Not Truly Multilingual: Script Consistency as a Missing Dimension in VLM Evaluation

Prabhjot Singh, Bhushan Pawar, Madhu Reddiboina, Rajvee Sheth


Abstract
Current multilingual evaluations for Vision-Language Models (VLMs) assume a one-to-one mapping between language and orthography, overlooking billions of users of multi-script languages. We introduce PuMVR (Punjabi Multimodal Visual Reasoning), a benchmark of 1,000 strictly parallel image-text instances across Punjabi’s three active scripts: Gurmukhi, Shahmukhi, and Roman. Evaluating 10 state-of-the-art VLMs, we expose a substantial and systematic Script Gap. Models frequently solve visual tasks in one script while failing identical tasks in another, with accuracy deltas reaching 16%. Crucially, visual input boosts absolute performance uniformly yet does not close the orthographic gap. Furthermore, cross-script in-context transfer is highly brittle, exposing script-locked knowledge representation. Supported by McNemar tests across all script pairs, our findings demonstrate that current "multilingual" VLMs are not truly multi-script. We propose the Script Consistency Rate (SCR), which falls as low as 24.8% on our benchmark, as a mandatory metric for script-agnostic evaluation to ensure equitable AI access.
Anthology ID:
2026.findings-emnlp.232
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
4893–4909
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.232/
DOI:
Bibkey:
Cite (ACL):
Prabhjot Singh, Bhushan Pawar, Madhu Reddiboina, and Rajvee Sheth. 2026. Not Truly Multilingual: Script Consistency as a Missing Dimension in VLM Evaluation. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 4893–4909, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Not Truly Multilingual: Script Consistency as a Missing Dimension in VLM Evaluation (Singh et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.232.pdf