Take Off the Training Wheels! Progressive In-Context Learning for Effective Alignment

Zhenyu Liu, Dongfang Li, Xinshuo Hu, Xinping Zhao, Yibin Chen, Baotian Hu, Min Zhang


Abstract
Recent studies have explored the working mechanisms of In-Context Learning (ICL). However, they mainly focus on classification and simple generation tasks, limiting their broader application to more complex generation tasks in practice. To address this gap, we investigate the impact of demonstrations on token representations within the practical alignment tasks. We find that the transformer embeds the task function learned from demonstrations into the separator token representation, which plays an important role in the generation of prior response tokens. Once the prior response tokens are determined, the demonstrations become redundant. Motivated by this finding, we propose an efficient Progressive In-Context Alignment (PICA) method consisting of two stages. In the first few-shot stage, the model generates several prior response tokens via standard ICL while concurrently extracting the ICL vector that stores the task function from the separator token representation. In the following zero-shot stage, this ICL vector guides the model to generate responses without further demonstrations. Extensive experiments demonstrate that our PICA not only surpasses vanilla ICL but also achieves comparable performance to other alignment tuning methods. The proposed training-free method reduces the time cost (e.g., 5.45×) with improved alignment performance (e.g., 6.57+). Consequently, our work highlights the application of ICL for alignment and calls for a deeper understanding of ICL for complex generations. The code will be available at https://github.com/HITsz-TMG/PICA.
Anthology ID:
2024.emnlp-main.160
Volume:
Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing
Month:
November
Year:
2024
Address:
Miami, Florida, USA
Editors:
Yaser Al-Onaizan, Mohit Bansal, Yun-Nung Chen
Venue:
EMNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
2743–2757
Language:
URL:
https://aclanthology.org/2024.emnlp-main.160
DOI:
Bibkey:
Cite (ACL):
Zhenyu Liu, Dongfang Li, Xinshuo Hu, Xinping Zhao, Yibin Chen, Baotian Hu, and Min Zhang. 2024. Take Off the Training Wheels! Progressive In-Context Learning for Effective Alignment. In Proceedings of the 2024 Conference on Empirical Methods in Natural Language Processing, pages 2743–2757, Miami, Florida, USA. Association for Computational Linguistics.
Cite (Informal):
Take Off the Training Wheels! Progressive In-Context Learning for Effective Alignment (Liu et al., EMNLP 2024)
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PDF:
https://aclanthology.org/2024.emnlp-main.160.pdf