Donors and Recipients: On Asymmetric Transfer Across Tasks and Languages with Parameter-Efficient Fine-Tuning

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Hauptverfasser: Dymkiewicz, Kajetan, Vulic, Ivan, Yannakoudakis, Helen, Shapira, Eilam, Reichart, Roi, Korhonen, Anna
Format: Preprint
Veröffentlicht: 2025
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author Dymkiewicz, Kajetan
Vulic, Ivan
Yannakoudakis, Helen
Shapira, Eilam
Reichart, Roi
Korhonen, Anna
author_facet Dymkiewicz, Kajetan
Vulic, Ivan
Yannakoudakis, Helen
Shapira, Eilam
Reichart, Roi
Korhonen, Anna
contents Large language models (LLMs) perform strongly across tasks and languages, yet how improvements in one task or language affect other tasks and languages remains poorly understood. We conduct a controlled LoRA fine-tuning study across multiple open-weight LLM families and scales, using a standardised grid of 11 languages and four benchmarks. We fine-tune each model on a single task-language source and measure transfer when evaluated on all other task-language target pairs. We decompose transfer into three regimes: (i) Matched-Task (Cross-Language), (ii) Matched-Language (Cross-Task), and (iii) Cross-Task (Cross-Language). Single-source fine-tuning yields a net positive uplift across regimes, but the gains are strongly asymmetric. Matched-Task (Cross-Language) transfer emerges as the most effective and predictable regime, driven principally by the identity of the target language rather than model architecture. We identify a stable hierarchy where high-resource languages and broad semantic tasks act as efficient recipients that absorb gains from diverse sources, while specialised tasks and lower-resource languages are more isolated. These results imply that effective fine-tuning requires navigating donor-recipient roles to maximise downstream gains.
format Preprint
id arxiv_https___arxiv_org_abs_2511_13368
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Donors and Recipients: On Asymmetric Transfer Across Tasks and Languages with Parameter-Efficient Fine-Tuning
Dymkiewicz, Kajetan
Vulic, Ivan
Yannakoudakis, Helen
Shapira, Eilam
Reichart, Roi
Korhonen, Anna
Computation and Language
Artificial Intelligence
Large language models (LLMs) perform strongly across tasks and languages, yet how improvements in one task or language affect other tasks and languages remains poorly understood. We conduct a controlled LoRA fine-tuning study across multiple open-weight LLM families and scales, using a standardised grid of 11 languages and four benchmarks. We fine-tune each model on a single task-language source and measure transfer when evaluated on all other task-language target pairs. We decompose transfer into three regimes: (i) Matched-Task (Cross-Language), (ii) Matched-Language (Cross-Task), and (iii) Cross-Task (Cross-Language). Single-source fine-tuning yields a net positive uplift across regimes, but the gains are strongly asymmetric. Matched-Task (Cross-Language) transfer emerges as the most effective and predictable regime, driven principally by the identity of the target language rather than model architecture. We identify a stable hierarchy where high-resource languages and broad semantic tasks act as efficient recipients that absorb gains from diverse sources, while specialised tasks and lower-resource languages are more isolated. These results imply that effective fine-tuning requires navigating donor-recipient roles to maximise downstream gains.
title Donors and Recipients: On Asymmetric Transfer Across Tasks and Languages with Parameter-Efficient Fine-Tuning
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2511.13368