Weight illusions explained by efficient coding based on correlated natural statistics

Abstract In our everyday experience, the sizes and weights of objects we encounter are strongly correlated. When objects are lifted, visual information about size can be combined with haptic feedback about weight, and a naive application of Bayes’ rule predicts that the perceived weight of larger ob...

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Main Author: Paul M. Bays
Format: Article
Language:English
Published: Nature Portfolio 2024-12-01
Series:Communications Psychology
Online Access:https://doi.org/10.1038/s44271-024-00173-7
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author Paul M. Bays
author_facet Paul M. Bays
author_sort Paul M. Bays
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description Abstract In our everyday experience, the sizes and weights of objects we encounter are strongly correlated. When objects are lifted, visual information about size can be combined with haptic feedback about weight, and a naive application of Bayes’ rule predicts that the perceived weight of larger objects should be exaggerated and smaller objects underestimated. Instead, it is the smaller of two objects of equal weight that is perceived as heavier, a phenomenon termed the Size-Weight Illusion (SWI). Here we provide a normative explanation of the SWI based on principles of efficient coding, which dictate that stimulus properties should be encoded with a fidelity that depends on how frequently those properties are encountered in the environment. We show that the precision with which human observers estimate object weight varies as a function of both mass and volume in a manner consistent with the estimated joint distribution of those properties among everyday objects. We further show that participants’ seemingly “anti-Bayesian” biases (the SWI) are quantitatively predicted by Bayesian estimation when taking into account the gradient of discriminability induced by efficient encoding. The related Material-Weight Illusion (MWI) can also be accounted for on these principles, with surface material providing a visual cue that changes expectations about object density. The efficient coding model is further compatible with a wide range of previous observations, including the adaptability of weight illusions and properties of “non-illusory” objects. The framework is general and predicts perceptual biases and variability in any sensory properties that are correlated in the natural environment.
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spelling doaj-art-db7b816d076b4e9998ced994fc03df182025-08-20T02:31:41ZengNature PortfolioCommunications Psychology2731-91212024-12-01211910.1038/s44271-024-00173-7Weight illusions explained by efficient coding based on correlated natural statisticsPaul M. Bays0University of Cambridge, Department of PsychologyAbstract In our everyday experience, the sizes and weights of objects we encounter are strongly correlated. When objects are lifted, visual information about size can be combined with haptic feedback about weight, and a naive application of Bayes’ rule predicts that the perceived weight of larger objects should be exaggerated and smaller objects underestimated. Instead, it is the smaller of two objects of equal weight that is perceived as heavier, a phenomenon termed the Size-Weight Illusion (SWI). Here we provide a normative explanation of the SWI based on principles of efficient coding, which dictate that stimulus properties should be encoded with a fidelity that depends on how frequently those properties are encountered in the environment. We show that the precision with which human observers estimate object weight varies as a function of both mass and volume in a manner consistent with the estimated joint distribution of those properties among everyday objects. We further show that participants’ seemingly “anti-Bayesian” biases (the SWI) are quantitatively predicted by Bayesian estimation when taking into account the gradient of discriminability induced by efficient encoding. The related Material-Weight Illusion (MWI) can also be accounted for on these principles, with surface material providing a visual cue that changes expectations about object density. The efficient coding model is further compatible with a wide range of previous observations, including the adaptability of weight illusions and properties of “non-illusory” objects. The framework is general and predicts perceptual biases and variability in any sensory properties that are correlated in the natural environment.https://doi.org/10.1038/s44271-024-00173-7
spellingShingle Paul M. Bays
Weight illusions explained by efficient coding based on correlated natural statistics
Communications Psychology
title Weight illusions explained by efficient coding based on correlated natural statistics
title_full Weight illusions explained by efficient coding based on correlated natural statistics
title_fullStr Weight illusions explained by efficient coding based on correlated natural statistics
title_full_unstemmed Weight illusions explained by efficient coding based on correlated natural statistics
title_short Weight illusions explained by efficient coding based on correlated natural statistics
title_sort weight illusions explained by efficient coding based on correlated natural statistics
url https://doi.org/10.1038/s44271-024-00173-7
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