Script Sensitivity: Benchmarking Language Models on Unicode, Romanized and Mixed-Script Sinhala

Fuente: arXiv
Saved in:
Bibliographic Details
Main Authors: Rajapakse, Minuri, Weerasinghe, Ruvan
Format: Preprint
Published: 2026
Subjects:
Online Access:
Tags: Add Tag
No Tags, Be the first to tag this record!
_version_ 1866909024393363456
author Rajapakse, Minuri
Weerasinghe, Ruvan
author_facet Rajapakse, Minuri
Weerasinghe, Ruvan
contents The performance of Language Models (LMs) on low-resource, morphologically rich languages like Sinhala remains largely unexplored, particularly regarding script variation in digital communication. Sinhala exhibits script duality, with Unicode used in formal contexts and Romanized text dominating social media, while mixed-script usage is common in practice. This paper benchmarks 24 open-source LMs on Unicode, Romanized and mixed-script Sinhala using perplexity evaluation across diverse text sources. Results reveal substantial script sensitivity, with median performance degradation exceeding 300 times from Unicode to Romanized text. Critically, model size shows no correlation with script-handling competence, as smaller models often outperform architectures 28 times larger. Unicode performance strongly predicts mixed-script robustness but not Romanized capability, demonstrating that single-script evaluation substantially underestimates real-world deployment challenges. These findings establish baseline LM capabilities for Sinhala and provide practical guidance for model selection in multi-script low-resource environments.
format Preprint
id arxiv_https___arxiv_org_abs_2601_14958
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Script Sensitivity: Benchmarking Language Models on Unicode, Romanized and Mixed-Script Sinhala
Rajapakse, Minuri
Weerasinghe, Ruvan
Computation and Language
Artificial Intelligence
The performance of Language Models (LMs) on low-resource, morphologically rich languages like Sinhala remains largely unexplored, particularly regarding script variation in digital communication. Sinhala exhibits script duality, with Unicode used in formal contexts and Romanized text dominating social media, while mixed-script usage is common in practice. This paper benchmarks 24 open-source LMs on Unicode, Romanized and mixed-script Sinhala using perplexity evaluation across diverse text sources. Results reveal substantial script sensitivity, with median performance degradation exceeding 300 times from Unicode to Romanized text. Critically, model size shows no correlation with script-handling competence, as smaller models often outperform architectures 28 times larger. Unicode performance strongly predicts mixed-script robustness but not Romanized capability, demonstrating that single-script evaluation substantially underestimates real-world deployment challenges. These findings establish baseline LM capabilities for Sinhala and provide practical guidance for model selection in multi-script low-resource environments.
title Script Sensitivity: Benchmarking Language Models on Unicode, Romanized and Mixed-Script Sinhala
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2601.14958