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Virtual Reality Body Swapping:
A Tool for Modifying the Allocentric
Memory of the Body
Silvia Serino, PhD,
1
Elisa Pedroli, PsyD,
1
Anouk Keizer, PhD,
2
Stefano Triberti, MA,
3
Antonios Dakanalis, PhD,
4,5
Federica Pallavicini, PhD,
1,6
Alice Chirico, MA,
1
and Giuseppe Riva, PhD
1,3
Abstract
An increasing amount of evidence has shown that embodiment of a virtual body via visuo-tactile stimulation
can lead to an altered perception of body and object size. The current study aimed to investigate whether virtual
reality (VR) body swapping can be an effective tool for modifying the enduring memory of the body. The
experimental sample included 21 female participants who were asked to estimate the width and circumference
of different body parts before any kind of stimulation and after two types of body swapping illusions (‘‘syn-
chronous visuo-tactile stimulation’’ and ‘‘asynchronous visuo-tactile stimulation’’). Findings revealed that after
participants embodied a virtual body with a skinny belly (independently of the type of visuo-tactile stimulation),
there was an update of the stored representation of the body: participants reported a decrease in the ratio
between estimated and actual body measures for most of the body parts considered. Based on the Allocentric
Lock Theory, these findings provide first evidence that VR body swapping is able to induce a change in the
memory of the body. This knowledge may be potentially useful for patients suffering from eating and weight
disorders.
Introduction
R
ecently, Tessari et al. strongly emphasized the
centrality of the body for our conscious interactions with
the external world, specifically suggesting that: ‘‘The body,
as the subject or the object of our experience, mediates all the
interactions between our mind and the world . Like other
psychological phenomena, the experience of one’s body calls
for parallel biological, behavioural and first-person styles
of exploration.’’
1(p 643)
To perceive and control the body, it
is necessary to integrate information from multiple sen-
sory channels relating to several parts of the body. To this
end, somatosensory, visual, proprioceptive, vestibular, and
acoustic information are integrated into complex and multi-
sensory representations.
1
Blanke
2
defined the ‘‘bodily self-
consciousness’’ as a special aspect of self-consciousness
specifically derived from being ‘‘housed’’ in a body. It is
marked by three particular features: self-identification with a
body (i.e., the feeling of the body ownership), self-location
(i.e., the feeling of being in the space), and the first-person
perspective (i.e., the feeling of egocentrically perceiving the
world).
Recently, many interesting studies have used different
techniques to induce multisensory conflict to investigate
these aspects of bodily self-consciousness.
3–9
One of these
techniques is the well-known body swapping illusion, which
is a method to induce the illusory experience of owning a
virtual body.
8,10,11
This illusion can be evoked by observing,
from a first-person perspective, a virtual body being stroked
synchronously and/or asynchronously with the participants’
real body. This procedure offers the chance experimentally
to separate the self-location from the physical body, a con-
dition that is observable only in abnormal circumstances
(i.e., out-of-body experiences). Previous work has shown
that embodiment of a virtual body via visuo-tactile stimu-
lation can lead to altered perception of body and object size
(see, e.g., Kilteni et al.,
12
Normand et al.,
13
van der Hoort
et al.,
14
Piryankova et al.,
15
and Ehrsson et al.
16
). Indeed, in
1
Applied Technology for Neuro-Psychology Lab, IRCCS Istituto Auxologico Italiano, Milan, Italy.
2
Department of Experimental Psychology, Faculty of Social and Behavioral Sciences, Utrecht University, Utrecht, Netherlands.
3
Department of Psychology, Catholic University of the Sacred Heart, Milan, Italy.
4
Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy.
5
Department of Surgery and Interdisciplinary Medicine, University of Milano-Bicocca, Milan, Italy.
6
Centre for Studies in Communication Sciences—CESCOM, University of Milano-Bicocca, Milan, Italy.
CYBERPSYCHOLOGY,BEHAVIOR, AND SOCIAL NETWORKING
Volume 19, Number 2, 2016
ª Mary Ann Liebert, Inc.
