REVIEW ARTICLE
Virtual reality as a mechanism for exposure therapy
MARCELE REGINE DE CARVALHO, RAFAEL C. FREIRE & ANTONIO EGIDIO NARDI
Laboratory of Panic and Respiration, Institute of Psychiatry, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro
(RJ), Brazil
AbstractVirtual reality (VR) is as effective in inducing emotional responses as reality and its application is extremely valuable inexposure treatment. In virtual environments, the patients experience similar physiological symptoms and fear as they do inreal life situations, thereby facilitating the habituation process. Our goal is to offer an overview of the current panorama ofVR and psychotherapy, underlining the (virtual) exposure technique and the studies that focus on panic disorder treatmentthrough the use of VR. The literature was revised through consultation to the ISI and PubMed databases. Virtual exposuretreatment offers good results and great patient acceptability. However, despite the importance of this data for the evaluationof treatment efficacy, only a few studies measure physiological responses during exposure. Lack of controlled studies andstandardized treatment protocols were observed. Despite the great advance of VR use in psychotherapy, a great deal of itspotential is still unknown, therefore requiring the creation of new virtual environments so that controlled studies regardingits clinical application can be conducted. Throughout the process of elaboration and investigation, clinical experiences invirtual environments must be related to real experiences in a flexible context that combines relevant cultural, physical andcognitive aspects.
Key words: Behaviour therapy, cognitive behaviour therapy, exposure therapy, panic disorder, virtual reality
Introduction
The introduction of new technology in the mental
health field may be a means of enhancing the efficacy
or increasing the possibilities of diagnosis and
intervention in traditional treatments. As a result of
recent technological development, a great innovation
has been improved in the field of psychotherapy �the use of virtual reality (VR). Wiederhold (2000)
demonstrates this scenario through the increase in
the number of exhibitions and printed material on
VR in psychiatry and psychology in the 1990s. No
material dated 1993 was found and only two
professional presentations on the theme. However,
in 1999, 77 presentations were made and 53 reports
were published. The period peaked in 1998, with 61
publications. Currently, in the PubMed data bank
alone, a simple search using the keywords virtual
reality will lead to over 2000 articles on this subject.
In cognitive-behavioural therapy, the use of ex-
posure in intervention has already been validated
and can be extended to virtual environments accord-
ing to the patient’s specific needs. Exposure in
virtual environments has proven to be efficacious
in treating several disorders; such as acrophobia
(Emmelkamp et al. 2001, 2002), spider phobia
(Garcia-Palacios et al. 2002), fear of flying (Roth-
baum et al. 2000, 2002; Maltby et al. 2002;
Wiederhold et al. 2002a), claustrophobia (Botella
et al. 1999, 2000), driving phobia (Wald and Taylor
2003), social phobia (Klinger et al. 2005), binge
eating disorder (Riva et al. 2003), body image
disturbance (Riva et al. 2001) post-traumatic stress
disorder (Rothbaum et al. 1999), and different kinds
of patients � those that do not use computers and
those that have close contact with this technology
(Wiederhold and Wiederhold 2000). According to
Parsons and Rizzo (2008) virtual exposure is rela-
tively effective from a psychotherapeutic standpoint
in carefully selected patients and can reduce anxiety
and phobia symptoms.
However, it should be noted that the introduction
of technology does not represent a new theoretical
approach in psychotherapy. The goal is, above all, to
enhance the treatments that already exist and
expand the utility of techniques that have already
Correspondence: Marcele Regine de Carvalho, Rua Desembargador Izidro 40/504, Tijuca, Rio de Janeiro (RJ), CEP 20521-160, Brasil.
Tel: �55 21 2436 8202. Fax: �55 21 2523 6839. E-mail: [email protected]
The World Journal of Biological Psychiatry, 2010; 11(2): 220�230
(Received 15 July 2008; accepted 22 October 2008)
ISSN 1562-2975 print/ISSN 1814-1412 online # 2010 Informa UK Ltd. (Informa Healthcare, Taylor & Francis AS)
DOI: 10.3109/15622970802575985
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been applied (Riva et al. 2002a). In so doing, the
fundamental elements of psychotherapy are pre-
served, such as the therapeutic relationship and the
relevant use of the techniques that have already been
established. The therapist remain critical, the com-
puter is simply one more tool at the disposition of
the professional (Glantz et al. 2003).
