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Paper Abstract and Keywords
Presentation 2026-02-28 16:30
Learning Emotional Direction Vectors for Steering Japanese Large Language Models
Miyui Soga, Hiroaki Nanjo (Siga Univ.) NLC2025-13
Abstract (in Japanese) (See Japanese page) 
(in English) We propose an emotion control method for Japanese large language models (LLMs) based on Plutchik’s wheel of emotions. First, emotion direction vectors are extracted via binary classification probing with logistic regression on four opposing emotion pairs defined in Plutchik’s model: joy–sadness, surprise–anticipation, trust–disgust, and anger–fear. The probing uses hidden states extracted from each layer of the LLM in response to texts annotated with emotion labels. The results show that F1 scores generally increase with network depth across all emotion pairs, with a particularly sharp improvement observed around layer 13.
Next, we control the emotions expressed in generated text by adding the extracted emotion direction vectors as steering vectors to the hidden states during inference. For single emotion axes, more stable control effects are observed for the joy–sadness and surprise–anticipation axes compared to the other emotion pairs. Furthermore, we explore the control of composite emotions by linearly combining multiple emotion axis vectors, which reveals both the potential and the challenges of this approach.
Keyword (in Japanese) (See Japanese page) 
(in English) large language model / Emotion Steering / Activation Engineering / Probing / / / /  
Reference Info. IEICE Tech. Rep., vol. 125, no. 366, NLC2025-13, pp. 7-12, Feb. 2026.
Paper # NLC2025-13 
Date of Issue 2026-02-21 (NLC) 
ISSN Online edition: ISSN 2432-6380
Copyright
and
reproduction		 All rights are reserved and no part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher. Notwithstanding, instructors are permitted to photocopy isolated articles for noncommercial classroom use without fee. (License No.: 10GA0019/12GB0052/13GB0056/17GB0034/18GB0034)
Download PDF NLC2025-13

Conference Information
Committee NLC  
Conference Date 2026-02-28 - 2026-03-01 
Place (in Japanese) (See Japanese page) 
Place (in English)  
Topics (in Japanese) (See Japanese page) 
Topics (in English)  
Paper Information
Registration To NLC 
Conference Code 2026-03-NLC 
Language Japanese 
Title (in Japanese) (See Japanese page) 
Sub Title (in Japanese) (See Japanese page) 
Title (in English) Learning Emotional Direction Vectors for Steering Japanese Large Language Models 
Sub Title (in English)  
Keyword(1) large language model  
Keyword(2) Emotion Steering  
Keyword(3) Activation Engineering  
Keyword(4) Probing  
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1st Author's Name Miyui Soga  
1st Author's Affiliation Siga University (Siga Univ.)
2nd Author's Name Hiroaki Nanjo  
2nd Author's Affiliation Siga University (Siga Univ.)
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Speaker Author-1 
Date Time 2026-02-28 16:30:00 
Presentation Time 25 minutes 
Registration for NLC 
Paper # NLC2025-13 
Volume (vol) vol.125 
Number (no) no.366 
Page pp.7-12 
#Pages 6 
Date of Issue 2026-02-21 (NLC) 

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