Visuospatial viewpoint manipulation during full-body illusion modulates subjective first-person perspective

Self-consciousness is based on multisensory signals from the body. In full-body illusion (FBI) experiments, multisensory conflict was used to induce changes in three key aspects of bodily self-consciousness (BSC): self-identification (which body 'I' identify with), self-location (where 'I' am located), and first-person perspective (from where 'I' experience the world; 1PP). Here, we adapted a previous FBI protocol in which visuotactile stroking was administered by a robotic device (tactile stroking) and simultaneously rendered on the back of a virtual body (visual stroking) that participants viewed on a head-mounted display as if filmed from a posterior viewpoint of a camera. We compared the effects of two different visuospatial viewpoints on the FBI and thereby on these key aspects of BSC. During control manipulations, participants saw a no-body object instead of a virtual body (first experiment) or received asynchronous versus synchronous visuotactile stroking (second experiment). Results showed that within-subjects visuospatial viewpoint manipulations affected the subjective 1PP ratings if a virtual body was seen but had no effect for viewing a non-body object. However, visuospatial viewpoint had no effect on self-identification, but depended on the viewed object and visuotactile synchrony. Self-location depended on visuospatial viewpoint (first experiment) and visuotactile synchrony (second experiment). Our results show that the visuospatial viewpoint from which the virtual body is seen during FBIs modulates the subjective 1PP and that such viewpoint manipulations contribute to spatial aspects of BSC. We compare the present data with recent data revealing vestibular contributions to the subjective 1PP and discuss the multisensory nature of BSC and the subjective 1PP.

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

Olaf Blanke, Julio Duenas, Christophe Lopez, Roberto Martuzzi, Christian Pfeiffer, Valentin Marc Schmutz

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.

Public Library of Science2013

Neuroscience of Bodily Self-Consciousness

Olaf Blanke, Estelle Palluel, Christian Pfeiffer

We review recent research about human subjectivity and self-consciousness that has focused on cognitive psychology and neuroimaging of bodily self-consciousness. Multidisciplinary research on the fields of neurology, cognitive neuroscience and virtual reality opens new avenues to investigate brain mechanisms underlying a fundamental sense of the bodily self. Clinical evidence for the implication of right temporo-parietal junction for bodily self-consciousness has received support by studies in which virtual-reality based own body illusions are evoked in healthy participants to study the underlying processes. A series of experiments will be reviewed in which it was shown that the experiences of self-location, self-identification and the first-person perspective can be manipulated experimentally and rely on the integration of multisensory stimuli (touch, vision, proprioception, vestibular information). Specific protocols are available to predictably influence the different aspects of bodily self consciousness. We predict that the understanding of fundamental brain mechanisms of bodily self-consciousness will lead to unprecedented empirical insights that are of broad relevance for science, virtual reality, engineering, the humanities, as well as medicine and psychotherapy.

2011

Interoception and Empathy Impact Perspective Taking

Jane Aspell, Olaf Blanke, Bruno Herbelin, Lukas Heydrich

Adopting the perspective of another person is an important aspect of social cognition and has been shown to depend on multisensory signals from one's own body. Recent work suggests that interoceptive signals not only contribute to own-body perception and self-consciousness, but also to empathy. Here we investigated if social cognition - in particular adopting the perspective of another person - can be altered by a systematic manipulation of interoceptive cues and further, if this effect depends on empathic ability. The own-body transformation task (OBT) - wherein participants are instructed to imagine taking the perspective and position of a virtual body presented on a computer screen - offers an effective way to measure reaction time differences linked to the mental effort of taking an other's perspective. Here, we adapted the OBT with the flashing of a silhouette surrounding the virtual body, either synchronously or asynchronously with the timing of participants' heartbeats. We evaluated the impact of this cardio-visual synchrony on reaction times and accuracy rates in the OBT. Empathy was assessed with the empathy quotient (EQ) questionnaire. Based on previous work using the cardio-visual paradigm, we predicted that synchronous (vs. asynchronous) cardio-visual stimulation would increase self-identification with the virtual body and facilitate participants' ability to adopt the virtual body's perspective, thereby enhancing performance on the task, particularly in participants with higher empathy scores. We report that participants with high empathy showed significantly better performance during the OBT task during synchronous versus asynchronous cardio-visual stimulation. Moreover, we found a significant positive correlation between empathic ability and the synchrony effect (the difference in reaction times between the asynchronous and synchronous conditions). We conclude that synchronous cardio-visual stimulation between the participant's body and a virtual body during an OBT task makes it easier to adopt the virtual body's perspective, presumably based on multisensory integration processes. However, this effect depended on empathic ability, suggesting that empathy, interoception and social perspective taking are inherently linked.

2021

Interoception and Empathy Impact Perspective Taking

Jane Aspell, Olaf Blanke, Bruno Herbelin, Lukas Heydrich

2021