On the Geometry of Multimodal Saturation: Riemannian VICReg

arXiv:2610.06096 · cs.LG, cs.AI · Submitted 2026-10-05 · Read on arXiv

cs.LG, cs.AI

Submitted: 2026-10-05

Updated: 2026-10-05

Comments: 17 pages, 6 figures. Accepted to the Proceedings Track of the NeurIPS 2026 Workshop on Symmetry and Geometry in Neural Representations (NeurReps)

License: http://creativecommons.org/licenses/by-nc-nd/4.0/

The gist: In self-supervised learning, a third modality should improve, or at least preserve, performance.

Abstract

In self-supervised learning, a third modality should improve, or at least preserve, performance. Across nine image-text-tabular datasets, we show that it instead harms performance: the trimodal model underperforms its own best bimodal subset in 55.6% of paired runs under VICReg. The same failure occurs in 51.1% of paired runs under SimSiam. We call this failure multimodal saturation. We propose that the failure lies in the alignment geometry. Riemannian VICReg (R-VICReg) generalizes classical VICReg: it aligns views by squared geodesic distance on learnable negative-curvature product factors and recovers VICReg exactly as curvature vanishes. Over the same 45 paired runs, R-VICReg raises the probability that the third modality helps from 44.4% to 64.4%, with gains concentrated where VICReg saturates.

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