Illusion Of Virtual Body Ownership Research Articles

Electroencephalographic evidence for the involvement of mirror-neuron and error-monitoring related processes in virtual body ownership

The illusion that an artificial or virtual object becomes part of one’s body has been demonstrated and productively investigated in the past two decades. Empirical and theoretical accounts of this phenomenon suggest that the body ownership illusion relies not on a single process, but rather on the alignment of the biological and the alternative bodies across multiple aspects. However, the portrayal of these aspects and the demarcation of their neurophysiological correlates has yet to be established.Our study examines electroencephalographic (EEG) markers of two extensively studied systems in the context of virtual body ownership illusion: the mirror-neuron system (MNS) and the error-monitoring system (EMS). We designed an experimental manipulation of brief involuntary and unexpected virtual hand bounces, which triggers both systems, and examined how the response of EEG markers of these systems to this manipulation is modulated by three aspects of body ownership: agency, visuotactile synchronicity, and semantic congruence between the participant’s hands and its virtual representation.We found evidence for enhanced MNS-related power suppression at the Mu band in the synchronous and semantic congruence conditions. On the other hand, the EMS-related Pe/P300 wave was reduced by semantic congruence. This Pe/P300 effect was stronger among participants who exhibited higher acceptance of the spatial illusion and an increased tendency for affective empathy. Mu power and Pe/P300 were not correlated, suggesting a dissociation between the distinct aspects of body ownership they probe. The findings suggest that synchronicity and semantic congruence induce sensorimotor sensitivity to the alternative body, whereas the latter parameter also buffers minor erroneous virtual motions. These neurophysiological markers may be added to the arsenal of body ownership probes and incorporated into VR rehabilitation protocols.

Measuring the Effects through Time of the Influence of Visuomotor and Visuotactile Synchronous Stimulation on a Virtual Body Ownership Illusion

Previous studies have examined the experience of owning a virtual surrogate body or body part through specific combinations of cross-modal multisensory stimulation. Both visuomotor (VM) and visuotactile (VT) synchronous stimulation have been shown to be important for inducing a body ownership illusion, each tested separately or both in combination. In this study we compared the relative importance of these two cross-modal correlations, when both are provided in the same immersive virtual reality setup and the same experiment. We systematically manipulated VT and VM contingencies in order to assess their relative role and mutual interaction. Moreover, we present a new method for measuring the induced body ownership illusion through time, by recording reports of breaks in the illusion of ownership ('breaks') throughout the experimental phase. The balance of the evidence, from both questionnaires and analysis of the breaks, suggests that while VM synchronous stimulation contributes the greatest to the attainment of the illusion, a disruption of either (through asynchronous stimulation) contributes equally to the probability of a break in the illusion.

Supplementary Material for: “Measuring the Effects through Time of the Influence of Visuomotor and Visuotactile Synchronous Stimulation on a Virtual Body Ownership Illusion”

<i>Supplementary Material for:</i> “Measuring the Effects through Time of the Influence of Visuomotor and Visuotactile Synchronous Stimulation on a Virtual Body Ownership Illusion”

The Effects of Rotating the Self Out of the Body in the Full Virtual Body Ownership Illusion

It has been shown that it is possible to induce a strong illusion that a virtual body (VB) is one's own body. However, the relative influence of a first-person-perspective (1PP) view of the VB and spatial coincidence of the real body and VB remains unclear. We demonstrate a method that permits separation of these two factors. It provides a 1PP view of a VB, supporting visuomotor synchrony between real body and VB movements, but where the entire scene including the body is rotated 15 degrees upwards through the axis connecting the eyes, so that the VB and real body are coincident only through this axis. In a within-subjects study that compared this 15 degrees rotation with a 0 degrees rotation condition, participants reported only slightly diminished levels of perceived ownership of the VB in the rotated condition and did not detect the rotation of the scene. These results indicate that strong spatial coincidence of the virtual and real bodies is not necessary for a full-body ownership illusion. The rotation method used, similar to the effects of vertical prisms, did not produce significant negative side-effects, thus providing a useful methodology for further investigations of body ownership.