GraSP-VL: Length as a Semantic Granularity Interface for Vision-Language Representations

Lizesheng, Pan Chengchang, Honggang Qi


Abstract
Frozen vision-language models already encode object, attribute, relation, and caption information, but a single vector exposes all of these signals through the same access pattern. We ask whether vector length can become a semantic access control: short prefixes answer coarse queries, while longer prefixes add finer distinctions. GraSP-VL learns one shared near-orthogonal transform for image and text embeddings and assigns a fixed, configurable prefix contract. At inference, the transform is applied once and ordinary cosine retrieval uses the prefix required by the task. On a 20,147-example COCO/Flickr30K pool, GraSP-VL reaches a staircase score of 53.01 and hard-negative selectivity of 89.76 with full-space drift below 10-6. Full-dimensional ImageNet-V2 classification and Flickr30K/COCO Karpathy retrieval are unchanged, while held-out human-caption retrieval improves at shorter prefixes. These results show that length can reorganize access to frozen VLM semantics rather than merely compressing them. Code and project page are available at https://lizesheng13.github.io/Grasp-VL/.
Anthology ID:
2026.emnlp-main.344
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
7919–7935
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URL:
https://aclanthology.org/2026.emnlp-main.344/
DOI:
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Cite (ACL):
Lizesheng, Pan Chengchang, and Honggang Qi. 2026. GraSP-VL: Length as a Semantic Granularity Interface for Vision-Language Representations. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 7919–7935, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
GraSP-VL: Length as a Semantic Granularity Interface for Vision-Language Representations (Lizesheng et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.344.pdf