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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 ("synchronous 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.
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Virtual Reality Body Swapping:
A Tool for Modifying the Allocentric
Memory of the Body
Silvia Serino, PhD,
Elisa Pedroli, PsyD,
Anouk Keizer, PhD,
Stefano Triberti, MA,
Antonios Dakanalis, PhD,
Federica Pallavicini, PhD,
Alice Chirico, MA,
and Giuseppe Riva, PhD
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
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.
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
Recently, many interesting studies have used different
techniques to induce multisensory conflict to investigate
these aspects of bodily self-consciousness.
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.
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.,
Normand et al.,
van der Hoort
et al.,
Piryankova et al.,
and Ehrsson et al.
). Indeed, in
Applied Technology for Neuro-Psychology Lab, IRCCS Istituto Auxologico Italiano, Milan, Italy.
Department of Experimental Psychology, Faculty of Social and Behavioral Sciences, Utrecht University, Utrecht, Netherlands.
Department of Psychology, Catholic University of the Sacred Heart, Milan, Italy.
Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy.
Department of Surgery and Interdisciplinary Medicine, University of Milano-Bicocca, Milan, Italy.
Centre for Studies in Communication Sciences—CESCOM, University of Milano-Bicocca, Milan, Italy.
Volume 19, Number 2, 2016
ª Mary Ann Liebert, Inc.
DOI: 10.1089/cyber.2015.0229
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.,
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.
However, Piryankova et al.
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
—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.
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
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).
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?
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
Twenty-one female participants from the Catholic Uni-
versity of the Sacred Heart, Milan, Italy (M
= 22.76 years,
SD = 2.42 years; M
= 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
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
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.
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
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).
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,
and Eating Attitude
) 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
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.,
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
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.
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
= 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
Ownership 3.59 1.06
Synchronous visuo-tactile
Self-location 4.29 0.92
Synchronous visuo-tactile
Agency 3.73 1.64
Asynchronous visuo-tactile
Ownership 3.64 1.68
Asynchronous visuo-tactile
Self-location 3.68 1.21
Asynchronous visuo-tactile
Agency 3.69 1.52
Table 2. Separate Repeated-Measures Analysis of Variance Results for Each Body Part
Body part
body (C1)
Remembered body
after synchronous
stimulation (C2)
Remembered body
after asynchronous
stimulation (C3)
C1 vs.
C1 vs.
C2 vs.
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.
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).
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.
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.
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,
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.,
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.,
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
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.
For example, Keizer
et al.
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,
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.
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
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.
methodologies to assess changes in body representation, such
as the Body Image Virtual Scale
or the recently validated
Body Image Assessment Software.
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.
We thank Ordina ICT B.V. for technical development of
the VR Belly Illusion.
Author Disclosure Statement
No competing financial interests exist.
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Address correspondence to:
Dr. Silvia Serino
Applied Technology for Neuro-Psychology Lab
IRCCS Istituto Auxologico Italiano
Via Magnasco, 2
20149 Milan
This article has been cited by:
1. Riva Giuseppe, Gutiérrez-Maldonado José, Wiederhold Brenda K.. 2016. Virtual Worlds versus Real Body: Virtual Reality Meets
Eating and Weight Disorders. Cyberpsychology, Behavior, and Social Networking 19:2, 63-66. [Citation] [Full Text HTML] [Full
Text PDF] [Full Text PDF with Links]
2. Antonios Dakanalis, Alix Timko, Silvia Serino, Giuseppe Riva, Massimo Clerici, Giuseppe Carrà. 2016. Prospective Psychosocial
Predictors of Onset and Cessation of Eating Pathology amongst College Women. European Eating Disorders Review n/a-n/a.
... Twenty-four studies examined the effect of embodiment illusions on BID using perceptual and/or cognitive-affective measures. Twenty (83.33%) observed small to largesized (predominately medium to large-sized) improvements post-embodiment (Carey & Preston, 2019;Ferrer-Garcia et al., 2018;Keizer et al., 2014;Lin et al., 2021;Liu et al., 2022;Malighetti et al., 2021;Neyret et al., 2020;Piryankova et al., 2014;Porras-Garcia et al., 2019;2021;Preston & Ehrsson, 2014;Scarpina et al., 2019;Serino et al., 2016;Tambone et al., 2021;Themelis et al., 2021;Wolf et al., 2021). Of these 20, five also reported negative modifications (i.e., a more negative rating on a cognitive-affective scale or increased body size estimation/misestimation), generally involving medium or largesized effects (Ferrer-Garcia et al., 2018;Lin et al., 2021;Preston & Ehrsson, 2018;Tambone et al., 2021;Themelis et al., 2021). ...
