arXiv AI

Metonymic Circuits for Abstract Concept Grounding in Vision Transformers

The paper investigates how Vision Transformers (ViTs) ground abstract concepts such as "angry" when training data provide limited direct evidence. It proposes a metonymic grounding mechanism where abstract predictions are driven by concrete, interpretable anchor concepts like "fire" that bridge visual signals to abstract semantics. Using Transcoders on CLIP and DINO encoders, the authors recover intermediate features linked to concrete concepts and trace their contributions in circuits that recognize abstract concepts, revealing structured metonymic circuits and distinct perceptual-to-textual routes for images with rendered text.

arXiv Computer Vision
Oct 9

From What to Which: Decoding Modifier Grounding in Frozen MLLMs

The paper investigates whether frozen Multimodal Large Language Models (MLLMs) encode grounding information about specific visual instances within the tokens they generate, including modifiers such as attributes, spatial expressions, and relational terms. The authors introduce OTTER, a lightweight supervised probe that applies Optimal Transport to align generated tokens with visual regions, producing compact grounding maps. Experiments demonstrate that modifier tokens, especially spatial terms, carry instance‑discriminative visual information, that object nouns also encode referential cues, and that the recovered grounding remains robust to context changes and generalizes to free generation and cross‑dataset transfer.

By Barbara Toniella Corradini (AI for Good), Caterina Gallegati (University of Siena, Italy), Ludovica Genovese (AI for Good), Vittorio Murino (AI for Good)
arXiv Computation and Language
Oct 12

Vision Transformers Learn Word Meaning from Images Alone

The study demonstrates that large DINOv3 vision transformers, trained solely on images without any language supervision, can organize rendered words in their embedding space according to meaning. By deriving word representations from differences between word images and matched controls, the authors show that semantically related words cluster together, brand names group by industry, and country-capital pairs exhibit consistent vector offsets. These representations align with visual object categories and share structure with text and speech encoders, indicating that image-only training can impart both visual and semantic understanding of words.

By Anders Gj{\o}lbye, Sebastian Ray Mason, Stella Frank, Lars Kai Hansen
arXiv AI
Sep 17

Using OCR Heads to Verbalize Image Semantics

The paper investigates how vision‑language models (VLMs) perform optical character recognition (OCR) by identifying attention heads that are causally necessary for OCR across four models. These heads are shown to be general‑purpose, producing interpretable semantic features for any image token, such as recognizing the word "bike" or the concept "feathers". By collapsing the heads’ attention weights into a verbalization lens transformation, the authors reveal that image representations align with language from early layers and can even be used to edit non‑word concepts in images, demonstrating the broader utility of this subspace.

By Sheridan Feucht, Benno Krojer, Sarah Wang, Henry Abrahamsen, Byron C. Wallace, David Bau