Beyond Semantics: Measuring Fine-Grained Emotion Preservation in Small Language Model-Based Machine Translation

arXiv cs.CL / 5/1/2026

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Key Points

  • The paper tests how well three small language models (EuroLLM, Aya Expanse, and Gemma) preserve fine-grained emotional nuance in machine translation, where semantics are often prioritized over affect.
  • It uses the GoEmotions dataset (Reddit comments labeled into 28 emotion categories) to evaluate emotion preservation across five European languages via a backtranslation setup.
  • The study examines whether the models’ inherent emotion-retention ability is sufficient, and whether emotion-aware prompting can further improve emotional fidelity.
  • It also assesses ModernBERT as a contemporary alternative to BERT for emotion classification to support MT evaluation.
  • Overall, the work provides an evaluation framework and comparative results focused specifically on emotional preservation rather than only semantic equivalence.

Abstract

Preserving affective nuance remains a challenge in Machine Translation (MT), where semantic equivalence often takes precedence over emotional fidelity. This paper evaluates the performance of three state-of-the-art Small Language Models (SLMs) -- EuroLLM, Aya Expanse, and Gemma -- in maintaining fine-grained emotions during backtranslation. Using the GoEmotions dataset, which comprises Reddit comments across 28 distinct categories, we assess emotional preservation across five European languages: German, French, Spanish, Italian, and Polish. Specifically, we investigate (i) the inherent capability of these SLMs to retain emotional sentiment, (ii) the efficacy of emotion-aware prompting in improving preservation, and (iii) the performance of ModernBERT as a contemporary alternative to BERT for emotion classification in MT evaluation.