DOI: 10.1089/cyber.2015.0229
127
order to locate oneself consciously outside one’s physical
body, it is necessary to achieve a translocation of the stored
first-person perspective from our physical experienced body
to another body, through an integration of multisensory
signals. This might affect our stored body representation. An
interesting example of this process was offered by Normand
et al.,
13
who specifically demonstrated the influence of body
swapping illusion on body representation. In their study,
male participants viewed from a first-person perspective a
virtual body with an inflated belly substituted for their own:
this experience, combined with synchronous visuo-tactile
stimulation, produced changes in their body representation
toward the larger belly size. Along the same lines, Preston
et al. demonstrated that illusory ownership over a slimmer
body promoted a significant decrease in participants’ per-
ceived body size and an increase in body satisfaction.
17
However, Piryankova et al.
15
did not find a specific effect of
synchronous visuo-tactile stimulation on the ‘‘experienced
body’’ (in their definition, ‘‘the body that the participant feels
she has at that moment’’) in terms of body size estimations.
Specifically, their findings indicated that changes in body
size experience occurred after visual experience with the
body, before visuo-tactile stimulation was provided.
A recent neuroscientific framework—the Allocentric
Lock Theory
18–21
—has emphasized the role of spatial rep-
resentations and their transformation in body representations,
which may influence the way the body is ‘‘experienced’’ and
‘‘remembered.’’ According to the literature, it is possible
to distinguish between two spatial representations that are
continuously interacting with each other: the egocentric and
allocentric representation. These were defined based on the
reference point used to encode and store information from the
surrounding world.
22–25
Egocentric representations code and
continuously update information in relation to the individual
(i.e., body as the reference point for first-person perspective
experience), while allocentric representations are responsi-
ble for the long-term storage of information independent
of the individual (i.e., environmental features as reference
points with the body as an object similar to the others objects
in the world). In particular, following the Allocentric Lock
Theory,
18–21
the egocentric representations, which are driven
by perceptual input, continuously update the contents of the
allocentric representation of the body. A recent clinical trial
involving obese women offered support for this theory, find-
ing that when virtual reality (VR) was used as an instrument
to induce change in negative bodily representations, the main-
tenance of treatment results was significantly better at 1 year
follow-up compared with the usual treatment (i.e., cognitive–
behavioral therapy).
26
Although not definitive, these results are
promising and give rise to interesting research questions. For
example, could VR body swapping be an effective tool for
modifying the memory of the body?
20,27
The current pilot study takes the first step in providing
an answer to this question. Using a VR set-up, female par-
ticipants viewed, from a first-person perspective, a virtual
body with a skinny belly substituted for their own physical
body (i.e., updated egocentric body) in two conditions (i.e.,
synchronous vs. asynchronous visuo-tactile stimulation).
Specifically, it was hypothesized that illusory ownership of
a virtual body resulted in changes in the remembered body
representation, as measured by asking participants to estimate
their body size.
Materials and Methods
Participants
Twenty-one female participants from the Catholic Uni-
versity of the Sacred Heart, Milan, Italy (M
age
= 22.76 years,
SD = 2.42 years; M
BMI
= 21.36, SD = 1.91) voluntarily took
part in the study. They were recruited through announce-
ments during lessons. See Supplementary Table S1 for
more details about study criteria and the clinical assessment
procedure.
Materials
The Virtual Belly Illusion.
A virtual body was developed
(standard for all participants). The body was shown with a
skinny belly (avatar waist circumference: 73.94 cm; mean
actual waist circumference in the sample: 85.70 cm, SD =
6.27 cm) and was standing upright in a stimulus-free room
(The Belly Illusion VR Software; see Fig. 1). As detailed
later in the procedure, all participants were asked to wear a
head-mounted display (HMD; Oculus Rift DK2) to visualize
the first-person perspective of the skinny belly of the virtual
body (1080p resolution).
The HMD was connected to a portable computer (HP
TRUE VISION with CPU Intel
Corei7). An extra-
infrared camera, positioned at the top of the portable com-
puter, was used to reduce the latency of the visualization in
the VR environment. During the illusion, participants were
touched on their actual belly. This touching was visually
mimicked on the belly of the virtual body using a motion
tracking device (Razer Hydra Portal 2 Bundle) that was
connected to the portable computer. Touching the actual belly
of participants was mimicked in VR either synchronously or
asynchronously, depending on the experimental condition.
