Towards A Scanpath-Conditioned Surprisal Theory: Modeling Reader Information States

Michael Mooney, Edmond S. L. Ho


Abstract
Standard surprisal is typically computed from the linear text prefix, but human reading is non-linear and memory constrained: readers skip words, regress, and do not retain prior context perfectly. We propose a formulation of surprisal conditioned on a reader-specific accessible information state given by the scanpath history and memory dynamics, rather than by the written prefix alone. Prior context is treated as only probabilistically accessible at each fixation, allowing predictability to depend on both non-linear exposure and forgetting. We evaluate the approach on eye-tracking corpora using held-out log-likelihood over standard duration based reading measures. Across model variants, conditioning on accessible information states improves predictive fit over standard surprisal baselines. These results suggest that predictability in human reading is better characterized relative to the reader’s evolving accessible information state than to the written prefix alone.
Anthology ID:
2026.acl-long.1919
Volume:
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
Venue:
ACL
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Publisher:
Association for Computational Linguistics
Note:
Pages:
41366–41380
Language:
URL:
https://preview.aclanthology.org/ingest-acl/2026.acl-long.1919/
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Bibkey:
Cite (ACL):
Michael Mooney and Edmond S. L. Ho. 2026. Towards A Scanpath-Conditioned Surprisal Theory: Modeling Reader Information States. In Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 41366–41380, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
Towards A Scanpath-Conditioned Surprisal Theory: Modeling Reader Information States (Mooney & Ho, ACL 2026)
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https://preview.aclanthology.org/ingest-acl/2026.acl-long.1919.pdf
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