Culturally-Aware Image Captioning for Guaraní with Multimodal Prompting: IUHoosiers at AmericasNLP 2026

Wenchen Shi, Phakphum Artkaew, Luke Gessler


Abstract
The AmericasNLP 2026 shared task challenges systems to generate culturally grounded image captions in indigenous languages of the Americas, a setting that demands both cultural awareness and linguistic accuracy for severely underresourced languages. We present IUHoosiers, Indiana University’s system for the Guaraní track. Rather than fine-tuning, our approach centers on inference-time knowledge injection: for each test image, we retrieve relevant Guaraní grammatical and cultural resources using BM25 and inject them into a large vision language model’s prompt alongside the image, enabling language-specific cultural and linguistic grounding without any parameter updates. IUHoosiers placed first for Guaraní in both automatic evaluation (24.67 chrF++) and human evaluation (3.45/5), outperforming all other participating systems.
Anthology ID:
2026.americasnlp-6.21
Volume:
Proceedings of the Sixth Workshop on NLP for Indigenous Languages of the Americas (AmericasNLP)
Month:
July
Year:
2026
Address:
San Diego, California, USA
Editors:
Manuel Mager, Abteen Ebrahimi, Minh Duc Bui, Robert Pugh, Arturo Oncevay, Luis Chiruzzo, Rolando Coto Solano, Shruti Rijhwani, Katharina Von Der Wense
Venues:
AmericasNLP | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
236–242
Language:
URL:
https://preview.aclanthology.org/ingest-acl-workshops/2026.americasnlp-6.21/
DOI:
Bibkey:
Cite (ACL):
Wenchen Shi, Phakphum Artkaew, and Luke Gessler. 2026. Culturally-Aware Image Captioning for Guaraní with Multimodal Prompting: IUHoosiers at AmericasNLP 2026. In Proceedings of the Sixth Workshop on NLP for Indigenous Languages of the Americas (AmericasNLP), pages 236–242, San Diego, California, USA. Association for Computational Linguistics.
Cite (Informal):
Culturally-Aware Image Captioning for Guaraní with Multimodal Prompting: IUHoosiers at AmericasNLP 2026 (Shi et al., AmericasNLP 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl-workshops/2026.americasnlp-6.21.pdf
Supplementarymaterial:
 2026.americasnlp-6.21.SupplementaryMaterial.zip