CSECU-DSG at SemEval-2026 Task 10: Fine-Tuning DeBERTa Transformer Model for Conspiracy Detection

Debashish Chakraborty, Sumaiya Tabassum, Sabrina Ibnath, Abu Nowshed Chy


Abstract
Conspiracy detection aims to determine whether a social media post expresses belief in conspiracy theories. This task is essential for understanding harmful online discourse and mitigating the spread of misinformation. However, detecting conspiracy beliefs is challenging due to subtle psycholinguistic cues and the strong contextual dependency of such claims. To address these challenges, SemEval-2026 Task 10 introduced a shared task named PsyCoMark. In this paper, we describe our approach to Subtask 2, which focuses on detecting conspiracy beliefs. We propose a transformer-based classification approach using a fine-tuned DeBERTa-v3-base model to detect conspiracy beliefs in Reddit comments. Each post is processed as a single input sequence. To address class imbalance and improve generalization, we employ class-weighted cross-entropy loss with label smoothing during training. Our approach achieves competitive performance, ranked ninth among participating teams. The findings demonstrate that fine-tuned transformer models effectively capture contextual and psycholinguistic patterns in conspiracy-related discourse and achieve competitive performance compared to other systems.
Anthology ID:
2026.semeval-1.153
Volume:
Proceedings of the 20th International Workshop on Semantic Evaluation (2026)
Month:
July
Year:
2026
Address:
San Diego, California, USA
Editors:
Ekaterina Kochmar, Debanjan Ghosh, Kai North, Mamoru Komachi
Venues:
SemEval | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
1122–1127
Language:
URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.153/
DOI:
Bibkey:
Cite (ACL):
Debashish Chakraborty, Sumaiya Tabassum, Sabrina Ibnath, and Abu Nowshed Chy. 2026. CSECU-DSG at SemEval-2026 Task 10: Fine-Tuning DeBERTa Transformer Model for Conspiracy Detection. In Proceedings of the 20th International Workshop on Semantic Evaluation (2026), pages 1122–1127, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
CSECU-DSG at SemEval-2026 Task 10: Fine-Tuning DeBERTa Transformer Model for Conspiracy Detection (Chakraborty et al., SemEval 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.153.pdf
Supplementarymaterial:
 2026.semeval-1.153.SupplementaryMaterial.zip