Unified modelling of gaze and pupil dynamics in saccadic tasks.

Overview

1. Department of Optics, Pharmacology and Anatomy, Universidad de Alicante,Carretera San Vicente del Raspeig, s/n, San Vicente del Raspeig, 03690 Alicante, Spain
2. University Institute of Physics Applied to Sciences and Technologies, Universidad de Alicante,Carretera San Vicente del Raspeig, s/n, San Vicente del Raspeig, 03690 Alicante, Spain
3. Instituto Centro de Investigación Operativa, Universitas Miguel Hernández,Avenida de la Universidad, s/n, Elche, 03202 Alicante, Spain

Abstract

This study introduces a unified phenomenological framework to characterize the interconnected dynamics of gaze displacement and pupillary area variation during large-amplitude (30°) horizontal saccades. Using a high-resolution dataset from 242 healthy participants, we modeled primary saccadic shifts and post-saccadic oscillations (PSO) using a combined sigmoidal Boltzmann and damped harmonic oscillator approach. Our framework demonstrates that even after correcting for pupil foreshortening error, the pupillary signal contains physiological PSO-like oscillations that mirror gaze dynamics—a phenomenon previously uncharacterized in the literature. To account for the non-normal, heavy-tailed distribution of oculomotor parameters, population characteristics were defined using t location-scale modeling. Non-parametric Wilcoxon signed-rank tests revealed significant directional asymmetries; specifically, leftward movements exhibited longer total durations (∆t) and slower stabilization compared to rightward shifts. However, mechanical parameters such as oscillation amplitude and gaze baseline offsets remained directionally invariant (p > 0.01), suggesting a decoupling between asymmetric neural motor preparation and symmetrical biomechanical constraints. By establishing high-precision baseline parameters in an extensive population, this model provides a foundation for using joint gaze-pupil signatures as sensitive biomarkers for detecting subtle oculomotor and autonomic dysfunctions.

Reproduced under the paper's license (CC BY), from the paper cited above.

Code

No file of the authors' code could be read here: it is described below, and read at its source.

Code availability

The custom MATLAB code used to implement the PFE correction procedure, the curve-fitting routines for the Boltzmann sigmoid and damped harmonic oscillator models (Eqs. 2 and 3), the quality filtering and trial-balancing pipeline, the population distribution fitting, and the subject-level statistical comparisons is publicly available at the Institutional Repository of the University of Alicante: http://hdl.handle.net/10045/164099. The MNH saccade detection algorithm applied upstream was used as originally described by Friedman et al.30 and Nyström and Holmqvist31; no modifications were made to that algorithm. All analyses were performed using MATLAB (R2020b or later) with the Curve Fitting Toolbox, the Statistics and Machine Learning Toolbox, and the Signal Processing Toolbox.

Reproduced under the paper's license (CC BY), from the paper cited above.

Tracing map

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Data

No dataset and no data link were found in the paper.

Data availability

This study uses data from the Horizontal Saccade Task (HSS), collected from 309 participants in the GazeBase dataset (licensed under CC BY 4.0), as described by Griffith, H., Lohr, D., Abdulin, E. & Komogortsev, O. “GazeBase, a large-scale, multi-stimulus, longitudinal eye movement dataset,” Sci Data 8, 184 (2021). The extracted eye movement sequences and derived parameters used in this work are publicly available at the Institutional Repository of the University of Alicante, http://hdl.handle.net/10045/155507.

Reproduced under the paper's license (CC BY), from the paper cited above.

Versions

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Version 1, 27 September 2026: the first record

Recorded: type, language, journal, volume, issue, pages, dates, 4 authors, 6 keywords, 8 MeSH terms, 54 references.

Cite

This paper

Espinosa, J., Guisot, M., Larrosa, A., & Pérez, J. (2026). Unified modelling of gaze and pupil dynamics in saccadic tasks. Scientific reports, 16(1), 20267. https://doi.org/10.1038/s41598-026-51489-9

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