Detecting Training Data of Large Language Models via Expectation Maximization

Fuente: arXiv
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Auteurs principaux: Kim, Gyuwan, Li, Yang, Spiliopoulou, Evangelia, Ma, Jie, Wang, William Yang
Format: Preprint
Publié: 2024
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_version_ 1866914278548701184
author Kim, Gyuwan
Li, Yang
Spiliopoulou, Evangelia
Ma, Jie
Wang, William Yang
author_facet Kim, Gyuwan
Li, Yang
Spiliopoulou, Evangelia
Ma, Jie
Wang, William Yang
contents Membership inference attacks (MIAs) aim to determine whether a specific example was used to train a given language model. While prior work has explored prompt-based attacks such as ReCALL, these methods rely heavily on the assumption that using known non-members as prompts reliably suppresses the model's responses to non-member queries. We propose EM-MIA, a new membership inference approach that iteratively refines prefix effectiveness and membership scores using an expectation-maximization strategy without requiring labeled non-member examples. To support controlled evaluation, we introduce OLMoMIA, a benchmark that enables analysis of MIA robustness under systematically varied distributional overlap and difficulty. Experiments on WikiMIA and OLMoMIA show that EM-MIA outperforms existing baselines, particularly in settings with clear distributional separability. We highlight scenarios where EM-MIA succeeds in practical settings with partial distributional overlap, while failure cases expose fundamental limitations of current MIA methods under near-identical conditions. We release our code and evaluation pipeline to encourage reproducible and robust MIA research.
format Preprint
id arxiv_https___arxiv_org_abs_2410_07582
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Detecting Training Data of Large Language Models via Expectation Maximization
Kim, Gyuwan
Li, Yang
Spiliopoulou, Evangelia
Ma, Jie
Wang, William Yang
Computation and Language
Artificial Intelligence
Cryptography and Security
Machine Learning
Membership inference attacks (MIAs) aim to determine whether a specific example was used to train a given language model. While prior work has explored prompt-based attacks such as ReCALL, these methods rely heavily on the assumption that using known non-members as prompts reliably suppresses the model's responses to non-member queries. We propose EM-MIA, a new membership inference approach that iteratively refines prefix effectiveness and membership scores using an expectation-maximization strategy without requiring labeled non-member examples. To support controlled evaluation, we introduce OLMoMIA, a benchmark that enables analysis of MIA robustness under systematically varied distributional overlap and difficulty. Experiments on WikiMIA and OLMoMIA show that EM-MIA outperforms existing baselines, particularly in settings with clear distributional separability. We highlight scenarios where EM-MIA succeeds in practical settings with partial distributional overlap, while failure cases expose fundamental limitations of current MIA methods under near-identical conditions. We release our code and evaluation pipeline to encourage reproducible and robust MIA research.
title Detecting Training Data of Large Language Models via Expectation Maximization
topic Computation and Language
Artificial Intelligence
Cryptography and Security
Machine Learning
url https://arxiv.org/abs/2410.07582