João A. Leite
Author directory2026
LLM-Based Adversarial Persuasion Attacks on Fact-Checking Systems
João A. Leite | Olesya Razuvayevskaya | Kalina Bontcheva | Carolina Scarton
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
João A. Leite | Olesya Razuvayevskaya | Kalina Bontcheva | Carolina Scarton
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Automated fact-checking (AFC) systems are susceptible to adversarial attacks, enabling false claims to evade detection. Existing adversarial frameworks typically rely on injecting noise or altering semantics, yet no existing framework exploits the adversarial potential of persuasion techniques against AFC systems, which are widely used in disinformation campaigns to manipulate audiences. In this paper, we introduce a novel class of persuasive adversarial attacks on AFCs by employing an LLM to rephrase claims using persuasion techniques. Considering 15 techniques grouped into 5 categories, we study the effects of persuasion on both claim verification and evidence retrieval using a decoupled evaluation strategy. Experiments on the FEVER and FEVEROUS benchmarks show that persuasion attacks can substantially degrade both verification performance and evidence retrieval. Our analysis identifies persuasion techniques as a potent class of adversarial attacks, highlighting the need for more robust AFC systems.
2023
SheffieldVeraAI at SemEval-2023 Task 3: Mono and Multilingual Approaches for News Genre, Topic and Persuasion Technique Classification
Ben Wu | Olesya Razuvayevskaya | Freddy Heppell | João A. Leite | Carolina Scarton | Kalina Bontcheva | Xingyi Song
Proceedings of the 17th International Workshop on Semantic Evaluation (SemEval-2023)
Ben Wu | Olesya Razuvayevskaya | Freddy Heppell | João A. Leite | Carolina Scarton | Kalina Bontcheva | Xingyi Song
Proceedings of the 17th International Workshop on Semantic Evaluation (SemEval-2023)
This paper describes our approach for SemEval- 2023 Task 3: Detecting the category, the fram- ing, and the persuasion techniques in online news in a multilingual setup. For Subtask 1 (News Genre), we propose an ensemble of fully trained and adapter mBERT models which was ranked joint-first for German, and had the high- est mean rank of multi-language teams. For Subtask 2 (Framing), we achieved first place in 3 languages, and the best average rank across all the languages, by using two separate ensem- bles: a monolingual RoBERTa-MUPPETLARGE and an ensemble of XLM-RoBERTaLARGE with adapters and task adaptive pretraining. For Sub- task 3 (Persuasion Techniques), we trained a monolingual RoBERTa-Base model for English and a multilingual mBERT model for the re- maining languages, which achieved top 10 for all languages, including 2nd for English. For each subtask, we compared monolingual and multilingual approaches, and considered class imbalance techniques.