Castelnuovo et al. (2003) add that focus should
not be on technology but on the psychotherapeutic
process, that can be enhanced through the use of
technological tools. Thus, the use of VR, as well as
other strategies available in the field of psychology,
should not be random but in conformity with the
patient’s needs. That is why studies in this field that
point to when VR should be used are so important.
The aim of this study is to present a systematic
review of the literature available on VR and psy-
chotherapy, with special attention given to the
exposure technique, an important component of
the Cognitive-Behavioural Therapy, and the studies
that focus on treatment of Panic Disorder (PD).
Methods
The bibliographical search was carried out in the ISI
and PubMed data banks using the keywords: virtual
reality and panic disorder; virtual reality and anxiety
disorders. Only literature reviews or meta-analysis
articles were selected on virtual reality and anxiety
disorders keywords’ search. The search was not
limited by the date of article publication. The
selection used articles published in English. The
references of the selected articles were used as
research source. Using the references as a starting
point, articles on PD and VR were selected as well as
those that contained concepts on exposure related to
VR and the concept of presence. Seventy-four
articles were selected: 46 originals, 20 literature
reviews or meta-analysis, three case reports, four
commentaries on a published article, one introduc-
tion to a journal special issue.
Virtual reality and the presence experience
The term ‘‘virtual reality’’ is usually applied to real-
time interaction with three-dimensional (3D) com-
puter-generated environments (Wilson et al. 1997).
VR can be defined as a dynamic and reactive
composition with the environment created by a
computer and used for different purposes of human
interaction (Choi et al. 2005). Banos (2005) con-
siders VR as a human experience, giving emphasis to
the individual who uses the technology, and defines
it as an advanced communication interface that
allows the user to experiment ‘‘other realities’’.
This communication interface refers to the relation-
ship between the individual’s motor-sensorial chan-
nels and the virtual environment created by the
physical computer components and its information
(Riva et al. 2002b). Steuer (1992) defines it as a real
or simulated environment in which a participant
experiences telepresence, that is, an individual
experiences presence in an environment by means
of a communication medium.
Wiederhold and Rizzo (2005) claim that VR offers
the potential to create systematic human testing,
training and treatment environments that allow for
the precise control of complex, immersive, and
dynamic three-dimensional stimulus presentations,
within which sophisticated interaction, behavioural
tracking and performance recording is possible.
The essential point of these definitions is to allow
the individual to act, that is, that he may interact and
modify the virtual environment in which he is
sensorially inserted. The individual does not remain
passive in relation to the images and to other
available sensorial elements, he is not limited to
merely observing, he changes the environment and
can be changed by it as well as receive information
through interaction.
According to Riva et al. (2002a), clinical psychol-
ogy can greatly benefit from VR through the
important role that memory and imagination play
in psychotherapy. For many years, mental images
have been used by psychology in therapeutic pro-
cesses. In anxiety disorders, we know that anxiogenic
mental images are responsible for maintaining fear,
worry or discomfort, triggering dysfunctional
thoughts, disadaptive behaviour and negative feel-
ings. Furthermore, they are capable of triggering
physiological reactions similar to those caused by
anxiogenic environmental stimuli (Riva et al.
2002a).
In addition, it is considered that experiences of
imagination and perception may be difficult to
distinguish, not just from neurophysiological aspects
(both processes have a common location in the
brain) but also from experimental and qualitative
aspects (the difficulty in distinguishing between real
life experiences and scenes created by the imagina-
tion) (Riva et al. 2002a), what can make the use of
VR even more interesting for treatment purposes.
The use of VR as an advanced system of images is
an experience that can diminish the gap between the
imagination and the real world and it can improve
the psychotherapeutic efficacy because of its ap-
proach. Mental images can be very useful in clinical
practice: the modification, habituation and substitu-
tion of non-adaptive images are effective means of
psychological treatment. The use of VR as an
‘‘advanced imaginal system’’ is also capable of
furnishing a perceptual illusion of non-mediation,
Virtual reality and exposure therapy 221
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that is, the individual no longer perceives the
existence of a medium in his communication envir-
onment and begins to react as if it did not exist. The
difference between virtual environment and reality
disappears (Riva et al. 2002a).
