QuadCore at ArGuard Shared Tasks: A Simple Threshold Calibration Approach for Arabic Hateful Meme Detection

Umme Saima Tonny, Maimuna Tabassum, Sidratul Muntaha, Sabila Anzum


Abstract
We describe our system for Subtask A1 (binary hateful meme detection) of the ArGuard 2026 shared task (Alam et al., 2026). Our final system fine-tunes MARBERTv2 with class-weighted loss and macro-F1-based checkpoint selection, then applies a post-hoc decision-threshold calibration to correct for a class-distribution shift we found between the training/development splits (37.8% Hateful) and the held-out test split (29.6% Hateful). This calibration step requires no retraining and adds 3.3 macro-F1 points (0.7286 → 0.7616) on the official test split. On the same test split, this calibrated system also outperforms two alternatives we evaluated there – multi-seed ensembling and naive multimodal late-fusion. They match or exceed backbone-substitution and multi-model-ensemble variants that we were only able to evaluate on local development data. We report our full experimental log, including the negative results, with each result explicitly labeled by evaluation split, and compare our score to the AHA-Memes benchmark, where a much larger vision-language model reaches a similar range. Code and configuration files are released for reproducibility.
Anthology ID:
2026.arabicnlp-sharedtasks.64
Volume:
Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Muhammad Abdul-Mageed, Tamer Elsayed, Houda Bouamor, Samhaa El-Beltagy, Hend Al-Khalifa, Ahmed Abdelali, AbdelRahim Elmadany, Abdellah El Mekki, Kareem Darwish, Sakhar Alkhereyf, Hamzah Luqman, Salam Khalifa, Samar Magdy, Zaid Alyafeai, Injy Hamed, Wajdi Zaghouani, Imed Zitouni
Venue:
ArabicNLP
SIG:
SIGARAB
Publisher:
Association for Computational Linguistics
Note:
Pages:
490–496
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.64/
DOI:
Bibkey:
Cite (ACL):
Umme Saima Tonny, Maimuna Tabassum, Sidratul Muntaha, and Sabila Anzum. 2026. QuadCore at ArGuard Shared Tasks: A Simple Threshold Calibration Approach for Arabic Hateful Meme Detection. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 490–496, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
QuadCore at ArGuard Shared Tasks: A Simple Threshold Calibration Approach for Arabic Hateful Meme Detection (Tonny et al., ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.64.pdf