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Main Authors: Wachowiak, Lennart, Blain, Scott D., Williams-King, David, Marro, Samuele
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2605.08321
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author Wachowiak, Lennart
Blain, Scott D.
Williams-King, David
Marro, Samuele
author_facet Wachowiak, Lennart
Blain, Scott D.
Williams-King, David
Marro, Samuele
contents LLMs are increasingly capable of persuasion, which raises the question of how to protect users against manipulation. In a preregistered user study (N=120) across four decision-making scenarios, we find that an adversarial LLM with a hidden goal succeeds in steering users' decisions 65.4% of the time. We then introduce a "warden" model: a secondary LLM that monitors the human-AI interaction trace in real time and issues non-binding, private advisories to the user when it detects manipulation. Adding a warden more than halves the adversary's success rate to 30.4%, with a much smaller (8.6 percentage points) reduction for genuine interactions. To probe the mechanism behind these results, we release COAX-Bench, a simulation benchmark spanning 14 decision-making scenarios, including hiring, voting, and file access. Across 16,212 simulated multi-agent interactions, capable adversarial LLMs achieve their hidden goals in 34.7% of cases, which warden models reduce to 12.3%. Notably, even warden models substantially weaker than the adversary they oversee provide meaningful protection, suggesting a path for scalable oversight of more capable models.
format Preprint
id arxiv_https___arxiv_org_abs_2605_08321
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle LLM Wardens: Mitigating Adversarial Persuasion with Third-Party Conversational Oversight
Wachowiak, Lennart
Blain, Scott D.
Williams-King, David
Marro, Samuele
Machine Learning
Artificial Intelligence
Computers and Society
Human-Computer Interaction
Multiagent Systems
I.2.0; I.2.7; J.4; H.5; K.4.2
LLMs are increasingly capable of persuasion, which raises the question of how to protect users against manipulation. In a preregistered user study (N=120) across four decision-making scenarios, we find that an adversarial LLM with a hidden goal succeeds in steering users' decisions 65.4% of the time. We then introduce a "warden" model: a secondary LLM that monitors the human-AI interaction trace in real time and issues non-binding, private advisories to the user when it detects manipulation. Adding a warden more than halves the adversary's success rate to 30.4%, with a much smaller (8.6 percentage points) reduction for genuine interactions. To probe the mechanism behind these results, we release COAX-Bench, a simulation benchmark spanning 14 decision-making scenarios, including hiring, voting, and file access. Across 16,212 simulated multi-agent interactions, capable adversarial LLMs achieve their hidden goals in 34.7% of cases, which warden models reduce to 12.3%. Notably, even warden models substantially weaker than the adversary they oversee provide meaningful protection, suggesting a path for scalable oversight of more capable models.
title LLM Wardens: Mitigating Adversarial Persuasion with Third-Party Conversational Oversight
topic Machine Learning
Artificial Intelligence
Computers and Society
Human-Computer Interaction
Multiagent Systems
I.2.0; I.2.7; J.4; H.5; K.4.2
url https://arxiv.org/abs/2605.08321