This illusion of non-mediation is an integral part
of an essential aspect of the study of VR as a
psychotherapeutic tool. It refers to the concept of
presence and, more importantly, to its practical
application. In short, presence is to feel more a
part of the virtual environment than of the real
environment in which one is physically located.
Presence is enhanced when the user is more involved
in activities or has tasks to carry out (Coelho et al.
2006). It depends on the degree of interaction and
interactivity present in both the real environment
and the virtual environment (Sastry and Boyd
1998).
In order to experience presence, two factors are of
the essence: involvement and immersion (Witmer
and Singer 1998) Involvement is a subjective psy-
chological state experienced as a consequence of
focusing one’s energy and attention on a set of
stimuli. Moreover, the level of involvement within an
environment depends on the level of intrinsic
motivation to perform an activity. On the other
hand, immersion has to do with the psychological
state characterized as perceiving oneself involved,
included and interacting with an environment that
offers a continuous flow of stimuli and experiences.
VR integrates real-time computer graphics, body
tracking devices, audio/visual/touch displays, and
other sensory input devices to immerse patients in
a computer-generated virtual environment (Wieder-
hold and Rizzo 2005; Krijn et al. 2007). Already,
much research has been aimed at finding out what
factors can contribute to a sense of presence in
virtual environments. It is believed that the more
inclusive, extensive, surrounding and vivid the
virtual environment, the higher the sense of presence
(Banos et al. 2004). Banos et al. (2004) approached
presence as being determined by media character-
istics and user characteristics. Presence in a virtual
environment relates directly to the reproduction of
physical characteristics of reality. Auditory and
tactile stimuli can be added in order to increase
immersion in the environment (Emmelkamp 2005).
However, feeling the virtual space and ‘‘really’’ being
immersed in it depend more on the means of
locomotion and action than on other sensorial
stimuli and the quality of the image (Sastry and
Boyd 1998). Witmer and Singer (1998) developed a
widely accepted set of presence causal factors that
include measures of control, sensory, distraction,
and realism factors. Presence is usually enhanced
when the user can exert a greater level of control
over the task environment or has an increased ability
to interact in the environment (Tichon and Banks
2006).
It is also important to add to these stimuli the
need to create and share the cultural network that
furnishes meaning and visibility to the population
and the objects that inhabit the virtual environment.
Riva et al. (2002b) suggest four fundamental points
when creating presence: recognizing the character-
istic of mediation in any presence experience; always
think of the experience as immersed in a social
context; reproduce the ambiguity inherent to daily
situations and emphasize the cultural role.
Despite the efforts to increase the sense of
presence, patients exposed to virtual environments
do not always feel immediately immersed or present.
Some patients require some sessions (two or three)
in order to reach this result, whereas other respond
by feeling immersed in the virtual environment as
soon as they have their first contact with it (Wieder-
hold and Wiederhold 2000). Another concern is
about motion sickness, which is influenced by image
lag or the responsiveness of displayed image to head
motion (Bush 2008). Another point is that presence
is highly individualistic, what means that it is out of
therapist’s full control. Bush (2008) points out that
the patient’s readiness for change can also influence
the results of presence, and affirms that ‘‘with
motivation comes receptivity, and with receptivity
comes presence’’ (Bush 2008, p. 1037). Research
into these individual differences that can moderate
presence is needed because it may enhance selecting
patients who profit most from treatment by means of
VR exposure therapy (Krijn et al. 2004b).
The measurements of causal factors of presence
generally rely on self-report. In utilizing any self-
report measure of presence, one must consider that
results can be tied to the personal aspects of the user
(Tichon and Banks 2006). Objective measures must
also be used.
Presence is considered to be a presumed factor
that enables anxiety to be felt during VR exposure.
Theoretical literature posits that the greater the
presence, the better the response to therapy and
the better the results in the treatment and prolonged
positive effects (Wiederhold and Wiederhold 2000).
