Sunday, March 27, 2011

Frontiers in Cognition - The Perspective Matters! (On Integrating the Body into the Self)

Here is a cool and geeky research paper from Frontiers in Cognition. In this article they are looking at the process of how we integrate the body as a part of the self. In integral theory, this is the stage that used to be (still is?) known in Wilberese as the Centaur stage - the integration of body and mind.

For this to be useful, the premise must be that we live most of lives as a "head." When asked where they experience their "self" to be, most people identify an area slightly above and behind the eyes. So the premise, at least in part, is valid.

This article explains how the framing of perspective allows integration to occur.

The perspective matters! Multisensory integration in ego-centric reference frames determines full-body ownership

Valeria I. Petkova*, Mehrnoush Khoshnevis and H. Henrik Ehrsson
  • Brain, Body and Self Laboratory, Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden

Recent advances in experimental science have made it possible to investigate the perceptual processes involved in generating a sense of owning an entire body. This is achieved by full-body ownership illusions which make use of specific patterns of visual and somatic stimuli integration. Here we investigate the fundamental question of the reference frames used in the process of attributing an entire body to the self. We quantified the strength of the body-swap illusion in conditions where the participants were observing this artificial body from the perspective of the first or third person. Consistent results from subjective reports and physiological recordings show that the first person visual perspective is critical for the induction of this full-body ownership illusion. This demonstrates that the multisensory integration processes producing the sense of corporeal self operates in an ego-centric reference frame.


Petkova VI, Khoshnevis M and Ehrsson HH. (2011, March 7). The perspective matters! Multisensory integration in ego-centric reference frames determines full-body ownership. Front. Psychology 2:35. doi: 10.3389/fpsyg.2011.00035

Here the introduction to offer a clearer idea of what the authors are looking at and what they seek to show.


How do we come to experience our body as part of ourselves? Does the mind have the capacity to attribute an entire new body to the self? These questions are fundamental to our understanding of the relationship between the body, the mind, and the sense of self (James, 1890; Gallagher, 2000; Metzinger, 2003; Merleau-Ponty, 2005).

Recent advances in experimental science have made it possible for cognitive neuroscientists to address this important aspect of self-awareness in controlled laboratory settings (Botvinick and Cohen, 1998; Jeannerod, 2003; Ehrsson et al., 2004; Makin et al., 2008; Blanke and Metzinger, 2009; Petkova and Ehrsson, 2010). One particularly powerful approach is the use of “full-body illusions” in which healthy individuals experience a new artificial body as their own (Ehrsson, 2007; Lenggenhager et al., 2007; Petkova and Ehrsson, 2008; Slater et al., 2009). This approach follows a long tradition in psychology and neuroscience of studying perceptual illusions to learn more about the basic processes that underlie normal perception. In one such full-body illusion, the “body-swap illusion” (Petkova and Ehrsson, 2008), the participants are able to sense the touches applied to the body of a shop mannequin and experience this body as their own. This illusion is elicited in the following way: the participants observe the artificial body via head-mounted displays (HMD) connected to video-cameras placed on the mannequin’s head. The cameras are positioned so that they look down at the mannequin’s body, and thus, the participants see the mannequin’s body at the location where they would normally see their own body. The illusion is evoked when the experimenter applies identical synchronous touches to the body of the mannequin and the participant’s body. The illusion is abolished, or significantly reduced, if the human body is replaced with an object that does not have a humanoid shape (e.g., a block of wood) or if asynchronous touches are applied to the two bodies (Petkova and Ehrsson, 2008). This findings suggest at the core of this perceptual phenomenon is the integration of multiple sources of sensory information centered on the spatial location of the “new” body (Petkova and Ehrsson, 2008).

Still unanswered, however, is the important question of the role played by the visual perspective in the process of perceiving an entire body as one’s own. In spatial cognition research, a basic distinction is made between the first person perspective (1PP) and the third person perspective (3PP; Vogeley and Fink, 2003), related to ego-centric and allocentric reference frames, respectively (Klatzky, 1998; Burgess, 2006). An ego-centric reference frame is a coordinate system centered on the body, and is considered to be important for functions related to perception and to performing actions (Fogassi et al., 1992; Graziano and Gross, 1998). In contrast, the allocentric reference frame corresponds to world coordinates centered on a reference point in extrapersonal space. This coordinate system is considered important for spatial cognitive functions such as determining one’s location with respect to environmental landmarks, spatial navigation, and spatial memory (Maguire et al., 1998; Burgess, 2006).

The uncertainty about the role played by the visual perspective in feeling ownership of a body arises both from experimental results from full-body illusions in healthy individuals (see below) and from certain neurological conditions which suggest that the relation between self-awareness and the first person visual perspective is not straightforward. For example, in evoked or spontaneous cases of autoscopy, a form of out-of-body experience in which people perceive themselves as being outside their own body looking at it from an altered egocentric perspective, people still report that the body they observe is their own, thus, they demonstrate intact body self-attribution, despite the fact that they are viewing the body from a 3PP (Blanke et al., 2002, 2004; Blanke and Mohr, 2005).

More directly relevant for the question of how a normally functioning mind creates a multisensory experience of one’s own body, as is under consideration here, is the fact that two principally different experimental set-ups have been used to induce “full-body illusions” associated with changes in perceived body ownership in healthy participants (Lenggenhager et al., 2007; Petkova and Ehrsson, 2008). In these experiments, synchronous visual and tactile stimulation is always applied both to the artificial body in sight of the participant and the participant’s own body which is out of sight. However, the illusory “own” body is either viewed from a 3PP, as though looking at another individual a couple of meters in front of oneself (Lenggenhager et al., 2007, 2009; Aspell et al., 2009), or from a 1PP (Ehrsson, 2007; Petkova and Ehrsson, 2008; Slater et al., 2009, 2010), as though directly looking down at one’s body. Logically, if the visual perspective is irrelevant, one would anticipate that the body ownership illusion would be evoked equally well in these two situations. Hence, some authors have concluded that body ownership would depend solely on the detection of visuo-tactile synchrony (Meyer et al., 2008).

Here, we sought to address this important question and to investigate which of the two basic visual perspectives is most important for the perceptual illusion of owning an entire artificial body and, therefore, for the general mechanisms of attributing a body to oneself. In two different behavioral set-ups, we directly compared experimental conditions in which the participants observed a body of a mannequin from either the first or the third person visual perspective. We hypothesized that the first person visual perspective would represent a fundamental constraint on the full-body illusion. This would be in line with the proposed model that the sense of body ownership relies on multisensory integration mechanisms operating in body-part-centered reference frames (Ehrsson et al., 2004; Makin et al., 2008; Petkova and Ehrsson, 2008; Ehrsson, 2011).

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