... Of the 24 studies, 22 induced a VR-based fullbody illusion: 18 (81.80%) found medium or large-sized improvements in BID across perceptual and/or cognitive-affective dimensions (Ferrer-Garcia et al., 2018;Keizer et al., 2016;Lin et al., 2021, Liu et al., 2022Malighetti et al., 2021;Neyret et al., 2020;Piryankova et al., 2014;Porras-Garcia et al., 2019;2021;Preston & Ehrsson, 2014;Scarpina et al., 2019;Serino et al., 2016;Tambone et al., 2021;Themelis et al., 2021;Wolf et al., 2021); and four observed medium to large-sized negative modifications alone across both dimensions (Ferrer-Garcia et al., 2017;Normand et al., 2011;Porras-Garcia et al., 2020) or a non-discernible non-significant small change (Provenzano et al., 2019). The All rights reserved. ...
... Of the 20 studies that found improvements in BID, nine stimulated the abdomen alone, generally involving medium to large-sized improvements Neyret et al., 2020;Preston & Ehrsson, 2014;Scarpina et al., 2019;Serino et al., 2016;Tambone et al., 2021). Two stimulated the hand alone and produced small to large-sized improvements (Carey & Preston, 2019;Keizer et al., 2014). ...
Embodiment illusions, which manipulate multisensory integration processes underlying self-perception, are increasingly used to understand and improve body image disturbance (BID): a core symptom of eating disorders (EDs) and body dysmorphic disorder (BDD). The current systematic review is the first to evaluate clinical and community-based evidence on whether (i) variations involving BID impact embodiment illusion susceptibility and (ii) embodiment illusions can improve BID. Thirty-two studies met inclusion criteria. Greater embodiment was generally observed among individuals with high (relative to low/no) BID (9 out of 14 studies; 64.29%). Embodiment produced an improvement in BID in most studies (20 out of 24; 83.33%). Effect sizes were generally medium to large across both findings. Although several issues exist within the literature (e.g., substantial methodological heterogeneity, non-validated measures), findings reiterate that disturbances in multisensory integration appear to underpin BID, although embodiment illusions offer opportunities to develop new therapeutic interventions for BID. Multiple factors are of particular interest for ensuring that embodiment illusion paradigms are best designed for future research and application (e.g., virtual reality versus real-world methods).
... The body schema almost exclusively uses information from the haptic system. Visual information can briefly, but not permanently, alter the body schema in the form of illusions or during tool use (Braun et al. 2014;Haans et al. 2012;Baccarini et al. 2014;Serino et al. 2016;Aymerich-Franch and Ganesh 2016;Hornburger et al. 2019;Romano et al. 2019;Sun and Tang 2019;Olgiati et al. 2017;Martel et al. 2016;Laessoe et al. 2017). The molecular, biological, neuronal, and cortical aspects of the body schema have not yet been fully understood scientifically. ...
The haptic system encompasses three perceptual dimensions: (1) exteroception (perception of physical and some chemical properties of the external world), (2) interoception/visceroception (processing and regulation of the states of the body and its organ functions), and (3) proprioception (perception of limb and body movements and position in space). While all other sensory systems have specialized receptors that are concentrated in a specific region of the body (eye, ear, nose, mouth), the mechanoreceptors of the haptic system are located in varying concentrations throughout the body, and therefore, the perceptual functions of the haptic system involve the entire body. This chapter gives detailed information about exteroceptive, interoceptive, and proprioceptive processes of the haptic system, temperature and pain perception, and the development and relevance of body schema and body image.
... As a result, our findings supporting the use of 360° technology for bodily illusions could be exploited for the development of psychological novel interventions targeting conditions in which the "allocentric" memory of the body is altered (e.g., eating disorders) (Riva et al. 2014(Riva et al. , 2017 or where there is an abnormal sense of self-location, and people undergo out-of-body experiences, assuming a 3PP and experiencing disembodiment: post-traumatic stress disorder with dissociative symptoms (Rabellino et al. 2018), depersonalization/derealization disorder, panic attacks (Sierra and David 2011), or dissociative symptoms in victims of sexual harassment (Adams-Clark et al. 2019). As already shown in the study of Serino et al. (2016), body illusions may be useful to support people with such difficulties, updating the stored (allocentric) representation of their bodies. Finally, our last objective was to explore possible individual differences in the strength of the body illusion. ...
