Momentum at SemEval-2026 Task 2: LongVA-RoBERTa, a transformer-Based Longitudinal Valence and Arousal Modeling
Paper · 2026 · Supriya Nadiger, Sunil Saumya, Rahul Pujari et al.
Summary
This paper describes the Momentum team's system for SemEval-2026 Task 2. The task asks systems to estimate emotion as continuous valence and arousal scores rather than discrete categories, using longitudinal ecological essays and feeling-word responses linked to participants' self-reported EMA ratings. The team addressed two subtasks.
- Subtask 1 predicts scores for each text. LongVA-RoBERTa uses a partially fine-tuned RoBERTa-base encoder, single-head attention pooling and a two-layer MLP regressor. It also adds a few handcrafted surface features, such as text length, punctuation counts and an essay vs. feeling-word flag.
- Subtask 2A forecasts short-term changes in affect between consecutive entries. Each user's entries are put in chronological order and passed through the same encoder plus a BiLSTM and MLP.
The authors report that Subtask 1 beats the official baseline across composite, between-user and within-user evaluation, though the extracted text does not include the numbers. For Subtask 2A the system is only competitive. Its valence error is slightly lower than the baseline's, but its correlations are lower. The work shows that adding sequence modelling to transformer encoders helps with longitudinal emotion analysis.
Key points
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Data: 5,285 longitudinal entries from 182 participants, collected 2021–2024 and annotated with EMA valence and arousal ratings. The test set covers both seen and unseen users.
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Setup:
- RoBERTa-base with the lower 8 layers frozen and the top 4 fine-tuned, inputs capped at 128 tokens.
- Subtask 1: L1 loss, AdamW, learning rate 2×10⁻⁵.
- Subtask 2A: MSE loss, learning rate 1×10⁻⁴, user-grouped GroupKFold validation.
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Subtask 2A results (system vs. baseline):
Dimension System r Baseline r System MAE Baseline MAE Valence .553 .615 1.139 1.168 Arousal .589 .670 0.698 0.638 -
Ablation (Subtask 2A, Pearson r on validation):
- RoBERTa alone: 0.366 for valence, 0.312 for arousal.
- Adding user embeddings changes little.
- Adding the BiLSTM gives clear gains.
- The full model reaches 0.553 for valence and 0.589 for arousal.
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Limitation: the model treats irregular EMA time gaps as uniform steps. The authors also suggest the BiLSTM may smooth out sharp arousal spikes. Encoding elapsed time is proposed as future work.
Institutions
Fields, topics and concepts
📚 Shelves 5The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksPsychology · 1,552 worksExperimental and Cognitive Psychology · 870 worksSocial Psychology · 306 works
Cite
Cite as Supriya Nadiger, Sunil Saumya, Rahul Pujari, Veeresh Hiremath, Kiran Chikaraddi and Anoop Kadkol. 2026. Momentum at SemEval-2026 Task 2: LongVA-RoBERTa, a transformer-Based Longitudinal Valence and Arousal Modeling. Proceedings of the 20th International Workshop on Semantic Evaluation (2026).
@inproceedings{nadiger2026momentum,
title = {{Momentum at SemEval-2026 Task 2: LongVA-RoBERTa, a transformer-Based Longitudinal Valence and Arousal Modeling}},
author = {Supriya Nadiger, Sunil Saumya, Rahul Pujari, Veeresh Hiremath, Kiran Chikaraddi and Anoop Kadkol},
booktitle = {Proceedings of the 20th International Workshop on Semantic Evaluation (2026)},
year = {2026},
doi = {10.18653/v1/2026.semeval-1.78},
url = {https://doi.org/10.18653/v1/2026.semeval-1.78}
}References
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