面实验，我们发现，针对这些任务，大规模语言模型在使用上下文学习的方法上存在三个主要问题：无法准确理解上下文、与人类任务模式理解不匹配、对长文本理解能力不足。然而，通过微调，大规模语言模型能够在这些任务上取得不错的表现，表明上下文学习的失败并非大规模语言模型本身的固有缺陷，而是现有对齐方法的局限性导致大规模语言模型无法通过上下文学习来处理这些复杂任务。我们希望本文的分析结果能促进对齐方法的发展，使大规模语言模型能够满足更加复杂的人类需求。