To evaluate the efficacy of this procedure in inducing
an illusory feeling of ownership of the virtual body, an
adapted version of the embodiment questionnaire developed
by Piryankova et al.
15
was administered at the end of the
two virtual experiences (i.e., synchronous vs. asynchronous
visuo-tactile stimulation). The embodiment questionnaire is
a 15-item self-report questionnaire using a 7-point Likert
response scale. It evaluates how participants experience the
illusion at the level of ownership (i.e., ‘‘I felt as if the virtual
body was my body’’), self-location (i.e., ‘‘I felt as if I was
inside the virtual body’’), and agency (i.e., ‘‘I had the feeling
that I had control over the virtual body’’).
Body size estimation. Participants were asked to esti-
mate the width and circumference of three different parts of
their body: shoulders, abdomen, and hips. Moreover, they
were also asked to estimate their height. Each body part was
estimated separately and in counterbalanced order. Regard-
ing width estimations, participants were asked to stand in
front of a wooden blackboard and indicate the distance be-
tween the left and right side of a certain body part (e.g., the
distance between the left and right hip) using adhesive rub-
bers. Regarding circumference estimations, participants
were asked to estimate the circumference of the above-
mentioned three parts of their body by placing a piece of rope
in a circle/oval on the floor. Specifically, in this procedure
participants were required to retrieve a memory of their body
representation and to reproduce it within a third-person
128 SERINO ET AL.
perspective. Then, using the same procedure, participants
were also asked to estimate the height, width, and circum-
ference of the shoulders, abdomen, and hips of the virtual
body they had seen during the illusion to investigate whether
this procedure results in changes in transient egocentric
representations related to the body avatar. The experimenter
measured and wrote down all the body size estimations.
Actual body measures. The actual width and circumfer-
ence of the relevant body parts of the participants were mea-
sured at the beginning of the experiment using the Size Stream
3D Body Scanner. The Size Stream 3D Body Scanner is a full-
body, no-contact, 3D body measurement system using 14 in-
frared depth sensors positioned at six angles and seven dif-
ferent heights around the body to obtain full coverage in less
than 6 seconds (scan volume of 2 meters, 2.15 meters in height
by 0.95 meters in width by 0.8–1.2 meters in depth).
Procedure
Before starting the experimental procedure, each partici-
pant was provided with written information about the study
and was asked to sign an informed consent form to partici-
pate in the study. Subsequently, clinical standard tools were
administered to each participant (Mini International Neu-
ropsychiatric Interview—MINI,
28,29
and Eating Attitude
Test—EAT-26
30
) to exclude present and past psychiatric
illness, specifically eating disorder symptoms. Next, all
participants were asked to enter a private enclosure attached
to the Size Stream 3D Body Scanner and take off their outer
clothing in order to obtain the most accurate scan results. In
the scan area, footprints on the floor indicated where the
participants should stand, and there was a handle for them to
hold. The scan session lasted less than 6 seconds. Moreover,
all participants were weighed to ensure that they met the
study criteria (see Supplementary Table S1). Then, all par-
ticipants were asked to provide a first estimation of their
body size as explained previously. At the start of the ex-
perimental session, participants were required to wear the
HMD to complete the Virtual Belly Illusion. The experi-
menter provided tactile stimulation by stroking each partic-
ipant’s belly (with the wired handheld controllers of the
Razer Hydra Portal 2 Bundle), and the participant saw the
virtual hand making similar stroking movements on the
virtual body either synchronously or asynchronously with
actual tactile stimulation. During both the synchronous and
asynchronous condition, participants were asked to look
down in the direction of the belly of the virtual body that was
being stimulated. Visuo-tactile stimulation was provided by
making stroking movements on the abdomen for 90 seconds.
The order of the conditions (i.e., synchronous vs. asynchro-
nous visuo-tactile stimulation) was randomized. After each
condition, participants were asked to provide body size es-
timations of their own and the virtual body using the pro-
cedure described above. Participants also completed the
adapted version of the embodiment questionnaire after each
condition.
