Prompt-Based Bias Calibration for Better Zero/Few-Shot Learning of Language Models

Kang He, Yinghan Long, Kaushik Roy


Abstract
Prompt-based learning is susceptible to intrinsic bias present in pre-trained language models (LMs), leading to sub-optimal performance in prompt-based zero/few-shot settings. In this work, we propose a null-input prompting method to calibrate intrinsic bias encoded in pre-trained LMs. Different from prior efforts that address intrinsic bias primarily for social fairness and often involve excessive computational cost, our objective is to explore enhancing LMs’ performance in downstream zero/few-shot learning while emphasizing the efficiency of intrinsic bias calibration. Specifically, we leverage a diverse set of auto-selected null-meaning inputs generated from GPT-4 to probe intrinsic bias of pre-trained LMs. Utilizing the bias-reflected probability distribution, we formulate a distribution disparity loss for bias calibration, where we exclusively update bias parameters (0.1% of total parameters) of LMs towards equal probability distribution. Experimental results show that the calibration promotes an equitable starting point for LMs while preserving language modeling abilities. Across a wide range of datasets, including sentiment analysis and topic classification, our method significantly improves zero/few-shot learning performance of LMs for both in-context learning and prompt-based fine-tuning (on average 9% and 2%, respectively).
Anthology ID:
2024.findings-emnlp.741
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2024
Month:
November
Year:
2024
Address:
Miami, Florida, USA
Editors:
Yaser Al-Onaizan, Mohit Bansal, Yun-Nung Chen
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
12673–12691
Language:
URL:
https://aclanthology.org/2024.findings-emnlp.741
DOI:
Bibkey:
Cite (ACL):
Kang He, Yinghan Long, and Kaushik Roy. 2024. Prompt-Based Bias Calibration for Better Zero/Few-Shot Learning of Language Models. In Findings of the Association for Computational Linguistics: EMNLP 2024, pages 12673–12691, Miami, Florida, USA. Association for Computational Linguistics.
Cite (Informal):
Prompt-Based Bias Calibration for Better Zero/Few-Shot Learning of Language Models (He et al., Findings 2024)
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PDF:
https://aclanthology.org/2024.findings-emnlp.741.pdf