Full-text available
Illusions that create a sense of ownership over a virtual body have been widely used to investigate the characteristics of our bodily experience. Despite the great potential of 360-degree videos to implement full-body ownership illusion, research is in its early stages, and no validated tools—neither commercial nor free—are available for the scientific and clinical community. In the current study, we present and discuss the development and feasibility results of a free 360-degree video-based body ownership illusion that researchers and scholars can experience using a cardboard headset with their smartphones. Forty-six participants underwent the 360-degree video-based full-body ownership illusion, visualizing in a first-person perspective (1PP) or in a mirror view the pre-recorded body of a young female performer. All participants were exposed to a congruent visuo-tactile condition (embodiment condition) and to an incongruent visuo-tactile condition (control condition). Participants completed the Embodiment Questionnaire and the Objectified Body Consciousness (OBC) scale. Results revealed that in the congruent visuo-tactile condition (compared to the control one), participants experienced a strong illusion in terms of body ownership, self-location, and agency. In terms of visual perspective, there was no difference in embodiment feelings between participants who experienced the illusion in 1PP and those who underwent a mirror perspective. Lastly, the control beliefs subscale (i.e., OBC scale) displayed a positive correlation with the self-location illusion susceptibility. Overall, these results point to the feasibility of this novel tool as immersive 360-degree video-based scenarios to deliver bodily illusions, and they open new avenues for future clinical interventions.
... Accordingly, the perception of the stigma as a "patient" referring to illness characteristics could decrease individuals' empowerment, improving shame and social isolation (Amini-Tehrani et al., 2021;Brunet and Price, 2021). Virtual reality (VR), as a tool that allows users to experience a sense of belonging with a body in a virtual world (virtual reality full body illusion), is generally involved in promoting body awareness and regulation of emotional wellbeing, especially in the eating disorder fields (Slater et al., 2008;Serino et al., 2016;So et al., 2022). Starting with the process of embodiment and the sense of presence, users can, therefore, perceive their real and virtual bodies simultaneously (Ventura et al., 2018). ...
Full-text available
Women who received a diagnosis of breast cancer often report impairments in physical and psychological wellbeing, even some years after treatments. Individual awareness about physical changes, body image, and current sensations related to their body is important to maintain a psycho-emotional balance. Virtual reality, as an advanced human–computer interface, can be an effective tool to improve breast cancer survivors' abilities to know and manage their current sensations related to their bodies. The present study protocol proposes a virtual reality intervention aiming at promoting interoception and emotional wellbeing, fear of cancer recurrence, and body perception in breast cancer survivors, according to the three data collection times. Repeated-measure analysis of variance (ANOVA) with between–within interaction will be performed. Expected results include participants' awareness of their internal feelings, the reduction of negative emotions, and the management of symptoms related to the body, clarifying characteristics for the effective implementation of VR psychological intervention in the future.
... As VR tools for psychotherapy have progressed, there have been calls to link clinical considerations with technical implementation from the outset, including the choice of hardware and specific software characteristics [17,18]. Studies using VR for therapeutic applications in eating disorders have recently increased (for reviews, see [19,20]), but existing setups for virtual body exposure are either technically rough but accessible (e.g., [21,22]) or complex and bound to the developing laboratory (e.g., [23,24]). Other differences include strategies to induce body ownership [25] and therapeutic rationales [19,26,27]. ...
Full-text available
Introduction/objective: Treatment results of anorexia nervosa (AN) are modest, with fear of weight gain being a strong predictor of treatment outcome and relapse. Here, we present a virtual reality (VR) setup for exposure to healthy weight and evaluate its potential as an adjunct treatment for AN. Methods: In two studies, we investigate VR experience and clinical effects of VR exposure to higher weight in 20 women with high weight concern or shape concern and in 20 women with AN. Results: In study 1, 90% of participants (18/20) reported symptoms of high arousal but verbalized low to medium levels of fear. Study 2 demonstrated that VR exposure to healthy weight induced high arousal in patients with AN and yielded a trend that four sessions of exposure improved fear of weight gain. Explorative analyses revealed three clusters of individual reactions to exposure, which need further exploration. Conclusions: VR exposure is a well-accepted and powerful tool for evoking fear of weight gain in patients with AN. We observed a statistical trend that repeated virtual exposure to healthy weight improved fear of weight gain with large effect sizes. Further studies are needed to determine the mechanisms and differential effects.
