LexMachina at SemEval-2026 Task 2: Predicting Variation in Emotional Valence and Arousal over Time from Ecological Essays

Somdev Ganguli, Vibhan Dutta, Romit Datta, Amit Barman, Sudip Naskar


Abstract
Tracking emotional dynamics like valence and arousal is critical for understanding users’ affective baselines in ecological text. However, encoder models often struggle to distinguish stable user traits from dynamic shifts, leading to poor generalization. This paper presents LexMachina, our system for SemEval-2026 Task 2, addressing "domain shift" and "regression to the mean." LexMachina utilizes a DeBERTa-v3-Base backbone with a bifurcated strategy: post-hoc Isotonic Regression for valence calibration and a Domain Adversarial Neural Network (DANN) to mitigate user-bias in arousal. LexMachina achieved composite scores of r=0.645 (Valence) and r=0.434 (Arousal), demonstrating that adversarial disentanglement effectively captures nuances in longitudinal affective data.
Anthology ID:
2026.semeval-1.79
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:
553–560
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URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.79/
DOI:
Bibkey:
Cite (ACL):
Somdev Ganguli, Vibhan Dutta, Romit Datta, Amit Barman, and Sudip Naskar. 2026. LexMachina at SemEval-2026 Task 2: Predicting Variation in Emotional Valence and Arousal over Time from Ecological Essays. In Proceedings of the 20th International Workshop on Semantic Evaluation (2026), pages 553–560, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
LexMachina at SemEval-2026 Task 2: Predicting Variation in Emotional Valence and Arousal over Time from Ecological Essays (Ganguli et al., SemEval 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl-workshops/2026.semeval-1.79.pdf
Supplementarymaterial:
 2026.semeval-1.79.SupplementaryMaterial.zip