Multisensory Origin of the Subjective First-Person Perspective: Visual, Tactile, and Vestibular Mechanisms

Christian Pfeiffer,Julio Angel Duenas,Christophe Lopez,Valentin Schmutz,Roberto Martuzzi,Olaf Blanke,Manos Tsakiris

doi:10.1371/journal.pone.0061751

Abstract

In three experiments we investigated the effects of visuo-tactile and visuo-vestibular conflict about the direction of gravity on three aspects of bodily self-consciousness: self-identification, self-location, and the experienced direction of the first-person perspective. Robotic visuo-tactile stimulation was administered to 78 participants in three experiments. Additionally, we presented participants with a virtual body as seen from an elevated and downward-directed perspective while they were lying supine and were therefore receiving vestibular and postural cues about an upward-directed perspective. Under these conditions, we studied the effects of different degrees of visuo-vestibular conflict, repeated measurements during illusion induction, and the relationship to a classical measure of visuo-vestibular integration. Extending earlier findings on experimentally induced changes in bodily self-consciousness, we show that self-identification does not depend on the experienced direction of the first-person perspective, whereas self-location does. Changes in bodily self-consciousness depend on visual gravitational signals. Individual differences in the experienced direction of first-person perspective correlated with individual differences in visuo-vestibular integration. Our data reveal important contributions of visuo-vestibular gravitational cues to bodily self-consciousness. In particular we show that the experienced direction of the first-person perspective depends on the integration of visual, vestibular, and tactile signals, as well as on individual differences in idiosyncratic visuo-vestibular strategies.

Highlights

IntroductionRecent research investigated how the processing of bodily signals modulates bodily self-consciousness and in particular selflocation (i.e. the experience of where ‘I’ am in space) and selfidentification with the body (i.e. the experience of identifying and owning a body) [1,2,3,4,5]
Recent research investigated how the processing of bodily signals modulates bodily self-consciousness and in particular selflocation and selfidentification with the body [1,2,3,4,5]
In Experiment 2, we investigated whether individual differences in the experienced direction of the first-person perspective that we observed in Experiment 1 for strong visuo-vestibular conflicts could be quantified in repeated judgments of first-person perspective

Summary

Introduction

Recent research investigated how the processing of bodily signals modulates bodily self-consciousness and in particular selflocation (i.e. the experience of where ‘I’ am in space) and selfidentification with the body (i.e. the experience of identifying and owning a body) [1,2,3,4,5] In these studies participants were presented with conflicting multisensory stimuli (such as visual, tactile, and proprioceptive signals) about the location and appearance of a body part (e.g. rubber hand illusion: [2]; enfacement illusion: [6,7]) or their entire body (e.g. full-body illusion: [8,9]). These studies are important for cognitive mechanisms of perspective taking and highlight the effects of different visuo-spatial viewpoints on the strength of self-identification, they do not allow to induce changes in more subjective aspects of first-person perspective, that is the experience from where ‘I’ perceive the world [10,11]

Methods

Results

Conclusion