... The use of BIs in the treatment of eating disorders is VR justified by recent theories (Riva, 2014;Serino et al., 2015;Riva and Dakanalis, 2018;Riva and Gaudio, 2018) according to which these clinical conditions could be related to an impairment in the multisensory body integration, that determine a deficit in updating the body representations (Riva and Gaudio, 2018). In this view, VR can help the patients to update the wrong body representation thanks to the body-swapping strategy (Serino et al., 2016) -a full body illusion where the patient "wears" a virtual body that differs from the real one in size or shape. Recently this approach has been applied to obesity (Scarpina et al., 2019) and anorexia (Porras-Garcia et al., 2020). ...
Full-text available
The body is a very special object, as it corresponds to the physical component of the self and it is the medium through which we interact with the world. Our body awareness includes the mental representation of the body that happens to be our own, and traditionally has been defined in terms of body schema and body image. Starting from the distinction between these two types of representations, the present paper tries to reconcile the literature around body representations under the common framework of body memory. The body memory develops ontogenetically from birth and across all the life span and is directly linked to the development of the self. Therefore, our sense of self and identity is fundamentally based on multisensory knowledge accumulated in body memory, so that the sensations collected by our body, stored as implicit memory, can unfold in the future, under suitable circumstances. Indeed, these sets of bodily information had been proposed as possible key factors underpinning several mental health illnesses. Following this perspective, the Embodied Medicine approach put forward the use of advanced technologies to alter the dysfunctional body memory to enhance people's well-being. In the last sections, recent experimental pieces of evidence will be illustrated that targeted specifically bodily information for increasing health and wellbeing, by means of two strategies: interoceptive feedback and bodily illusions. See also Figure 1(Fig. 1).
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Individuals with Anorexia Nervosa and Bulimia Nervosa present alterations in the way they experience their bodies. Body experience results from a multisensory integration process in which information from different sensory domains and spatial reference frames is combined into a coherent percept. Given the critical role of the body in the onset and maintenance of both Anorexia Nervosa and Bulimia Nervosa, we conducted a systematic review to examine multisensory integration abilities of individuals affected by these two conditions and investigate whether they exhibit impairments in crossmodal integration. We searched for studies evaluating crossmodal integration in individuals with a current diagnosis of Anorexia Nervosa and Bulimia Nervosa as compared to healthy individuals from both behavioral and neurobiological perspectives. A search of PubMed, PsycINFO, and Web of Sciences databases was performed to extract relevant articles. Of the 2348 studies retrieved, 911 were unique articles. After the screening, 13 articles were included. Studies revealed multisensory integration abnormalities in patients affected by Anorexia Nervosa; only one included individuals with Bulimia Nervosa and observed less severe impairments compared to healthy controls. Overall, results seemed to support the presence of multisensory deficits in Anorexia Nervosa, especially when integrating interoceptive and exteroceptive information. We proposed the Predictive Coding framework for understanding our findings and suggested future lines of investigation.
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Introduction We aim to examine the usability of a Virtual Reality (VR) platform, called ConVRSelf, which has been designed to address the needs of People Living With Obesity (PLWO). Methods Fourteen participants with a desire to eat healthier and exercise more (6 normal weight and 8 PLWO; Mean age = 41.86, SD = 13.89) were assigned to the experimental group (EG) or the control group (CG). EG participants, after being trained on motivational interviewing skills, engaged in a virtual self-conversation using embodiment and body swapping techniques, which aimed to normalize and resolve their ambivalence to change lifestyle habits. CG participants, embodied in their virtual bodies, participated in a pre-established discourse with a virtual counselor giving them psychoeducational advice about how to change lifestyle habits. A mixed-methods design was used, involving a semi-structured interview and self-report questionnaires, including readiness to change habits (Readiness Rulers), body ownership (Body Ownership Questionnaire, BOQ), and system usability (System Evaluation Questionnaire, SEQ). Thematic content analysis was carried out for qualitative data while statistical data analysis was carried out using SPSS 20.0. Results Participants from both groups showed high readiness to change lifestyle (Readiness Rulers) before engaging with the virtual experiences, which was maintained at the same level after the interventions and their scores on the SEQ and BOQ were satisfactory. Regarding qualitative information obtained from the interviews, almost all participants found the VR experience to be novel, interesting, and enjoyable. A higher acceptability was observed among PLWO from the EG than normal weight participants from the same group, a promising finding for the ConVRSelf platform, which had been specifically designed to address the needs of PLWO. Conclusion The ConVRSelf system is well-accepted by participants and is ready to be tested with PLWO in a clinical setting.