Otherwise, empirical studies on the relation between
presence and anxiety have been inconclusive. Some
studies have found a linear relationship between
presence and experienced anxiety (Regenbrecht et
al. 1998; Robillard et al. 2003). Other studies
reported no relation between presence and anxiety
(Krijn et al. 2004a,b; Slater 2004). The fact is that
these studies present some methodological limita-
tions, like lack of psychometric instruments or small
samples. One study with 37 participants measured
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presence in a virtual environment for fear of heights
with a self-report questionnaire. Results have shown
that fear increased with higher presence (Regen-
brecht et al. 1998). Robbilard et al. (2003) studied
the relationship between presence and anxiety within
13 phobic participants and 13 non-phobic control
participants with one item self report ratings by
exposing them to phobogenic stimuli in therapeutic
virtual environments derived from computer games.
The results pointed to a positive relationship.
Otherwise, Krijn et al. (2004a) investigated feelings
of presence by a questionnaire in VR exposure
therapy in patients with acrophobia using either a
head-mounted display (HMD) or a computer auto-
matic virtual environment (CAVE) and found no
differences in effectiveness between both conditions
and no relationship was found between presence and
anxiety in treatment completers.
Two recent studies on the topic reported positive
relationship between presence and anxiety but not
on all measures, confirming the inconstant results on
the issue. Bouchard et al. (2008) conducted a study
with a sample of 31 adults suffering from snake
phobia. Measures of presence occurred in three
conditions: a baseline control immersion, an immer-
sion in an anxiety-inducing environment, and an
immersion in a non-threatening environment that
should not induce anxiety. Presence ratings were
higher in the anxious immersion than in the baseline
or the non-anxious immersion. However, presence
questionnaire did not corroborate this finding,
where scores varied significantly in the opposite
direction. Another VR study of 36 participants
with flying as the predominantly feared stimulus
reported relation between self-reported presence and
in-session anxiety. Presence was measured by a
questionnaire. The authors also found that presence
served as a mediator of the relation between
pretreatment anxiety and in-session anxiety. They
conclude that this finding suggest that presence
functions as the conduit that enabled phobic anxiety
to be felt during exposure, and implied that a sense
of presence may have been necessary to experience
anxiety during exposure to a virtual environment
(Price and Anderson 2007). One last result sug-
gested that presence was not directly related to
treatment outcome, what suggests that the sense of
presence during VR exposure may be necessary but
not sufficient to achieve benefit from this kind of
exposure technique (Price and Anderson 2007).
One concept that is different but complementary
to presence is an experimental element that is
important when creating virtual environments: rea-
lity judgment. In an article that underlines the
importance of reality judgement in virtual environ-
ments and differentiates it from the concept of
presence, Banos et al. (2000) question the way in
which people decide what is real. The answer to this
questioning can lead to important guidelines in the
creation of virtual environments. The author uses
Brinkman’s explanation (Banos et al. 2000) to clarify
this concept of reality judgment, stating that an
experience is considered real when it holds internal
and external correspondence. Internal correspon-
dence refers to correspondence of behaviours with
feelings. According to a definition by Witmer and
Singer (1998), it has to do with the involvement that
presence raises. The above-mentioned author (Wit-
mer and Singer 1998) also state that external
correspondence occurs when a behaviour corre-
sponds to its consequences, making it more con-
nected to immersion.
Traditional exposure treatments: In vivo and imaginal
exposures
Cognitive-behavioural therapy is the most studied
psychotherapeutic modality in panic disorder (PD)
and has demonstrated, in the most different experi-
mental studies, to be sufficiently effective (Clum et
al. 1993; Gould et al. 1995; Haby et al. 2006).
Exposure is an extremely important behavioural
technique, especially in the treatment of agoraphobic
avoidance.
Exposures are therapeutical proceedings in which
the client is exposed to anxiogenic stimuli (internal
or external) in order to cause habituation and
extinction of anxious and agoraphobic responses.
There are different kinds of exposure such as in vivo
and imaginal. In vivo exposure aims at strengthening
the self-efficacy of patients through hierarchal ex-
posures (gradual) to feared situations or situations
that are avoided, in a prolonged way, aiming at
reducing anxiety when confronted with the anxio-
genic stimulus. Imaginal exposures aim at the same
goal through the elaboration of mental images that
contain the stimuli that patients consider to be
anxiogenic.
Virtual exposures
Studies that demonstrate the utility of VR in the
treatment of psychological disorders are increasing,
mainly in the field of anxiety disorders (Botella et al.