Data analysis
First, to verify whether the illusory feeling of ownership
of the virtual body was induced successfully, differences in
the three subscales of the embodiment questionnaire (i.e.,
ownership, self-location, and agency) were analyzed using
a repeated-measures analysis of variance, with condition
(‘‘synchronous visuo-tactile stimulation’’ vs. ‘‘asynchronous
visuo-tactile stimulation’’) and embodiment (‘‘ownership’’
vs. ‘‘self-location’’ vs. ‘‘agency’’) as within-subjects factors.
Then, to investigate the effect of embodying the virtual
body (i.e., updated egocentric body) on the participants’ re-
membered body and experienced body after the two experi-
mental conditions, following the procedure of Piryankova
et al.,
15
the ratio between the body size estimations and the
actual body size measure of the participants was calculated.
Differences in body size estimation for each body part were
calculated and subsequently compared using a separate
repeated-measures analysis of variance, with type of stored
body (‘‘remembered body’’ vs. ‘‘remembered body after
synchronous visuo-tactile stimulation’’ vs. ‘‘remembered
body after asynchronous visuo-tactile stimulation’’) as
within-subjects factor. Finally, to investigate the differences
in the perceived virtual body that participants had seen within
the two experimental conditions, a separate repeated-
measures analysis of variance for each virtual body part was
FIG. 1. The Virtual Belly
Illusion.
VIRTUAL REALITY BODY SWAPPING 129
carried out, with type of perceived virtual body (‘‘perceived
virtual body after synchronous visuo-tactile stimulation’’ vs.
‘‘perceived virtual body after asynchronous visuo-tactile
stimulation’’) as the within-subjects factor. For all of the
analyses that were conducted, the Greenhouse–Geisser test
statistic was used when the assumption of sphericity was vi-
olated. Pairwise comparisons (with Bonferroni’s adjustment)
were carried out to break down significant effects. The level
of significance was set at a = 0.05 for all statistical analyses.
Results
Data were entered into Microsoft Excel and analyzed using
SPSS Statistics for the Windows v18. Prior to this analysis, the
Kolmogorov–Smirnov test was used to check the normality of
data distribution.
First, a repeated-measures analysis of variance, with
condition (‘‘synchronous visuo-tactile stimulation’’ vs.
‘‘asynchronous visuo-tactile stimulation’’) and embodiment
(‘‘ownership,’’ ‘‘self-location’’ vs. ‘‘agency’’) as within-
subjects factors, was carried out. No significant effect of
condition or embodiment was found. Results indicated a
significant effect in the interaction between condition and
embodiment, F(1, 40) = 3.604, p < 0.05, g
2
= 0.153.
Subsequently, a paired t test showed a significant dif-
ference for the scale self-location, t =-2.29(20), p < 0.05.
Specifically, after synchronous visuo-tactile stimulation,
participants had a stronger feeling of being located inside the
virtual body (self-location after synchronous visuo-tactile
stimulation: 4.29 [0.92] and self-location after asynchro-
nous visuo-tactile stimulation: 3.68 [1.21]). Table 1 offers a
comprehensive overview of results.
Next, separate repeated-measures analyses of variance
were conducted to investigate the differences in the body
size estimation for each body part, with type of remembered
body (‘‘remembered body’’ vs. ‘‘remembered body after
synchronous visuo-tactile stimulation’’ vs. ‘‘remembered body
after asynchronous visuo-tactile stimulation’’) as within-
subjects factor. Table 2 provides a comprehensive synthesis of
the results.
As shown in Table 2, analyses yielded main effects for
type of remembered body for most of the estimated body
parts. It is interesting to note that findings revealed a dif-
ference between the ‘‘remembered body’’ and the ‘‘experi-
enced body,’’ independent of the type of visuo-tactile
stimulation. Pairwise comparisons (with Bonferroni’s ad-
justments) indicated a significant difference within the
‘‘experienced Body after synchronous visuo-tactile stimu-
lation,’’ as well as the ‘‘experienced Body after asynchro-
nous visuo-tactile stimulation,’’ only for the ratio between
estimated and actual height. Moreover, these data give sup-
port to the idea that embodying a virtual body with a skinny
belly (independent of the type of visuo-tactile stimulation)
had an effect on the ‘‘remembered body,’’ since there was a
significant decrease in the ratio between estimated and actual
body measures.
