GTS: Inference-Time Scaling of Latent Reasoning with a Learnable Gaussian Thought Sampler

Minghan Wang, Ye Bai, Thuy-Trang Vu, Ehsan Shareghi, Gholamreza Haffari


Abstract
Inference-time scaling (ITS) for latent reasoning requires sampling multiple candidate latent trajectories, yet current methods typically rely on heuristic perturbations such as dropout or fixed Gaussian noise. We show that stronger perturbations do not necessarily improve candidate-set quality: they often induce larger distribution shifts without producing more decision-useful reasoning paths. This limitation arises because heuristic perturbations inject stochasticity through fixed or hand-designed mechanisms rather than an optimizable, context-conditioned sampling policy, making latent exploration difficult to control. We focus on the sampling side of latent ITS and propose the Gaussian Thought Sampler (GTS), a lightweight module that predicts context-dependent Gaussian perturbations over continuous reasoning states. Trained with GRPO-style policy optimization while keeping the backbone frozen, GTS turns heuristic perturbation into a trainable, context-conditioned sampling policy. Experiments across two latent reasoning backbones and multiple benchmarks show that GTS consistently improves pass@N over heuristic baselines, suggesting that effective sampling for latent ITS requires controlled, optimizable exploration rather than simply amplified stochasticity.
Anthology ID:
2026.emnlp-main.341
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:
7861–7884
Language:
URL:
https://aclanthology.org/2026.emnlp-main.341/
DOI:
Bibkey:
Cite (ACL):
Minghan Wang, Ye Bai, Thuy-Trang Vu, Ehsan Shareghi, and Gholamreza Haffari. 2026. GTS: Inference-Time Scaling of Latent Reasoning with a Learnable Gaussian Thought Sampler. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 7861–7884, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
GTS: Inference-Time Scaling of Latent Reasoning with a Learnable Gaussian Thought Sampler (Wang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.341.pdf