The perceived size of the implicit representation of the dorsum and palm of the hand.

Sarah D’Amour,Laurence R Harris,Gavin Buckingham

doi:10.1371/journal.pone.0230624

Abstract

The perception of the body and its parts has traditionally been studied using the conscious body image. Here, we determine the implicit representation of the hand. Participants were sequentially shown two life-size images of either the dorsal or palmar surface of their hand. In one interval either the horizontal or vertical dimension of the image was varied using an adaptive staircase, while the other interval contained the full-size, undistorted image. Participants reported which image most closely matched their hand. The staircase honed in on the distorted image that was equally likely to be judged as matching their own hand as the accurate image. The implicit representation was taken as midway between these two images. The experiment was repeated with different hand orientations. Perceived width depended on the orientation, with differences found between the upright and right orientations. Interestingly, the perceived length of the dorsum and palm were different from each other—length of the dorsum was overestimated whereas palm length was perceived accurately. This study reveals distortions of the implicit representation of the hands in healthy individuals.

Highlights

The hand has been the main focus for studying various aspects of perception and action such as touch, haptics, motor skills, reaching, grasping, pointing, tool use, position sense, size perception, etc. [1,2,3,4,5,6,7,8,9,10,11,12,13,14] and so it is important to get a complete picture of how the hand is represented in the brain
We recently developed a novel psychophysical method for determining perceived body size that provides an objective, unbiased, implicit measure of the body representation in the brain [15,16]
Data in only one out of 16 of the conditions were significantly correlated with Body Shape Questionnaire (BSQ) score so BSQ groups were not included in the analyses

Summary

Introduction

The hand has been the main focus for studying various aspects of perception and action such as touch, haptics, motor skills, reaching, grasping, pointing, tool use, position sense, size perception, etc. [1,2,3,4,5,6,7,8,9,10,11,12,13,14] and so it is important to get a complete picture of how the hand is represented in the brain. [1,2,3,4,5,6,7,8,9,10,11,12,13,14] and so it is important to get a complete picture of how the hand is represented in the brain. All these sensory processes and tasks require knowledge about how the brain represents the hand and can be impacted by any size or shape distortions that may occur. We examine the perceived size of the dorsum and palm of the hand t

Methods

Results

Discussion

Conclusion