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This Special Issue presents and discusses a collection of authoritative studies suggesting that computer generated graphic environments—virtual reality (VR) and augmented reality (AR)—can integrate and extend existing prevention, assessment, and treatment protocols for eating and weight disorders (EWDs). Recent studies, summarized in the review by Wiederhold et al. opening this Special Issue, indicate that VR and AR can integrate and extend existing prevention, assessment, and treatment protocols for EWDs. The first section of the Special Issue showcases the potential of VR in supporting and improving health behavior change for the prevention and treatment of EWDs. The second section of the Special Issue includes different articles focusing on the use of VR and AR for assessing and improving attitudes, attention, and emotions. The final section of the Special Issue explores in more detail the clinical use of VR in both assessment and treatment. In particular, this Special Issue provides strong preliminary evidence to justify future research to identify the most effective technological interventions, and the optimal amount of technological support needed, for supporting health behavior change, reducing body image and anti-fat attitudes, and extending existing cue-exposure and CBT protocols.
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The course of college women's eating pathology is variable. Little is known about psychosocial factors prospectively predicting maintenance/cessation or the new onset of clinically significant disordered eating symptoms. This study aimed to address these research gaps. College women (N = 2202) completed an assessment of eating pathology and potential risk/maintenance factors at two time points, 9 months apart. Logistic regression models indicated that elevated body dissatisfaction, thin-ideal internalization, self-objectification, negative affectivity and lower self-esteem at baseline predicted 'onset' of clinically significant disordered eating symptomatology at follow-up. Greater self-esteem and lower initial levels on the remaining risk factors predicted subsequent 'cessation' of clinically significant disordered eating symptoms. Self-objectification had greater explanatory value with regard to 'cessation' and 'onset' relative to the remaining traditionally accepted factors that demonstrated half as much predictive power or less. Practical implications are discussed. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association.
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Body image disturbance (BID) is an important aspect of several pathologies in psychology, particularly eating disorders. BID is commonly thought to include two components; a perceptual component and an attitudinal component. The perceptual component refers to how accurately individuals perceive the size of their body, also known as body size estimation or BSE. The attitudinal component refers to the thoughts and feelings one has about the size and/or shape of their body, which is also known as body dissatisfaction. While both components have been shown to play an important role in eating disorders, they are largely independent of each other. This chapter reviews the clinical relevance of measuring BSE in relation to eating disorders and provides an overview of research findings. A broad historical overview is provided that highlights the various techniques that have been developed to assess BSE including analogue scales, image marking, optical distortion methods, and figural drawing scales. Analogue scales require participants to adjust the horizontal distance of a pair of calipers or two points of light to show the width of various body parts. Image marking procedures require participants to draw their body on a vertically mounted piece of paper or to mark on the paper the width of certain body parts. Recent optical distortion methods typically employ computer software that presents the participant with an image of themselves that has been distorted in width and participants are asked to adjust the image to match both the actual and ideal size of their body. These images are typically static digital images, although photographs have occasionally been used as well. Each method is discussed along with any relevant limitations or methodological concerns. Psychophysical techniques such as the method of constant stimuli, signal detection theory, and adaptive probit estimation are described in relation to methodological concerns such as distinguishing sensory from non-sensory components of BSE. Video distortion techniques that incorporate psychophysical techniques appear to be the most precise for measuring BSE.
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Virtual environments (VEs) are attracting much attention in clinical psychology, especially in the treatment of phobias. However, a possible new application of virtual reality (VR) in psychology is as assessment tool: VEs can be considered as a highly sophisticated form of adaptive testing. In fact, the key characteristic of VEs is the high level of control of the interaction with the tool without the constraints usually found in computer systems. Both the synthetic environment itself and the manner in which this environment is modified by the user's responses can be tailored to the needs of each client and/or therapeutic application. This article describes the context of current psychological assessment and underlines possible advantages of a VR-based assessment tool. It also details the characteristics of the Body Image Virtual Reality Scale, an assessment tool designed to assess cognitive and affective components of body image. It consists of a nonimmersive 3D graphical interface through which the patient is able to choose among seven figures that vary in size from underweight to overweight.
