A Universal Vibe? Finding and Controlling Language-Agnostic Informal Register with SAEs

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Hauptverfasser: Kialy, Uri Z., Shtarkberg, Avi, Klein, Ayal
Format: Preprint
Veröffentlicht: 2026
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author Kialy, Uri Z.
Shtarkberg, Avi
Klein, Ayal
author_facet Kialy, Uri Z.
Shtarkberg, Avi
Klein, Ayal
contents While multilingual language models successfully transfer factual and syntactic knowledge across languages, it remains unclear whether they process culture-specific pragmatic registers, such as slang, as isolated language-specific memorizations or as unified, abstract concepts. We study this by probing the internal representations of Gemma-2-9B-IT using Sparse Autoencoders (SAEs) across three typologically diverse source languages: English, Hebrew, and Russian. To definitively isolate pragmatic register processing from trivial lexical sensitivity, we introduce a novel dataset in which every target term is polysemous, appearing in both literal and informal contexts. We find that while much of the informal-register signal is distributed across language-specific features, a small but highly robust cross-linguistic core consistently emerges. This shared core forms a geometrically coherent ``informal register subspace'' that sharpens in the model's deeper layers. Crucially, these shared representations are not merely correlational: activation steering with these features causally shifts output formality across all source languages and transfers zero-shot to six unseen languages spanning diverse language families and scripts. Together, these results provide the first mechanistic evidence that multilingual LLMs internalize informal register not just as surface-level heuristics, but as a portable, language-agnostic pragmatic abstraction.
format Preprint
id arxiv_https___arxiv_org_abs_2603_26236
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A Universal Vibe? Finding and Controlling Language-Agnostic Informal Register with SAEs
Kialy, Uri Z.
Shtarkberg, Avi
Klein, Ayal
Computation and Language
While multilingual language models successfully transfer factual and syntactic knowledge across languages, it remains unclear whether they process culture-specific pragmatic registers, such as slang, as isolated language-specific memorizations or as unified, abstract concepts. We study this by probing the internal representations of Gemma-2-9B-IT using Sparse Autoencoders (SAEs) across three typologically diverse source languages: English, Hebrew, and Russian. To definitively isolate pragmatic register processing from trivial lexical sensitivity, we introduce a novel dataset in which every target term is polysemous, appearing in both literal and informal contexts. We find that while much of the informal-register signal is distributed across language-specific features, a small but highly robust cross-linguistic core consistently emerges. This shared core forms a geometrically coherent ``informal register subspace'' that sharpens in the model's deeper layers. Crucially, these shared representations are not merely correlational: activation steering with these features causally shifts output formality across all source languages and transfers zero-shot to six unseen languages spanning diverse language families and scripts. Together, these results provide the first mechanistic evidence that multilingual LLMs internalize informal register not just as surface-level heuristics, but as a portable, language-agnostic pragmatic abstraction.
title A Universal Vibe? Finding and Controlling Language-Agnostic Informal Register with SAEs
topic Computation and Language
url https://arxiv.org/abs/2603.26236