CLaC at SemEval-2026 Task 6: Response Clarity Detection in Political Discourse
Paper · 2026 · Nawar Turk, Lucas Miquet-Westphal and Leila Kosseim
Summary
The CLaC team built a system for SemEval-2026 Task 6 (CLARITY), which asks how clearly U.S. presidents answer interview questions. Task 1 sorts answers into 3 Clarity classes. Task 2 assigns 9 finer Evasion labels. The data are 3,993 English question-answer pairs, and the labels are strongly imbalanced.
The authors compared three families of approaches:
- eight transformer encoders, each tuned through a four-stage pipeline;
- a Longformer variant for inputs longer than 512 tokens;
- prompted LLMs, tested under several prompting strategies.
The strongest setup was a majority-vote ensemble of GPT-5, Gemini-3-Flash-Preview and Qwen3-235B-Instruct. It used 27 class-balanced examples, the interviewer's full turn as context, and label definitions extended with their Evasion subcategories. Because time ran out, this Task 1 setup was reused unchanged for Task 2.
The ensemble scored 80 macro-F1 on Task 1 (9th of 41) and 59 on Task 2 (3rd of 33). Prompting without any fine-tuning beat the tuned encoders, especially on minority classes. The work suggests that for small, hierarchically labelled tasks, prompt and ensemble design can matter more than updating model weights.
Key points
- Dataset: 3,448 train, 308 dev and 237 test pairs. The dev set carries three independent Evasion annotations per instance.
- Encoder tuning: Unfreezing only the top 25% of layers averaged 59.1 dev macro-F1, versus 41.2 for full fine-tuning. DeBERTa-v3-base was the best single encoder (65.1).
- Dev-set comparison: Mixing English and multilingual encoders gave 70.5, Longformer-base-4096 reached 64.3, and the LLM ensemble reached 78.1. Extra interviewer context helped the LLMs but slightly hurt the encoders.
- Prompt refinement: Adding Level-2 subcategory descriptions to the label definitions raised GPT-5 from 64.4 to 71.5. Among open-weight LLMs, model size did not predict accuracy.
- Main error source: Both ensembles most often confused Clear Reply with Ambivalent, the same boundary where human annotators agree least (κ = 0.65). Code and prompts are released on GitHub (CLaC-Lab).
Institutions
Fields, topics and concepts
📚 Shelves 4The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksArts and Humanities · 16,039 worksLanguage and Linguistics · 15,891 works
Cite
Cite as Nawar Turk, Lucas Miquet-Westphal and Leila Kosseim. 2026. CLaC at SemEval-2026 Task 6: Response Clarity Detection in Political Discourse. Proceedings of the 20th International Workshop on Semantic Evaluation (2026).
@inproceedings{turk2026clac,
title = {{CLaC at SemEval-2026 Task 6: Response Clarity Detection in Political Discourse}},
author = {Nawar Turk, Lucas Miquet-Westphal and Leila Kosseim},
booktitle = {Proceedings of the 20th International Workshop on Semantic Evaluation (2026)},
year = {2026},
doi = {10.18653/v1/2026.semeval-1.238},
url = {https://doi.org/10.18653/v1/2026.semeval-1.238}
}References
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