arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2602.06218cs.CVcs.LG
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跨模态冗余与视觉-语言嵌入的几何学

Cross-Modal Redundancy and the Geometry of Vision-Language Embeddings

Brown University(布朗大学);ENS Paris Saclay(巴黎萨克雷大学);IRT Saint Exupéry(IRT圣埃克苏佩里);Kempner Institute, Harvard University(哈佛大学凯姆纳研究所)

Grégoire Dhimoïla, Thomas Fel, Victor Boutin, Agustin Picard

AI总结:

本文通过等能假设和对齐稀疏自编码器,揭示了视觉-语言模型中跨模态对齐的几何结构,发现稀疏双模态原子承载了跨模态对齐信号,单模态原子解释了模态差距,去除单模态原子可消除差距而不影响性能。

摘要:

视觉-语言模型(VLMs)在对齐图像和文本方面取得了显著成功,但其共享嵌入空间的几何结构仍然理解不足。为了探索这一几何结构,我们从等能假设出发,该假设利用了跨模态冗余:一个真正共享的概念应在不同模态中表现出相同的平均能量。我们通过一种对齐稀疏自编码器(SAE)来操作这一假设,该自编码器在训练过程中鼓励能量一致性,同时保持重建能力。我们发现这种归纳偏置改变了SAE的解决方案,而不会影响重建,从而得到一种可以用于几何分析的表示。在具有已知真实值的受控数据上进行的合理性检查证实,当等能成立时,对齐会得到改善,而当等能不成立时则保持中性。应用于基础VLMs时,我们的框架揭示了清晰的结构和实际影响:(i)稀疏双模态原子承载了全部跨模态对齐信号;(ii)单模态原子作为模态特定的偏差,并完全解释了模态差距;(iii)去除单模态原子会消除差距而不影响性能;(iv)将向量运算限制在双模态子空间内会产生分布内编辑和改进的检索。这些发现表明,正确的归纳偏置既能保持模型保真度,又能使潜在几何变得可解释和可操作。

英文摘要:

Vision-language models (VLMs) align images and text with remarkable success, yet the geometry of their shared embedding space remains poorly understood. To probe this geometry, we begin from the Iso-Energy Assumption, which exploits cross-modal redundancy: a concept that is truly shared should exhibit the same average energy across modalities. We operationalize this assumption with an Aligned Sparse Autoencoder (SAE) that encourages energy consistency during training while preserving reconstruction. We find that this inductive bias changes the SAE solution without harming reconstruction, giving us a representation that serves as a tool for geometric analysis. Sanity checks on controlled data with known ground truth confirm that alignment improves when Iso-Energy holds and remains neutral when it does not. Applied to foundational VLMs, our framework reveals a clear structure with practical consequences: (i) sparse bimodal atoms carry the entire cross-modal alignment signal; (ii) unimodal atoms act as modality-specific biases and fully explain the modality gap; (iii) removing unimodal atoms collapses the gap without harming performance; (iv) restricting vector arithmetic to the bimodal subspace yields in-distribution edits and improved retrieval. These findings suggest that the right inductive bias can both preserve model fidelity and render the latent geometry interpretable and actionable.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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