Controllable Affective Generation via Latent Vector Steering

Xixian Yong, Siyuan Chang, Yingying Zhang, Xian Wu, Xiao Zhou


Abstract
Large Language Models (LLMs) often produce emotionally flattened responses after alignment, limiting their effectiveness in affect-sensitive applications. In this paper, we propose EmoVec, a lightweight framework for controllable affective generation via latent vector steering. EmoVec extracts emotion-specific directions from paired neutral and emotion-conditioned responses using contrastive activation addition, and further purifies them through task-specific debiasing and principal subspace removal. During inference, these vectors are injected into the final residual stream with static or scenario-adaptive scaling, enabling continuous control over emotional intensity without updating model weights. Experiments across three LLMs and eight emotions show that EmoVec consistently improves emotional salience while largely preserving semantic content, fluency, and coherence. Ablation studies and human evaluation further confirm the effectiveness of vector purification and adaptive scaling, demonstrating EmoVec as a practical inference-time method for affective control in deployed LLMs.
Anthology ID:
2026.findings-emnlp.1707
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
36494–36510
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1707/
DOI:
Bibkey:
Cite (ACL):
Xixian Yong, Siyuan Chang, Yingying Zhang, Xian Wu, and Xiao Zhou. 2026. Controllable Affective Generation via Latent Vector Steering. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 36494–36510, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Controllable Affective Generation via Latent Vector Steering (Yong et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1707.pdf