Finally, separate repeated-measures analyses of variance
for each virtual body part were carried out, with type of
Table 1. Descriptive Statistics of the Three
Subscales of the Embodiment Questionnaire
Within the Two Experimental Conditions
(i.e., Synchronous and Asynchronous
Visuo-Tactile Stimulation)
Condition of stimulation Embodiment MSD
Synchronous visuo-tactile
stimulation
Ownership 3.59 1.06
Synchronous visuo-tactile
stimulation
Self-location 4.29 0.92
Synchronous visuo-tactile
stimulation
Agency 3.73 1.64
Asynchronous visuo-tactile
stimulation
Ownership 3.64 1.68
Asynchronous visuo-tactile
stimulation
Self-location 3.68 1.21
Asynchronous visuo-tactile
stimulation
Agency 3.69 1.52
Table 2. Separate Repeated-Measures Analysis of Variance Results for Each Body Part
Body part
Remembered
body (C1)
a
Remembered body
after synchronous
visuo-tactile
stimulation (C2)
a
Remembered body
after asynchronous
visuo-tactile
stimulation (C3)
a
Fpg
2
p
C1 vs.
C2
b
C1 vs.
C3
b
C2 vs.
C3
b
Height 0.99 (0.02) 0.96 (0.02) 0.98 (0.02) 13.32 *** 0.400 ** ** **
Shoulders (width) 1.02 (0.20) 0.96 (0.21) 0.96 (0.19) 2.04 N.S. 0.152 N.S N.S. N.S.
Abdomen (width) 0.92 (0.14) 0.76 (0.18) 0.75 (0.18) 18.61 *** 0.482 ** ** N.S.
Hips (width) 0.92 (0.14) 0.88 (0.16) 0.86 (0.12) 3.22 N.S. 0.139 N.S N.S. N.S.
Shoulders (circumference) 1.52 (0.20) 1.41 (0.18) 1.42 (0.19) 12.67 *** 0.388 ** ** N.S.
Abdomen(circumference) 1.17 (0.15) 1.14 (0.12) 1.16 (0.13) 0.57 N.S. 0.028 N.S N.S. N.S.
Hips (circumference) 1.24 (0.16) 1.12 (0.10) 1.16 (0.13) 13.53 *** 0.404 *** ** N.S.
Type of remembered body (‘‘remembered body’’ vs. ‘‘remembered body after synchronous visuo-tactile stimulation’’ vs. ‘‘remembered
body after asynchronous visuo-tactile stimulation’’) is the within-subjects factor.
a
All values are reported as the ratio between the estimated body and the actual body size measure of the participants. The result of this
ratio expresses the percentage of similarity with respect to physical body, so that values near to 1 represent a remembered/experienced body
similar to the physical one. For example, a value to 0.85 of the participants’ actual size would represent an underestimation of 15%. Values
are shown as mean (SD).
b
Pairwise comparisons (with Bonferroni’s adjustment) were carried out to break down significant effects.
***p < 0.001; **p < 0.01; *p < 0.05.
N.S., not significant; ANOVA, analysis of variance.
130 SERINO ET AL.
perceived virtual body (‘‘perceived virtual body after syn-
chronous visuo-tactile stimulation’’ vs. ‘‘perceived virtual
body after asynchronous visuo-tactile stimulation’’) as within-
subjects factor to investigate the differences in the perceived
virtual body. Table 3 provides a complete overview of
results. As shown in Table 3, findings revealed only one
significant difference between the perceived shoulders of
the virtual body.
Conclusion
The current pilot study aimed to investigate whether VR
body swapping might be an effective tool for modifying the
memory of the body by embodying a first-person-perspective
virtual body with a skinny belly substituted for one’s own
real body (i.e., updated egocentric body).
First of all, in line with previous studies, the findings
confirmed that VR body swapping can be used to locate
oneself outside one’s physical body in a conscious way.
More related to the hypothesis, the results revealed that after
participants embodied a virtual body with a skinny belly
(independent of the type of visuo-tactile stimulation), there
was an update of their ‘‘remembered body.’’ Specifically,
participants reported a decrease in the ratio between esti-
mated and actual body measures for most of the body parts
considered. Furthermore, no differences were found in
transient egocentric representation related to the body avatar.
