Target-Side Paraphrase Augmentation for Sign Language Translation with Large Language Models

Fuente: arXiv
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Auteurs principaux: Bianco, Pedro Dal, Reinhold, Jean Paul Nunes, Stanchi, Oscar, Quiroga, Facundo, Ronchetti, Franco, Corrêa, Ulisses Brisolara
Format: Preprint
Publié: 2026
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author Bianco, Pedro Dal
Reinhold, Jean Paul Nunes
Stanchi, Oscar
Quiroga, Facundo
Ronchetti, Franco
Corrêa, Ulisses Brisolara
author_facet Bianco, Pedro Dal
Reinhold, Jean Paul Nunes
Stanchi, Oscar
Quiroga, Facundo
Ronchetti, Franco
Corrêa, Ulisses Brisolara
contents Sign language translation (SLT) remains constrained by limited paired sign-video/text corpora and heavy-tailed target vocabularies. We study target-side augmentation in which GPT-4o generates controlled paraphrase variants of reference sentences while the sign input remains unchanged. A Signformer-style pose-based Transformer is trained under a two-stage schedule: pre-training on the augmented corpus followed by fine-tuning on the original references. We evaluate on three datasets spanning complementary challenges: PHOENIX14T (German Sign Language), with moderate lexical diversity; GSL (Greek Sign Language), with highly ontrolled, repetitive recordings; and LSA-T (Argentinian Sign Language), with severe long-tail sparsity. On PHOENIX14T, augmentation improves BLEU-4 from 9.56 to 10.33. The near-saturated GSL baseline and extremely sparse LSA-T setting reveal the limits of the approach. To our knowledge, this is the first study to apply LLM-generated target-side araphrases and LLM-as-a-Judge evaluation to SLT. The semantic evaluation reveals gains in fidelity that lexical overlap metrics understate.
format Preprint
id arxiv_https___arxiv_org_abs_2605_31393
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Target-Side Paraphrase Augmentation for Sign Language Translation with Large Language Models
Bianco, Pedro Dal
Reinhold, Jean Paul Nunes
Stanchi, Oscar
Quiroga, Facundo
Ronchetti, Franco
Corrêa, Ulisses Brisolara
Computation and Language
Artificial Intelligence
Sign language translation (SLT) remains constrained by limited paired sign-video/text corpora and heavy-tailed target vocabularies. We study target-side augmentation in which GPT-4o generates controlled paraphrase variants of reference sentences while the sign input remains unchanged. A Signformer-style pose-based Transformer is trained under a two-stage schedule: pre-training on the augmented corpus followed by fine-tuning on the original references. We evaluate on three datasets spanning complementary challenges: PHOENIX14T (German Sign Language), with moderate lexical diversity; GSL (Greek Sign Language), with highly ontrolled, repetitive recordings; and LSA-T (Argentinian Sign Language), with severe long-tail sparsity. On PHOENIX14T, augmentation improves BLEU-4 from 9.56 to 10.33. The near-saturated GSL baseline and extremely sparse LSA-T setting reveal the limits of the approach. To our knowledge, this is the first study to apply LLM-generated target-side araphrases and LLM-as-a-Judge evaluation to SLT. The semantic evaluation reveals gains in fidelity that lexical overlap metrics understate.
title Target-Side Paraphrase Augmentation for Sign Language Translation with Large Language Models
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2605.31393