ShefFriday at SemEval-2026 Task 9: LLM-Based Annotation Methods for Detecting Multilingual, Multicultural and Multievent Online Polarisation

Owen Cook, Meredith Gibbons, Xingyi Song


Abstract
This paper presents our findings for SemEval-2026 Task 9. We submit to all three subtasks using an LLM-as-an-annotator strategy, simulating the data annotation process with large language models. We created 30 LLM annotators using persona injection (also known as sociodemographic prompting) and experimented with various annotation aggregation methods, including Dawid-Skene and MACE. To further increase the variability in annotator responses, we used the hatefulness detection task as proxy for identifying polarisation. Our findings indicate that this reframing of the problem is effective for the binary classification of polarisation, but is less effective for finer-grained polarisation detection. For subtasks 2 and 3, majority voting yielded the best overall performance. While our unsupervised approach does not rank as highly as supervised ones, this work provides insight into the utility of persona-based prompting and the issue of LLM annotators exhibiting high intra-model agreement.
Anthology ID:
2026.semeval-1.411
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:
3297–3309
Language:
URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.411/
DOI:
Bibkey:
Cite (ACL):
Owen Cook, Meredith Gibbons, and Xingyi Song. 2026. ShefFriday at SemEval-2026 Task 9: LLM-Based Annotation Methods for Detecting Multilingual, Multicultural and Multievent Online Polarisation. In Proceedings of the 20th International Workshop on Semantic Evaluation (2026), pages 3297–3309, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
ShefFriday at SemEval-2026 Task 9: LLM-Based Annotation Methods for Detecting Multilingual, Multicultural and Multievent Online Polarisation (Cook et al., SemEval 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.411.pdf