Eyes on hold: motion task difficulty jointly delays microsaccade and pupil responses

Abstract Microsaccades and pupil dynamics exhibit canonical temporal profiles, providing insights into perceptual and cognitive processes. Microsaccades are typically suppressed with respect to expected stimulus onset and followed by a rebound to baseline rates. Here, we investigated whether and how...

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Main Authors: Rania Ezzo, Bogeng Song, Bas Rokers, Marisa Carrasco
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Scientific Reports
Subjects:
Online Access:https://doi.org/10.1038/s41598-025-04748-0
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author Rania Ezzo
Bogeng Song
Bas Rokers
Marisa Carrasco
author_facet Rania Ezzo
Bogeng Song
Bas Rokers
Marisa Carrasco
author_sort Rania Ezzo
collection DOAJ
description Abstract Microsaccades and pupil dynamics exhibit canonical temporal profiles, providing insights into perceptual and cognitive processes. Microsaccades are typically suppressed with respect to expected stimulus onset and followed by a rebound to baseline rates. Here, we investigated whether and how the temporal dynamics of microsaccades and pupil dilation vary with task difficulty for a motion perception task. We hypothesized that difficulty jointly delays the rebound of microsaccade rates and the time of peak pupil dilation when discriminating motion direction. Human observers discriminated motion direction (clockwise or counterclockwise) in a briefly presented perifoveal drifting stimulus, which varied according to two ‘easy’ vs ‘hard’ difficulty manipulations –cardinal vs oblique motion directions, and large vs small tilt offsets from the discriminated direction. We found that (1) increased task difficulty strengthened and prolonged microsaccade inhibition resulting in delayed rebounds, (2) peak pupillary responses were both larger in amplitude and delayed for more difficult conditions, (3) discrimination response time correlated with microsaccade rebounds and peak pupillary responses. We conclude that the delays in these microsaccade rebound and pupil responses are due to a prolonged period of sensory evidence accumulation, and that their correlated temporal dynamics support a shared neural mechanism underlying both pupil and microsaccade responses.
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spelling doaj-art-203576cbb9854411a647ef130d1f73942025-08-20T03:03:27ZengNature PortfolioScientific Reports2045-23222025-07-0115111610.1038/s41598-025-04748-0Eyes on hold: motion task difficulty jointly delays microsaccade and pupil responsesRania Ezzo0Bogeng Song1Bas Rokers2Marisa Carrasco3Department of Psychology, New York UniversityDepartment of Psychology, New York UniversityDepartment of Psychology, New York UniversityDepartment of Psychology, New York UniversityAbstract Microsaccades and pupil dynamics exhibit canonical temporal profiles, providing insights into perceptual and cognitive processes. Microsaccades are typically suppressed with respect to expected stimulus onset and followed by a rebound to baseline rates. Here, we investigated whether and how the temporal dynamics of microsaccades and pupil dilation vary with task difficulty for a motion perception task. We hypothesized that difficulty jointly delays the rebound of microsaccade rates and the time of peak pupil dilation when discriminating motion direction. Human observers discriminated motion direction (clockwise or counterclockwise) in a briefly presented perifoveal drifting stimulus, which varied according to two ‘easy’ vs ‘hard’ difficulty manipulations –cardinal vs oblique motion directions, and large vs small tilt offsets from the discriminated direction. We found that (1) increased task difficulty strengthened and prolonged microsaccade inhibition resulting in delayed rebounds, (2) peak pupillary responses were both larger in amplitude and delayed for more difficult conditions, (3) discrimination response time correlated with microsaccade rebounds and peak pupillary responses. We conclude that the delays in these microsaccade rebound and pupil responses are due to a prolonged period of sensory evidence accumulation, and that their correlated temporal dynamics support a shared neural mechanism underlying both pupil and microsaccade responses.https://doi.org/10.1038/s41598-025-04748-0MicrosaccadesPupilTask difficultyMotion discriminationOculomotor inhibition
spellingShingle Rania Ezzo
Bogeng Song
Bas Rokers
Marisa Carrasco
Eyes on hold: motion task difficulty jointly delays microsaccade and pupil responses
Scientific Reports
Microsaccades
Pupil
Task difficulty
Motion discrimination
Oculomotor inhibition
title Eyes on hold: motion task difficulty jointly delays microsaccade and pupil responses
title_full Eyes on hold: motion task difficulty jointly delays microsaccade and pupil responses
title_fullStr Eyes on hold: motion task difficulty jointly delays microsaccade and pupil responses
title_full_unstemmed Eyes on hold: motion task difficulty jointly delays microsaccade and pupil responses
title_short Eyes on hold: motion task difficulty jointly delays microsaccade and pupil responses
title_sort eyes on hold motion task difficulty jointly delays microsaccade and pupil responses
topic Microsaccades
Pupil
Task difficulty
Motion discrimination
Oculomotor inhibition
url https://doi.org/10.1038/s41598-025-04748-0
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AT basrokers eyesonholdmotiontaskdifficultyjointlydelaysmicrosaccadeandpupilresponses
AT marisacarrasco eyesonholdmotiontaskdifficultyjointlydelaysmicrosaccadeandpupilresponses