@inproceedings{chintada-etal-2026-orthogonal,
title = "Orthogonal Style Injection: Mechanistic Persona Steering for Zero-Shot Cross-Lingual Subtitle Translation",
author = "Chintada, Tarun and
Singh, Kshetrimayum Boynao and
Ekbal, Asif",
editor = "Zhang, Yue and
Xu, Ruifeng and
Purwarianti, Ayu and
Rong, Tong and
Suzuki, Jun",
booktitle = "Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the {A}sia-Pacific Chapter of the {A}ssociation for {C}omputational {L}inguistics (Volume 1: Long Papers)",
month = nov,
year = "2026",
address = "Hengqin, China",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.aacl-long.274/",
pages = "6058--6084",
ISBN = "979-8-89176-439-2",
abstract = "In conversational and cinematic subtitle translation, large language models often exhibit stylistic collapse, defaulting to neutral registers that flatten character-specific personas. Prompt-based attempts to recover style frequently introduce instruction drift and semantic degradation. We propose Orthogonal Style Injection (OSI), a parameter-efficient, inference-time intervention that removes global stylistic bias through orthogonal projection at an intermediate layer and injects a character-specific style vector derived solely from English source dialogue. We evaluate OSI for English-to-Bengali, Hindi, Telugu, Tamil, Kannada, Chinese, Japanese, Spanish, French, German, and Italian subtitle translation, spanning 11 typologically diverse target languages. Results show that zero-shot stylistic transfer depends strongly on pretraining alignment. Llama-3.1-8B yields gains in several European languages but degrades on Indic languages, whereas Qwen-2.5-7B transfers style more robustly across Indic and East Asian languages. To probe sociolinguistic mechanisms, we curate a parallel English-Bengali cinematic dataset as a focused morphological stress test. Automatic metrics and human evaluation show that OSI enables meaningful honorific and register shifts while largely preserving semantic fidelity, revealing a dataset-dependent trade-off between stylistic fidelity and translation quality in highly colloquial, morphologically constrained settings."
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<abstract>In conversational and cinematic subtitle translation, large language models often exhibit stylistic collapse, defaulting to neutral registers that flatten character-specific personas. Prompt-based attempts to recover style frequently introduce instruction drift and semantic degradation. We propose Orthogonal Style Injection (OSI), a parameter-efficient, inference-time intervention that removes global stylistic bias through orthogonal projection at an intermediate layer and injects a character-specific style vector derived solely from English source dialogue. We evaluate OSI for English-to-Bengali, Hindi, Telugu, Tamil, Kannada, Chinese, Japanese, Spanish, French, German, and Italian subtitle translation, spanning 11 typologically diverse target languages. Results show that zero-shot stylistic transfer depends strongly on pretraining alignment. Llama-3.1-8B yields gains in several European languages but degrades on Indic languages, whereas Qwen-2.5-7B transfers style more robustly across Indic and East Asian languages. To probe sociolinguistic mechanisms, we curate a parallel English-Bengali cinematic dataset as a focused morphological stress test. Automatic metrics and human evaluation show that OSI enables meaningful honorific and register shifts while largely preserving semantic fidelity, revealing a dataset-dependent trade-off between stylistic fidelity and translation quality in highly colloquial, morphologically constrained settings.</abstract>
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%0 Conference Proceedings
%T Orthogonal Style Injection: Mechanistic Persona Steering for Zero-Shot Cross-Lingual Subtitle Translation
%A Chintada, Tarun
%A Singh, Kshetrimayum Boynao
%A Ekbal, Asif
%Y Zhang, Yue
%Y Xu, Ruifeng
%Y Purwarianti, Ayu
%Y Rong, Tong
%Y Suzuki, Jun
%S Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
%D 2026
%8 November
%I Association for Computational Linguistics
%C Hengqin, China
%@ 979-8-89176-439-2
%F chintada-etal-2026-orthogonal
%X In conversational and cinematic subtitle translation, large language models often exhibit stylistic collapse, defaulting to neutral registers that flatten character-specific personas. Prompt-based attempts to recover style frequently introduce instruction drift and semantic degradation. We propose Orthogonal Style Injection (OSI), a parameter-efficient, inference-time intervention that removes global stylistic bias through orthogonal projection at an intermediate layer and injects a character-specific style vector derived solely from English source dialogue. We evaluate OSI for English-to-Bengali, Hindi, Telugu, Tamil, Kannada, Chinese, Japanese, Spanish, French, German, and Italian subtitle translation, spanning 11 typologically diverse target languages. Results show that zero-shot stylistic transfer depends strongly on pretraining alignment. Llama-3.1-8B yields gains in several European languages but degrades on Indic languages, whereas Qwen-2.5-7B transfers style more robustly across Indic and East Asian languages. To probe sociolinguistic mechanisms, we curate a parallel English-Bengali cinematic dataset as a focused morphological stress test. Automatic metrics and human evaluation show that OSI enables meaningful honorific and register shifts while largely preserving semantic fidelity, revealing a dataset-dependent trade-off between stylistic fidelity and translation quality in highly colloquial, morphologically constrained settings.
%U https://aclanthology.org/2026.aacl-long.274/
%P 6058-6084
Markdown (Informal)
[Orthogonal Style Injection: Mechanistic Persona Steering for Zero-Shot Cross-Lingual Subtitle Translation](https://aclanthology.org/2026.aacl-long.274/) (Chintada et al., AACL-IJCNLP 2026)
ACL