Yiming Zhang, Zhonghan Zhao, Wenwei Zhang, Haiteng Zhao, Tianyang Lin, Yunhua Zhou, Demin Song, Kuikun Liu, Haochen Ye, Haian Huang, Yuzhe Gu, Haijun Lv, Qipeng Guo, Bin Liu, Gaoang Wang, Kai Chen
6 min
Modern foundation models are almost exclusively trained on text corpora, assuming that all essential knowledge can be represented as a linear sequence of tokens. This paper challenges this assumption, arguing that scientific documents contain critical information—such as complex equations, figures, and spatial layouts—that is inherently lost or distorted when documents are converted into plain text via OCR or parsing tools. The authors investigate whether training models directly on raw visual document pages can yield superior language and reasoning intelligence.
To test this, the authors introduce Visual Pretraining (VP), an unsupervised framework that trains models to predict document patches in a latent space without requiring explicit image-text pairing or text extraction. They conduct a systematic, controlled comparison between VP and traditional Text Pretraining (TP) using identical underlying scientific document corpora. By keeping the starting checkpoints and supervised fine-tuning (SFT) data constant, they isolate the impact of preserving the native visual structure of the documents.
This work demonstrates that the "text-only" paradigm for foundation models is likely suboptimal for scientific and technical domains. By treating raw visual documents as a primary data source, researchers can unlock richer, more structured representations that enhance both logical reasoning and multimodal capabilities. This provides a scalable, efficient pathway for building more capable AI systems that can interpret the world as it is presented in technical literature.
The rapid progress of large foundation models has been driven predominantly by pretraining on large-scale text corpora. However, many forms of knowledge are conveyed through visual representations, where figures, typeset equations, and page layouts carry rich information that cannot be faithfully or completely captured by text alone. Yet current pretraining approaches discard these visual cues by converting visually rich sources, such as documents and web pages, into plain text for learning language intelligence. This paper challenges the default assumption that language models must be trained on text-only representations and shows that Visual Pretraining is a scalable learner for foundation model intelligence. To this end, we conduct a systematic study of unsupervised visual pretraining paradigms that directly leverage visual documents without text extraction. Across multiple backbones and benchmarks, visual pretraining on the same underlying corpora consistently outperforms text-only pretraining, offering an efficient pathway to scalable language intelligence.
Alex: That's a meaningful gap. You also mentioned something called "cross-modal alignment" earlier. Can you unpack that?
Sam: Sure. Imagine a student reading a lab report. A weaker student might read the text and look at the graph separately, treating them as two different things. A stronger student understands that the graph is the argument — it's the visual proof of what the text is claiming. Cross-modal alignment is the model developing that stronger student's ability. Because it sees the text and the diagram together as one coherent structure on a page, it learns how they support each other. The visual and textual information become unified in the model's understanding, rather than two separate streams it has to manually connect later.
Alex: So the visual layout isn't just decoration — it's carrying part of the scientific argument itself. And by throwing it away, we were asking models to reason with an incomplete picture.
Sam: That's precisely the paper's central claim. And it's worth sitting with, because it has implications for how we think about what "reading" even means for an AI system.
Alex: But here's a question I'd want answered before accepting this: how do we know the gains come from the visual layout specifically, and not just from the model seeing more information in general?
Sam: The researchers addressed this directly. After the initial training phase, they put all the models through an identical set of practice tasks — a process called "Supervised Fine-Tuning," where every model gets the same follow-up instruction regardless of how it was originally trained. It's a level playing field. And even then, the models that had learned from raw page images consistently outperformed the text-only ones. That's the key control: same documents, same fine-tuning, different training signal. The difference in performance points back to the visual structure itself.
Alex: So the layout was doing real cognitive work, and stripping it out was a genuine loss — not just an aesthetic one.
Sam: Right. And the effect is strongest with documents that are visually dense — pages packed with figures, equations, and tables. The more visual structure a document contains, the larger the performance gap between the two approaches. Which makes sense: those are exactly the documents where the plain-text conversion loses the most.
Alex: Are there any practical complications with this approach? It sounds cleaner in theory, but training on images must be more demanding than training on text.
Sam: It is more complex. Managing the number of visual patches the model processes at once requires careful tuning. Push too many patches through at the same time and the training becomes unstable — the model struggles to learn reliably. There's a sweet spot, and finding it is a genuine engineering challenge. So while the approach is a meaningful step forward, the implementation details still require significant care.
Alex: It's a reminder that even when the core idea is sound, making it work in practice is its own problem.
Sam: Always. But the core finding here is worth taking seriously. For decades, the assumption has been that text is the universal language of knowledge — that if you can write it down, you can train on it. This research suggests that for scientific material especially, the way something is written down, the visual structure of the page itself, carries meaning that words alone cannot fully convey. Models that learn to see that structure appear to reason more effectively as a result.
Alex: It's a thought-provoking challenge to a very deep assumption in the field. Thanks for walking us through it, Sam, and thanks to everyone for listening to ResearchPod.