Code-Switching Curriculum Learning for Multilingual Transfer in LLMs

Large language models (LLMs) now exhibit near human-level performance in various tasks, but their performance drops drastically after a handful of high-resource languages due to the imbalance in pre-training data.Inspired by the human process of second language acquisition, particularly code-switching-the practice of language alternation in a conversationwe propose code-switching curriculum learning (CSCL) to enhance cross-lingual transfer for LLMs.CSCL mimics the stages of human language learning by progressively training models with a curriculum consisting of 1) token-level code-switching, 2) sentence-level code-switching, and 3) monolingual corpora.Using Qwen 2 as our underlying model, we demonstrate the efficacy of the CSCL in improving language transfer to Korean, achieving significant performance gains compared to monolingual continual pre-training methods.Ablation studies reveal that both token-and sentence-level code-switching significantly enhance cross-lingual transfer and that curriculum learning amplifies these effects.We also extend our findings into various languages, including Japanese (high-resource) and Indonesian (lowresource), and using two additional models (Gemma 2 and Phi 3.5).We further show that CSCL mitigates spurious correlations between language resources and safety alignment, presenting a robust, efficient framework for more equitable language transfer in LLMs.We observe that CSCL is effective for low-resource settings where high-quality, monolingual corpora for language transfer are hardly available.* This work was done during an internship at NAVER AI Lab.Human 2. Sentence-Level Code-Switching 3. Monolingual Text 1. Token-Level Code-Switching 1. .2. The goal of NLP is to enable computers to understand and respond to human language.3. , , .4.Over the years, NLP algorithms and language resources have advanced.1. .2. .