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Our bodies are the most intimately familiar objects we encounter in our perceptual environment. Virtual reality provides a unique method to allow us to experience having a very different body from our own, thereby providing a valuable method to explore the plasticity of body representation. In this paper, we show that women can experience ownership over a whole virtual body that is considerably smaller or larger than their physical body. In order to gain a better understanding of the mechanisms underlying body ownership, we use an embodiment questionnaire, and introduce two new behavioral response measures: an affordance estimation task (indirect measure of body size) and a body size estimation task (direct measure of body size). Interestingly, after viewing the virtual body from first person perspective, both the affordance and the body size estimation tasks indicate a change in the perception of the size of the participant's experienced body. The change is biased by the size of the virtual body (overweight or underweight). Another novel aspect of our study is that we distinguish between the physical, experienced and virtual bodies, by asking participants to provide affordance and body size estimations for each of the three bodies separately. This methodological point is important for virtual reality experiments investigating body ownership of a virtual body, because it offers a better understanding of which cues (e.g. visual, proprioceptive, memory, or a combination thereof) influence body perception, and whether the impact of these cues can vary between different setups.
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Clinical psychology is starting to explain eating disorders (ED) as the outcome of the interaction among cognitive, socio-emotional and interpersonal elements. In particular two influential models-the revised cognitive-interpersonal maintenance model and the transdiagnostic cognitive behavioral theory-identified possible key predisposing and maintaining factors. These models, even if very influential and able to provide clear suggestions for therapy, still are not able to provide answers to several critical questions: why do not all the individuals with obsessive compulsive features, anxious avoidance or with a dysfunctional scheme for self-evaluation develop an ED? What is the role of the body experience in the etiology of these disorders? In this paper we suggest that the path to a meaningful answer requires the integration of these models with the recent outcomes of cognitive neuroscience. First, our bodily representations are not just a way to map an external space but the main tool we use to generate meaning, organize our experience, and shape our social identity. In particular, we will argue that our bodily experience evolves over time by integrating six different representations of the body characterized by specific pathologies-body schema (phantom limb), spatial body (unilateral hemi-neglect), active body (alien hand syndrome), personal body (autoscopic phenomena), objectified body (xenomelia) and body image (body dysmorphia). Second, these representations include either schematic (allocentric) or perceptual (egocentric) contents that interact within the working memory of the individual through the alignment between the retrieved contents from long-term memory and the ongoing egocentric contents from perception. In this view EDs may be the outcome of an impairment in the ability of updating a negative body representation stored in autobiographical memory (allocentric) with real-time sensorimotor and proprioceptive data (egocentric).
Previous work has reported that it is not difficult to give people the illusion of ownership over an artificial body, providing a powerful tool for the investigation of the neural and cognitive mechanisms underlying body perception and self consciousness. We present an experimental study that uses immersive virtual reality focused on identifying the perceptual building blocks of this illusion. We systematically manipulated visuotactile and visual sensorimotor contingencies, visual perspective, and the appearance of the virtual body in order to assess their relative role and mutual interaction. Consistent results from subjective reports and physiological measures showed that a first person perspective over a fake humanoid body is essential for eliciting a body ownership illusion. We found that the level of realism of the virtual body, in particular the realism of skin tone, plays a critical role: when high enough, the illusion can be triggered by the sole effect of the spatial overlap between the real and virtual bodies, providing congruent visuoproprioceptive information, with no need for the additional contribution of congruent visuotactile and/or visual sensorimotor cues. Additionally, we found that the processing of incongruent perceptual cues can be modulated by the level of the illusion: when the illusion is strong, incongruent cues are not experienced as incorrect. Participants exposed to asynchronous visuotactile stimulation can experience the ownership illusion and perceive touch as originating from an object seen to contact the virtual body. Analogously, when the level of realism of the virtual body and/or the spatial overlap of the two bodies is not high enough, the contribution of congruent multisensory and/or sensorimotor cues is required for evoking the illusion. On the basis of these results and inspired by findings from neurophysiological recordings in the monkey, we propose a model that accounts for many of the results reported in the literature.
Abstract This study aimed to apply virtual body swapping through mental rehearsal for patients with complex regional pain syndrome (CRPS) and to investigate whether it is applicable to them. Ten patients who met the diagnostic criterion for CRPS type 1 were randomly assigned to either the treatment or control group. All participants were asked to watch the virtual body swapping training video clip with a head mounted display. The treatment group was additionally asked to assume a posture similar to the body on the screen and rehearse the movements mentally, as if the body presented on the screen was their body. No difference between the groups was found for pain intensity, however, the treatment group showed significantly more improvement in body perception disturbance (BPD) after the treatment than the control group. Even if the presented study is a preliminary one, the above results suggest that virtual body swapping through mental rehearsal is applicable for patients with CRPS and may be useful for improving BPD. The limitations of the study and the future investigations needed to provide clearer clinical suggestions are presented and discussed.