Exploring LLM Priming Strategies for Few-Shot Stance Classification

AbstractLarge language models (LLMs) are effective in predicting the labels of unseen target instances if instructed for the task and training instances via the prompt. LLMs generate a text with higher probability if the prompt contains text with similar characteristics, a phenomenon, called priming, that especially affects argumentation. An open question in NLP is how to systematically exploit priming to choose a set of instances suitable for a given task. For stance classification, LLMs may be primed with few-shot instances prior to identifying whether a given argument is pro or con a topic. In this paper, we explore two priming strategies for few-shot stance classification: one takes those instances that are most semantically similar, and the other chooses those that are most stance-similar. Experiments on three common stance datasets suggest that priming an LLM with stance-similar instances is particularly effective in few-shot stance classification compared to baseline strategies, and behaves largely consistently across different LLM variants.