Balanced Multi-Factor In-Context Learning for Multilingual Large Language Models
Masahiro Kaneko, Alham Fikri Aji, Timothy Baldwin
TL;DR
The paper addresses the sensitivity of multilingual in-context learning (MICL) to example selection by identifying three key factors: semantic similarity, linguistic alignment, and language-specific performance. It introduces Balanced Multi-Factor ICL (BMF-ICL), which defines explicit metrics for each factor and combines them into a total score $score^{(j)} = \alpha score^{(j)}_{sem} + \beta score^{(j)}_{lag} + \gamma score^{(j)}_{per}$ with $\alpha+\beta+\gamma=1$, selecting top-k multilingual examples with weights tuned on development data. The authors validate BMF-ICL on mCSQA and TYDI across four MLLMs, reporting consistent gains over baselines and demonstrating that all three factors, as well as cross-language diversity, contribute to improved performance. The results highlight the practical value of optimizing multilingual example selection for cross-lingual knowledge transfer and suggest broader applicability to diverse generation tasks beyond question answering.
Abstract
Multilingual large language models (MLLMs) are able to leverage in-context learning (ICL) to achieve high performance by leveraging cross-lingual knowledge transfer without parameter updates. However, their effectiveness is highly sensitive to example selection, particularly in multilingual settings. Based on the findings of existing work, three key factors influence multilingual ICL: (1) semantic similarity, (2) linguistic alignment, and (3) language-specific performance. However, existing approaches address these factors independently, without explicitly disentangling their combined impact, leaving optimal example selection underexplored. To address this gap, we propose balanced multi-factor ICL (\textbf{BMF-ICL}), a method that quantifies and optimally balances these factors for improved example selection. Experiments on mCSQA and TYDI across four MLLMs demonstrate that BMF-ICL outperforms existing methods. Further analysis highlights the importance of incorporating all three factors and the importance of selecting examples from multiple languages.
