Distortions of perceived volume and length of body parts

Sadibolova, Renata; Ferre`, Elisa R.; Linkenauger, Sally A. and Longo, Matthew R.. 2019. Distortions of perceived volume and length of body parts. Cortex, 111, pp. 74-86. ISSN 0010-9452 [Article]

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Abstract or Description

We experience our body as a 3D, volumetric object in the world. Measures of our conscious body image, in contrast, have investigated the perception of body size along one or two dimensions at a time. There is, thus, a discrepancy between existing methods for measuring body image and our subjective experience of having 3D body. Here we assessed in a sample of healthy adults the perception of body size in terms of its 1D length and 3D volume. Participants were randomly assigned to two groups using different measuring units (other body part and non-body object). They estimated how many units would fit in a perceived size of body segments and the whole body. The patterns of length and volume misperception across judged segments were determined as their perceived size proportional to their actual size. The pattern of volume misperception paints the representation of 3D body proportions resembling those of a somatosensory homunculus. The body parts with a smaller actual surface area relative to their volume were underestimated more. There was a tendency for body parts underestimated in volume to be overestimated in length. Perceived body proportions thus changed as a function of judgement type while showing a similarity in magnitude of the absolute estimation error, be it an underestimation of volume or overestimation of length. The main contribution of this study is assessing the body image as a 3D body representation, and thus extending beyond the conventional ‘allocentric’ focus to include the body on the inside. Our findings highlight the value of studying the perceptual distortions “at the baseline”, i.e., in healthy population, so as to advance the understanding of the nature of perceptual distortions in clinical conditions.

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Additional Information:

This research was supported by a doctoral studentship from the Economic and Social Research Council, U.K. (ES/J500021/1), and the Welcome Trust/Birkbeck University ISSF funding (204770/Z/16/Z) to RS, and the European Research Council Grant ERC-2013-StG-336050 under the FP7 to MRL.


Body image, 3D body, Body size perception, Body proportions, Surface area to volume ratio

Departments, Centres and Research Units:

Psychology > Timing, Awareness, and Suggestion Lab


13 October 2018Accepted
1 November 2018Published Online
1 February 2019Published

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Date Deposited:

26 Nov 2018 11:46

Last Modified:

01 Nov 2019 02:26

Peer Reviewed:

Yes, this version has been peer-reviewed.



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