In-Context Learning at Representation Level via Unlabeled Texts

27 Sept 2024 (modified: 05 Feb 2025)Submitted to ICLR 2025EveryoneRevisionsBibTeXCC BY 4.0
Keywords: In-context Learning, Language models, Zero-shot, Representation Learning
Abstract: Large language models (LLMs) have exhibited impressive capability of In-Context Learning (ICL), where LLMs perform relatively complicated tasks beyond the pre-training objective by conditioning on the given demonstrations. Nevertheless, ICL introduces two gaps between pre-training and inference: label appearance (presence of inserted labels in the demonstrations) and weak semantic relevance (independently sampled demonstrations exhibit less semantic coherence compared to consecutive text segments in pretraining corpora). We propose a new inference method that only use unlabeled inputs from the test set and label space. In this method, we extract the representations of the demonstrations inputs independently and fuse them to reshape the representation of the test input for inference. Inter- estingly, without access to labels, our method outperforms traditional ICL with extra information of gold labels. Furthermore, our method allows small models to outperform the zero-shot performance of models that are twice their size (e.g., GPT-Neo-2.7B surpasses Llama2-7B, and Llama2-7B outperforms Llama2-13B). Our code will be available at this.
Primary Area: foundation or frontier models, including LLMs
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Submission Number: 10425
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