Subliminal Clocks: Latent Time Modelling in Diffusion Language Models

Maximo Rulli, Thomas V. Fontanari, Simone Petruzzi, Federico Alvetreti, Giorgio Strano, Donato Crisostomi, Giorgos Nikolaou, Tommaso Mencattini, Andrea Santilli, Emanuele Rodolà, Simone Scardapane, Alessio Devoto


Abstract
Masked Diffusion Language Models (MDLMs) have recently emerged as a promising alternative to autoregressive models. Unlike standard diffusion-based approaches, MDLMs are not explicitly conditioned on a timestep, raising a natural question: do these models internally represent denoising progress, and how is such information used downstream? In this work, we show that MDLMs do in fact encode a latent representation related to the diffusion timestep within their residual streams. We find that this signal can be reliably extracted using probes across layers, indicating that denoising progress is decodable from internal activations. We further demonstrate that steering the model along a low-dimensional subspace associated with the inferred timestep allows us to systematically modulate its notion of denoising progress, leading to controlled and predictable changes in model confidence and entropy. Finally, we analyse the geometry of the identified representation, showing that it exhibits structured and interpretable properties in activation space, and shedding light on how such a signal is manipulated by these models.
Anthology ID:
2026.emnlp-main.1749
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
Note:
Pages:
39904–39927
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URL:
https://aclanthology.org/2026.emnlp-main.1749/
DOI:
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Cite (ACL):
Maximo Rulli, Thomas V. Fontanari, Simone Petruzzi, Federico Alvetreti, Giorgio Strano, Donato Crisostomi, Giorgos Nikolaou, Tommaso Mencattini, Andrea Santilli, Emanuele Rodolà, Simone Scardapane, and Alessio Devoto. 2026. Subliminal Clocks: Latent Time Modelling in Diffusion Language Models. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 39904–39927, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Subliminal Clocks: Latent Time Modelling in Diffusion Language Models (Rulli et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.1749.pdf