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Main Authors: Kuwar, Bhavinkumar Vinodbhai, Maurya, Bikrant Bikram Pratap, Gupta, Priyanshu, Choudhury, Nitin
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2507.09157
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author Kuwar, Bhavinkumar Vinodbhai
Maurya, Bikrant Bikram Pratap
Gupta, Priyanshu
Choudhury, Nitin
author_facet Kuwar, Bhavinkumar Vinodbhai
Maurya, Bikrant Bikram Pratap
Gupta, Priyanshu
Choudhury, Nitin
contents Detecting deception in strategic dialogues is a complex and high-stakes task due to the subtlety of language and extreme class imbalance between deceptive and truthful communications. In this work, we revisit deception detection in the Diplomacy dataset, where less than 5% of messages are labeled deceptive. We introduce a lightweight yet effective model combining frozen BERT embeddings, interpretable linguistic and game-specific features, and a Positive-Unlabeled (PU) learning objective. Unlike traditional binary classifiers, PU-Lie is tailored for situations where only a small portion of deceptive messages are labeled, and the majority are unlabeled. Our model achieves a new best macro F1 of 0.60 while reducing trainable parameters by over 650x. Through comprehensive evaluations and ablation studies across seven models, we demonstrate the value of PU learning, linguistic interpretability, and speaker-aware representations. Notably, we emphasize that in this problem setting, accurately detecting deception is more critical than identifying truthful messages. This priority guides our choice of PU learning, which explicitly models the rare but vital deceptive class.
format Preprint
id arxiv_https___arxiv_org_abs_2507_09157
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle PU-Lie: Lightweight Deception Detection in Imbalanced Diplomatic Dialogues via Positive-Unlabeled Learning
Kuwar, Bhavinkumar Vinodbhai
Maurya, Bikrant Bikram Pratap
Gupta, Priyanshu
Choudhury, Nitin
Computation and Language
Detecting deception in strategic dialogues is a complex and high-stakes task due to the subtlety of language and extreme class imbalance between deceptive and truthful communications. In this work, we revisit deception detection in the Diplomacy dataset, where less than 5% of messages are labeled deceptive. We introduce a lightweight yet effective model combining frozen BERT embeddings, interpretable linguistic and game-specific features, and a Positive-Unlabeled (PU) learning objective. Unlike traditional binary classifiers, PU-Lie is tailored for situations where only a small portion of deceptive messages are labeled, and the majority are unlabeled. Our model achieves a new best macro F1 of 0.60 while reducing trainable parameters by over 650x. Through comprehensive evaluations and ablation studies across seven models, we demonstrate the value of PU learning, linguistic interpretability, and speaker-aware representations. Notably, we emphasize that in this problem setting, accurately detecting deception is more critical than identifying truthful messages. This priority guides our choice of PU learning, which explicitly models the rare but vital deceptive class.
title PU-Lie: Lightweight Deception Detection in Imbalanced Diplomatic Dialogues via Positive-Unlabeled Learning
topic Computation and Language
url https://arxiv.org/abs/2507.09157