Keeping in touch with one's self: multisensory mechanisms of self-consciousness.

Jane E Aspell,Bigna Lenggenhager,Olaf Blanke,Mark A Williams

doi:10.1371/journal.pone.0006488

Jane E Aspell, Bigna Lenggenhager + Show 2 more

Open Access

https://doi.org/10.1371/journal.pone.0006488

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Abstract

BackgroundThe spatial unity between self and body can be disrupted by employing conflicting visual-somatosensory bodily input, thereby bringing neurological observations on bodily self-consciousness under scientific scrutiny. Here we designed a novel paradigm linking the study of bodily self-consciousness to the spatial representation of visuo-tactile stimuli by measuring crossmodal congruency effects (CCEs) for the full body.Methodology/Principal FindingsWe measured full body CCEs by attaching four vibrator-light pairs to the trunks (backs) of subjects who viewed their bodies from behind via a camera and a head mounted display (HMD). Subjects made speeded elevation (up/down) judgments of the tactile stimuli while ignoring light stimuli. To modulate self-identification for the seen body subjects were stroked on their backs with a stick and the felt stroking was either synchronous or asynchronous with the stroking that could be seen via the HMD.We found that (1) tactile stimuli were mislocalized towards the seen body (2) CCEs were modulated systematically during visual-somatosensory conflict when subjects viewed their body but not when they viewed a body-sized object, i.e. CCEs were larger during synchronous than during asynchronous stroking of the body and (3) these changes in the mapping of tactile stimuli were induced in the same experimental condition in which predictable changes in bodily self-consciousness occurred.Conclusions/SignificanceThese data reveal that systematic alterations in the mapping of tactile stimuli occur in a full body illusion and thus establish CCE magnitude as an online performance proxy for subjective changes in global bodily self-consciousness.

Highlights

The most basic foundations of the self arguably lie in those complex brain systems that represent the body [1,2,3,4,5]
In the body visible condition the congruency effects (CCEs) was larger when the light appeared on the same side as the tactile stimulus, compared to when it appeared on the different side
There was During the experiment there were times when: 1 It seemed as if I was feeling the touch of the stick in the location where I saw the virtual body being touched 2 It seemed as though the touch I felt was caused by the stick touching the virtual body

Summary

Introduction

The most basic foundations of the self arguably lie in those complex brain systems that represent the body [1,2,3,4,5]. Study 2 revealed that the CCE differs between synchronous and asynchronous stroking, and study 1 showed that CCEs are found when the LEDs are presented on a body but not when the body is not visible.

Results

Conclusion