Indeed, regarding body avatar perceived measures, the data
showed only one significant difference in the perception of
the shoulders at two different stimulations. This effect likely
occurred because the virtual body’s shoulders were the only
virtual body parts that participants did not see during the
virtual exposure. Thus, they had to rely only to their imag-
ination to give an estimation. This evidence further supports
the conclusion that the illusionary ownership of a virtual
body resulted specifically in changes in the participants’ own
stored body representation, and not in the egocentric repre-
sentations related to the body avatar.
Following the Allocentric Lock Theory,
18–21
which em-
phasizes the role of spatial processing in body representations,
it is possible to suppose that the long-term representations of
the bodies had been updated by contrasting perceptual inputs
driven by parietal egocentric representations coming from VR.
It is interesting to note that there was no difference between the
effects of the synchronous and asynchronous visuo-tactile
stimulation on the experienced body. As underlined by Slater
et al.,
9
the visual first-person-perspective input was sufficient
to induce an update in the memory of the body. Multisensory
integration of visual and tactile information did not strengthen
this effect, nor did asynchronous visuo-tactile stimulation de-
crease it. These results are in line with the findings of Pir-
yankova et al.,
15
who did not find a particular effect of
synchronous visuo-tactile stimulation on the ‘‘experienced
body.’’ Indeed, other researchers have demonstrated that when
an highly realistic spatially coincident virtual body was used
to induce the illusion, an asynchronous visuo-tactile stimula-
tion was also consequently able to induce a feeling of
ownership.
31,32
These findings are also valuable for the understanding of
body representation disturbances in eating and weight dis-
orders. Recent studies using different methods have dem-
onstrated an abnormal estimation of body size in eating and
weight disorders and have conceptualized it as more than
merely a perceptual deficit, concluding that the overestima-
tion of one’s own real body may be related to a distorted
representation of one’s own body.
33–37
For example, Keizer
et al.
34
found that disturbances in body image in anorexia
nervosa (AN) were extremely profound, since they not only
affect the visual mental representation of body size but also
extend to disturbances in its somatosensory components.
Indeed, they showed that AN patients were significantly less
accurate when required to estimate the distances between
tactile stimuli on both the arm and abdomen (i.e., tactile body
image). According to the Allocentric Lock Theory,
18–21
pa-
tients suffering from eating and weight disorders are not able
to update the contents of the enduring representation of their
body. Indeed, they are locked into it. As a future challenge, it
would be helpful to investigate whether VR body swapping
could be an effective tool to induce changes in the ‘‘locked’’
body representation of patients suffering from eating and
weight disorders and to verify the difference in comparison
with a control group.
Although the methodology used did not require special-
ized training for scoring, many techniques for body part size
estimation have poor validity and reliability.
38
Dramatic ad-
vances in technology allow for more sophisticated and con-
trolled methods of measuring body size estimation. To this
end, in future studies, it would be interesting to adopt other
Table 3. Separate Repeated-Measures ANOVA Results for Each Virtual Body Part
Virtual body part
Perceived virtual
body after synchronous
visuo-tactile stimulation
Perceived virtual
body after asynchronous
visuo-tactile stimulation Fpg
2
p
Height 157.03 (7.07) 155.00 (12.03) 0.68 N.S. 0.033
Shoulders (width) 29.08 (5.76) 31.68 (5.25) 8.52 ** 0.299
Abdomen (width) 20.94 (4.14) 20.62 (4.29) 0.227 N.S 0.011
Hips (width) 27.67 (4.80) 27.34 (5.98) 0.14 N.S. 0.007
Shoulders(circumference) 107.37 (15.54) 108.83 (12.97) 0.35 N.S. 0.018
Abdomen(circumference) 91.79 (10.20) 93.21 (11.90) 0.43 N.S. 0.021
Hips (circumference) 105.15 (15.05) 104.41 (12.04) 0.081 N.S. 0.004
Type of perceived virtual body (‘‘perceived virtual body after synchronous visuo-tactile stimulation’’ vs. ‘‘perceived virtual body after
asynchronous visuo-tactile stimulation’’) as the within-subjects factor.
Values are shown as M (SD).
***p < 0.001; **p < 0.01; *p < 0.05.
VIRTUAL REALITY BODY SWAPPING 131
methodologies to assess changes in body representation, such
as the Body Image Virtual Scale
39
or the recently validated
Body Image Assessment Software.
