Size constancy affects the perception and parietal neural representation of object size

Kristensen, S., Fracasso, A. , Dumoulin, S. O., Almeida, J. and Harvey, B. M. (2021) Size constancy affects the perception and parietal neural representation of object size. NeuroImage, 232, 117909. (doi: 10.1016/j.neuroimage.2021.117909) (PMID:33652148)

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Humans and animals rely on accurate object size perception to guide behavior. Object size is judged from visual input, but the relationship between an object's retinal size and its real-world size varies with distance. Humans perceive object sizes to be relatively constant when retinal size changes. Such size constancy compensates for the variable relationship between retinal size and real-world size, using the context of recent retinal sizes of the same object to bias perception towards its likely real-world size. We therefore hypothesized that object size perception may be affected by the range of recently viewed object sizes, attracting perceived object sizes towards recently viewed sizes. We demonstrate two systematic biases: a central tendency attracting perceived size towards the average size across all trials, and a serial dependence attracting perceived size towards the size presented on the previous trial. We recently described topographic object size maps in the human parietal cortex. We therefore hypothesized that neural representations of object size here would be attracted towards recently viewed sizes. We used ultra-high-field (7T) functional MRI and population receptive field modeling to compare object size representations measured with small (0.05-1.4°diameter) and large objects sizes (0.1-2.8°). We found that parietal object size preferences and tuning widths follow this presented range, but change less than presented object sizes. Therefore, perception and neural representation of object size are attracted towards recently viewed sizes. This context-dependent object size representation reveals effects on neural response preferences that may underlie context dependence of object size perception.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Fracasso, Dr Alessio
Authors: Kristensen, S., Fracasso, A., Dumoulin, S. O., Almeida, J., and Harvey, B. M.
College/School:College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience
Journal Name:NeuroImage
ISSN (Online):1095-9572
Published Online:27 February 2021
Copyright Holders:Copyright © 2021 The Authors
First Published:First published in NeuroImage 232: 117909
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
303685Stable perception of external stimuli over time: oculo-motor and visual processing mechanismsAlessio FracassoBiotechnology and Biological Sciences Research Council (BBSRC)BB/S006605/1NP - Centre for Cognitive Neuroimaging (CCNi)