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When Agents Persuade: Propaganda Generation and Mitigation in LLMs

Julia Jose, Ritik Roongta, Rachel Greenstadt

TL;DR

It is found that fine-tuning LLM-based agents with propaganda objectives significantly reduces their tendency to generate such content, with ORPO (Odds Ratio Preference Optimization) proving most effective.

Abstract

Despite their wide-ranging benefits, LLM-based agents deployed in open environments can be exploited to produce manipulative material. In this study, we task LLMs with propaganda objectives and analyze their outputs using two domain-specific models: one that classifies text as propaganda or non-propaganda, and another that detects rhetorical techniques of propaganda (e.g., loaded language, appeals to fear, flag-waving, name-calling). Our findings show that, when prompted, LLMs exhibit propagandistic behaviors and use a variety of rhetorical techniques in doing so. We also explore mitigation via Supervised Fine-Tuning (SFT), Direct Preference Optimization (DPO), and ORPO (Odds Ratio Preference Optimization). We find that fine-tuning significantly reduces their tendency to generate such content, with ORPO proving most effective.

When Agents Persuade: Propaganda Generation and Mitigation in LLMs

TL;DR

It is found that fine-tuning LLM-based agents with propaganda objectives significantly reduces their tendency to generate such content, with ORPO (Odds Ratio Preference Optimization) proving most effective.

Abstract

Despite their wide-ranging benefits, LLM-based agents deployed in open environments can be exploited to produce manipulative material. In this study, we task LLMs with propaganda objectives and analyze their outputs using two domain-specific models: one that classifies text as propaganda or non-propaganda, and another that detects rhetorical techniques of propaganda (e.g., loaded language, appeals to fear, flag-waving, name-calling). Our findings show that, when prompted, LLMs exhibit propagandistic behaviors and use a variety of rhetorical techniques in doing so. We also explore mitigation via Supervised Fine-Tuning (SFT), Direct Preference Optimization (DPO), and ORPO (Odds Ratio Preference Optimization). We find that fine-tuning significantly reduces their tendency to generate such content, with ORPO proving most effective.
Paper Structure (34 sections, 2 figures, 13 tables)

This paper contains 34 sections, 2 figures, 13 tables.

Figures (2)

  • Figure 1: Clustered heatmap showing the average number of occurrences of six rhetorical techniques across human-written and LLM-generated articles. Columns represent each dataset (propaganda vs. non-propaganda for humans, GPT-4o, Llama-3.1, and Mistral Small 3), and darker shades indicate more frequent use of a technique.
  • Figure 2: (Left) Frequency of techniques across fine-tuning methods. (Right) Rhetorical techniques across fine-tuned and unfine-tuned versions.