In-Context Learning Demonstration Selection via Influence Analysis
Vinay M. S., Minh-Hao Van, Xintao Wu
TL;DR
This work tackles the problem of selecting demonstrations for in-context learning in large language models by introducing InfICL, an influence-analysis-based method that identifies the most impactful training samples using embeddings from a local LLM and trains a lightweight classifier to estimate per-sample influence. Demonstrations are constructed by selecting the top-R influential samples per class, enabling balanced, high-quality prompts without fine-tuning the external LLM. A running-cost analysis shows InfICL requires mainly local-LLM embeddings and a single external inference per test, offering significant cost advantages over retraining-based influence methods. Empirical evaluations on CoLA, RTE, and SST2 with multiple external LLMs demonstrate that InfICL often achieves superior ICL performance while reducing costly API calls, though some dataset-model combinations may favor alternative strategies; the work also analyzes influence-score ranges and statistical significance to support the approach.
Abstract
Large Language Models (LLMs) have showcased their In-Context Learning (ICL) capabilities, enabling few-shot learning without the need for gradient updates. Despite its advantages, the effectiveness of ICL heavily depends on the choice of demonstrations. Selecting the most effective demonstrations for ICL remains a significant research challenge. To tackle this issue, we propose a demonstration selection method named InfICL, which utilizes influence functions to analyze impacts of training samples. By identifying the most influential training samples as demonstrations, InfICL aims to enhance the ICL generalization performance. To keep InfICL cost-effective, we only use the LLM to generate sample input embeddings, avoiding expensive fine-tuning. Through empirical studies on various real-world datasets, we demonstrate advantages of InfICL compared to state-of-the-art baselines.
