Psychophysical evidence for an internal model of gravity in the visual and vestibular estimates of vertical motion duration

Abstract The motion of objects and ourselves along the vertical is affected by gravitational acceleration. However, the visual system is poorly sensitive to accelerations, and the otolith organs do not disassociate gravitational and inertial accelerations. Here, we tested the hypothesis that the bra...

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Main Authors: Sergio Delle Monache, Barbara La Scaleia, Anna Finazzi Agrò, Francesco Lacquaniti, Myrka Zago
Format: Article
Language:English
Published: Nature Portfolio 2025-03-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-94512-1
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author Sergio Delle Monache
Barbara La Scaleia
Anna Finazzi Agrò
Francesco Lacquaniti
Myrka Zago
author_facet Sergio Delle Monache
Barbara La Scaleia
Anna Finazzi Agrò
Francesco Lacquaniti
Myrka Zago
author_sort Sergio Delle Monache
collection DOAJ
description Abstract The motion of objects and ourselves along the vertical is affected by gravitational acceleration. However, the visual system is poorly sensitive to accelerations, and the otolith organs do not disassociate gravitational and inertial accelerations. Here, we tested the hypothesis that the brain estimates the duration of vertical visual motion and self-motion by means of an internal model of gravity predicting that downward motions are accelerated and upward motions are decelerated by gravity. In visual sessions, a target moved up or down while participants remained stationary. In vestibular sessions, participants were moved up or down in the absence of a visual target. In visual-vestibular sessions, participants were moved up or down while the visual target remained fixed in space. In all sessions, we verified that participants looked straight-ahead. We found that downward motions of either the visual target or the participant were systematically perceived as lasting less than upward motions of the same duration, and vice-versa for the opposite direction of motion, consistent with the predictions of the internal model of gravity. In visual-vestibular sessions, there was no significant difference in the average estimates of duration of downward and upward motion of the participant. However, there was large inter-subject variability of these estimates.
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spelling doaj-art-9778a11b25ab4323b31a5bcef8057bb22025-08-20T02:10:12ZengNature PortfolioScientific Reports2045-23222025-03-0115111510.1038/s41598-025-94512-1Psychophysical evidence for an internal model of gravity in the visual and vestibular estimates of vertical motion durationSergio Delle Monache0Barbara La Scaleia1Anna Finazzi Agrò2Francesco Lacquaniti3Myrka Zago4Laboratory of Neuromotor Physiology, IRCCS Santa Lucia FoundationLaboratory of Neuromotor Physiology, IRCCS Santa Lucia FoundationLaboratory of Neuromotor Physiology, IRCCS Santa Lucia FoundationLaboratory of Neuromotor Physiology, IRCCS Santa Lucia FoundationLaboratory of Neuromotor Physiology, IRCCS Santa Lucia FoundationAbstract The motion of objects and ourselves along the vertical is affected by gravitational acceleration. However, the visual system is poorly sensitive to accelerations, and the otolith organs do not disassociate gravitational and inertial accelerations. Here, we tested the hypothesis that the brain estimates the duration of vertical visual motion and self-motion by means of an internal model of gravity predicting that downward motions are accelerated and upward motions are decelerated by gravity. In visual sessions, a target moved up or down while participants remained stationary. In vestibular sessions, participants were moved up or down in the absence of a visual target. In visual-vestibular sessions, participants were moved up or down while the visual target remained fixed in space. In all sessions, we verified that participants looked straight-ahead. We found that downward motions of either the visual target or the participant were systematically perceived as lasting less than upward motions of the same duration, and vice-versa for the opposite direction of motion, consistent with the predictions of the internal model of gravity. In visual-vestibular sessions, there was no significant difference in the average estimates of duration of downward and upward motion of the participant. However, there was large inter-subject variability of these estimates.https://doi.org/10.1038/s41598-025-94512-1Internal modelGravityOtolithsPsychophysicsBiasHuman
spellingShingle Sergio Delle Monache
Barbara La Scaleia
Anna Finazzi Agrò
Francesco Lacquaniti
Myrka Zago
Psychophysical evidence for an internal model of gravity in the visual and vestibular estimates of vertical motion duration
Scientific Reports
Internal model
Gravity
Otoliths
Psychophysics
Bias
Human
title Psychophysical evidence for an internal model of gravity in the visual and vestibular estimates of vertical motion duration
title_full Psychophysical evidence for an internal model of gravity in the visual and vestibular estimates of vertical motion duration
title_fullStr Psychophysical evidence for an internal model of gravity in the visual and vestibular estimates of vertical motion duration
title_full_unstemmed Psychophysical evidence for an internal model of gravity in the visual and vestibular estimates of vertical motion duration
title_short Psychophysical evidence for an internal model of gravity in the visual and vestibular estimates of vertical motion duration
title_sort psychophysical evidence for an internal model of gravity in the visual and vestibular estimates of vertical motion duration
topic Internal model
Gravity
Otoliths
Psychophysics
Bias
Human
url https://doi.org/10.1038/s41598-025-94512-1
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