40
In conclusion, although preliminary, these findings pro-
vide first evidence that VR body swapping is able to induce a
change in the memory of the body. Future studies may offer
the possibility to understand the potential of this approach in
a clinical population as well.
20,27,41
Acknowledgment
We thank Ordina ICT B.V. for technical development of
the VR Belly Illusion.
Author Disclosure Statement
No competing financial interests exist.
References
1. Tessari A, Tsakiris M, Borghi AM, et al. The sense of
body: a multidisciplinary approach to body representation.
Neuropsychologia 2010; 48:643–644.
2. Blanke O. Multisensory brain mechanisms of bodily self-
consciousness. Nature Reviews Neuroscience 2012; 13:
556–571.
3. Ehrsson HH, Spence C, Passingham RE. That’s my hand!
Activity in premotor cortex reflects feeling of ownership of
a limb. Science 2004; 305:875–877.
4. Tsakiris M, Haggard P. The rubber hand illusion revisited:
visuotactile integration and self-attribution. Journal of Ex-
perimental Psychology: Human Perception & Performance
2005; 31:80–91.
5. Tsakiris M, Hesse MD, Boy C, et al. Neural signatures of body
ownership: a sensory network for bodily self-consciousness.
Cerebral Cortex 2007; 17:2235–2244.
6. Lenggenhager B, Tadi T, Metzinger T, et al. Video ergo
sum: manipulating bodily self-consciousness. Science 2007;
317:1096–1099.
7. Ehrsson HH. The experimental induction of out-of-body
experiences. Science 2007; 317:1048.
8. Petkova VI, Ehrsson HH. If I were you: perceptual illusion
of body swapping. PloS One 2008; 3:e3832.
9. Slater M, Spanlang B, Sanchez-Vives MV, et al. First
person experience of body transfer in virtual reality. PloS
One 2010; 5:e10564.
10. Jeon B, Cho S, Lee JH. Application of virtual body
swapping to patients with complex regional pain syndrome:
a pilot study. Cyberpsychology, Behavior, & Social Net-
working 2014; 17:366–370.
11. Slater M, Perez-Marcos D, Ehrsson HH, et al. Inducing illu-
sory ownership of a virtual body. Frontiers in Neuroscience
2009; 3:214.
12. Kilteni K, Normand JM, Sanchez-Vives MV, et al. Extending
body space in immersive virtual reality: a very long arm il-
lusion. PloS One 2012; 7:e40867.
13. Normand JM, Giannopoulos E, Spanlang B, et al. Multi-
sensory stimulation can induce an illusion of larger belly
size in immersive virtual reality. PloS One 2011; 6:e16128.
14. van der Hoort B, Guterstam A, Ehrsson HH. Being Barbie:
the size of one’s own body determines the perceived size of
the world. PloS One 2011; 6:e20195.
15. Piryankova IV, Wong HY, Linkenauger SA, et al. Owning
an overweight or underweight body: distinguishing the
physical, experienced and virtual body. PloS One 2014;
9:e103428.
16. Ehrsson HH, Kito T, Sadato N, et al. Neural substrate of
body size: illusory feeling of shrinking of the waist. PLoS
Biology 2005; 3:e412.
17. Preston C, Ehrsson HH. Illusory changes in body size
modulate body satisfaction in a way that is related to non-
clinical eating disorder psychopathology. PloS One 2014;
9:e85773.
18. Riva G. Neuroscience and eating disorders: the allocentric
lock hypothesis. Medical Hypotheses 2012; 78:254–257.
19. Riva G, Gaudio S. Allocentric lock in anorexia nervosa:
new evidences from neuroimaging studies. Medical Hy-
potheses 2012; 79:113–117.
20. Riva G, Gaudio S, Dakanalis A. I’m in a virtual body: a
locked allocentric memory may impair the experience of
the body in both obesity and anorexia nervosa. Eating &
Weight disorders 2014; 19:133–134.
21. Riva G. Out of my real body: cognitive neuroscience meets
eating disorders. Frontiers in Human Neuroscience 2014;
8:236.
22. Klatzky RL (1998) Allocentric and egocentric spatial re-
presentations: Definitions, distinctions, and interconnections.
