A Statistical and Multi-Perspective Revisiting of the Membership Inference Attack in Large Language Models

Fuente: arXiv
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Main Authors: Chen, Bowen, Han, Namgi, Miyao, Yusuke
Format: Preprint
Published: 2024
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author Chen, Bowen
Han, Namgi
Miyao, Yusuke
author_facet Chen, Bowen
Han, Namgi
Miyao, Yusuke
contents The lack of data transparency in Large Language Models (LLMs) has highlighted the importance of Membership Inference Attack (MIA), which differentiates trained (member) and untrained (non-member) data. Though it shows success in previous studies, recent research reported a near-random performance in different settings, highlighting a significant performance inconsistency. We assume that a single setting doesn't represent the distribution of the vast corpora, causing members and non-members with different distributions to be sampled and causing inconsistency. In this study, instead of a single setting, we statistically revisit MIA methods from various settings with thousands of experiments for each MIA method, along with study in text feature, embedding, threshold decision, and decoding dynamics of members and non-members. We found that (1) MIA performance improves with model size and varies with domains, while most methods do not statistically outperform baselines, (2) Though MIA performance is generally low, a notable amount of differentiable member and non-member outliers exists and vary across MIA methods, (3) Deciding a threshold to separate members and non-members is an overlooked challenge, (4) Text dissimilarity and long text benefit MIA performance, (5) Differentiable or not is reflected in the LLM embedding, (6) Member and non-members show different decoding dynamics.
format Preprint
id arxiv_https___arxiv_org_abs_2412_13475
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A Statistical and Multi-Perspective Revisiting of the Membership Inference Attack in Large Language Models
Chen, Bowen
Han, Namgi
Miyao, Yusuke
Computation and Language
Artificial Intelligence
The lack of data transparency in Large Language Models (LLMs) has highlighted the importance of Membership Inference Attack (MIA), which differentiates trained (member) and untrained (non-member) data. Though it shows success in previous studies, recent research reported a near-random performance in different settings, highlighting a significant performance inconsistency. We assume that a single setting doesn't represent the distribution of the vast corpora, causing members and non-members with different distributions to be sampled and causing inconsistency. In this study, instead of a single setting, we statistically revisit MIA methods from various settings with thousands of experiments for each MIA method, along with study in text feature, embedding, threshold decision, and decoding dynamics of members and non-members. We found that (1) MIA performance improves with model size and varies with domains, while most methods do not statistically outperform baselines, (2) Though MIA performance is generally low, a notable amount of differentiable member and non-member outliers exists and vary across MIA methods, (3) Deciding a threshold to separate members and non-members is an overlooked challenge, (4) Text dissimilarity and long text benefit MIA performance, (5) Differentiable or not is reflected in the LLM embedding, (6) Member and non-members show different decoding dynamics.
title A Statistical and Multi-Perspective Revisiting of the Membership Inference Attack in Large Language Models
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2412.13475