Robust Instruction Optimization for Large Language Models with Distribution Shifts

Large Language Models have demonstrated significant ability in accomplishing a wide range of Natural Language Processing (NLP) tasks. However, their performance is highly sensitive to the even minor changes in the phrasing of the task instructions, leading to a line of research in automatic instruction optimization towards better performance for NLP tasks. Unfortunately, existing methods for instruction optimization fail to consider the distribution shift between the seen training data and the unseen test data, where testing on unseen group of data with a different distribution could potentially lead to performance drop. In this paper, we take an initial step of investigating the problem of LLM instruction optimization across data groups with distribution shifts. We find that the optimal instructions do encounter performance drops on LLM under certain distribution shifts. To this end, we propose a framework to derive more robust optimal instructions that improve the performance on the unseen data group without large sacrifice on the seen data group. Experimental results demonstrate the effectiveness of our proposed framework.