In: Freksa C., Habel, C., Wender, K. F., eds. Spatial cognition.
An interdisciplina ry approach to representing and processing
spatial knowledge. Springer Berlin Heidelberg, pp. 1–17.
23. Paillard J. (1991) Brain and space. Oxford: Oxford-
Science.
24. Burgess N, Becker S, King JA, et al. Memory for events
and their spatial context: models and experiments. Philo-
sophical Transactions of the Royal Society of London
Series B: Biological Sciences 2001; 356:1493–1503.
25. Byrne P, Becker S, Burgess N. Remembering the past and
imagining the future: a neural model of spatial memory and
imagery. Psychological Review 2007; 114:340.
26. Cesa GL, Manzoni GM, Bacchetta M, et al. Virtual reality
for enhancing the cognitive behavioral treatment of obesity
with binge eating disorder: randomized controlled study
with one-year follow-up. Journal of Medical Internet Re-
search 2013; 15:e113.
27. Riva G, Gaudio S, Dakanalis A. The neuropsychology
of self-objectification. European Psychologist, 2015; 20:
34–43.
28. Sheehan DV, Lecrubier Y, Sheehan KH, et al. The Mini-
International Neuropsychiatric Interview (M.I.N.I.): the
development and validation of a structured diagnostic
psychiatric interview for DSM-IV and ICD-10. The Journal
of Clinical Psychiatry 1998; 59:34–57.
29. Rossi A, Alberio R, Porta A, et al. The reliability of the
MINI-international neuropsychiatric interview-Italian ver-
sion. Journal of Clinical Psychopharmacology 2004;
24:561–563.
30. Garner DM, Olmsted MP, Bohr Y, et al. The eating atti-
tudes test: psychometric features and clinical correlates.
Psychological Medicine 1982; 12:871–878.
31. Maselli A, Slater M. The building blocks of the full body
ownership illusion. Frontiers in Human Neuroscience 2013;
7:83.
32. Longo MR, Cardozo S, Haggard P. Visual enhancement of
touch and the bodily self. Consciousness & Cognition
2008; 17:1181–1191.
33. Smeets MAM, Ingleby JD, Hoek HW, et al. Body size
perception in anorexia nervosa: a signal detection approach.
Journal of Psychosomatic Research 1999; 46:465–477.
132 SERINO ET AL.
34. Keizer A, Smeets MAM, Dijkerman HC, et al. Tactile body
image disturbance in anorexia nervosa. Psychiatry Re-
search 2011; 190:115–120.
35. Guardia D, Lafargue G, Thomas P, et al. Anticipation of
body-scaled action is modified in anorexia nervosa. Neu-
ropsychologia 2010; 48:3961–3966.
36. Keizer A, Smeets MAM, Dijkerman HC, et al. Too fat to fit
through the door: first evidence for disturbed body-scaled
action in anorexia nervosa during locomotion. PloS One
2013; 8:e64602.
37. Scarpina F, Castelnuovo G, Molinari E. Tactile mental
body parts representation in obesity. Psychiatry Research
2014; 220:960–969.
38. Gardner RM, Brown DL. (2011) Measurement of the per-
ceptual aspects of body image. In Greene SB, ed. Body im-
age: perceptions, interpretations and attitudes. New York:
Nova Science, pp. 81–102.
39. Riva G. Virtual reality in psychological assessment: the
body image virtual reality scale. CyberPsychology & Be-
havior 1998; 1:37–44.
40. Ferrer-Garcı
´
a M, Gutie
´
rrez-Maldonado J. Body image as-
sessment software: psychometric data. Behavior Research
Methods 2008; 40:394–407.
41. Riva G., Gaggioli A., Dakanalis A. From body dis-
satisfaction to obesity. How virtual reality may improve
obesity prevention and treatment in adolescents. Stud
Health Technol Inf 2013; 184:356–362.
Address correspondence to:
Dr. Silvia Serino
Applied Technology for Neuro-Psychology Lab
IRCCS Istituto Auxologico Italiano
Via Magnasco, 2
20149 Milan
Italy
E-mail: s.serino@auxologico.it
VIRTUAL REALITY BODY SWAPPING 133
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