2004). Case histories, open comparative studies,
randomized controlled trials and reviews of literature
that support the potential of this therapy provide
evidence that VR exposure therapy is an effective
technique and a promising tool for the treatment of
several anxiety disorders (North et al. 1997; Pull
2005; Gorini and Riva 2008). With regard to the
treatment of panic disorder and agoraphobia, VR
Virtual reality and exposure therapy 223
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can help to overcome some of the limitations of
standard exposure therapy, one of the main ther-
apeutic components to treat this disorder (Botella
et al. 2004).
Riva (2005) describes VR as a medium that is as
effective as reality in inducing emotional responses.
This is because VR software can be created so that
virtual environments reproduce anxiogenic situa-
tions very similar to reality and they can be used as
scenarios for exposure in the treatment of different
psychiatric disorders. They are capable of generating
stimuli of greater magnitude than other techniques
already in existence (Andrews 2005). As is the case
in in vivo and imaginal exposure, it is possible to
create a list of the most feared situations and stimuli
that correspond to reality together with the patient.
The feared stimuli are integrated in virtual environ-
ments that permit interaction, allowing the user to
act in these scenarios as he would in a real environ-
ment (Maltby et al. 2002). The sense of presence
that the virtual environments allow one to experi-
ment and the motor-sensorial involvement (resulting
from different sensorial stimuli and the use of
position trackers) offer a sense of real and vivid
immersion, greater than that which one would feel in
building scenarios from one’s imagination alone
(Vincelli et al. 2003).
Virtual exposure therapy is supposed to work
according emotion-processing model (Parsons and
Rizzo 2008). By activation of the fear network
through confrontation with threatening stimuli
(which elicits the fearful responses) new and in-
compatible information must be added into the
emotional network (Foa and Kozak 1986). The
processes of habituation and extinction aid modifi-
cation of the fear structure, making its meaning less
threatening. VR exposure has been proposed as a
new medium for exposure therapy for being capable
of activating the fear structure and modifying it
(Rothbaum and Hodges 1999).
Virtual exposure can be an alternative for imaginal
exposure and a useful intermediate step for those
patients who find the idea of confronting agorapho-
bic situations too aversive and refuse in vivo ex-
posure. Receiving a virtual exposure treatment can
increase patients‘ possibilities of accepting an in vivo
exposure program in the future (Botella et al. 2004).
The use of virtual environments aimed at expo-
sure treatment is very efficacious when compared to
the results of imaginal exposure (Maltby et al. 2002).
Wiederhold et al. (2002a) conducted a study about
fear of flying to measure the effectiveness of VR
exposure versus imaginal exposure therapy. Thirty
participants with specific phobia fear of flying were
randomly assigned to one of three groups: systematic
desensitization with imaginal exposure therapy, VR
exposure with no physiological feedback, or VR
exposure with physiological feedback. The results
demonstrated that only one participant (of ten
participants) of the first group, eight of the ten
participants of the second group, and ten out of the
ten participants of the third group reported an ability
to fly without medication or alcohol at 3-month
follow-up. Although the small sample size, VR
exposure was more effective than systematic desen-
sitization with imaginal exposure therapy. Wieder-
hold and Wiederhold (2000) compiled the results of
600 VR sessions and described some data about
imaginal exposure compared to VR exposure. Pa-
tients of three groups (scoring low, medium and high
in absorption and hypnotizability measures) had
better treatment outcomes in VR therapy than in
imaginal therapy. The authors also cited an unpub-
lished study comparing VR exposure therapy to
imaginal exposure therapy for the treatment of fear
of flying in which patients in the VR exposure group
experienced much higher Subjective Units of Dis-
tress Scale (SUDS) ratings during initial exposure
sessions, with a subsequent drop in ratings during
later sessions; whereas imaginal exposure group had
lower SUDS ratings during initial exposure sessions,
with a slight rise in ratings during session four and a
drop again in sessions five and six. The authors
conclude that participants were not able to feel the
anxiety as strongly, therefore may not have been able
to fully activate fear structure.
We know that in order for habituation to occur
more effectively it is necessary that the patient feel
activation both in an objective way (anxiety mea-
sured by objective instruments like physiological
measures) as well as in a subjective way (the patient
himself reports anxiety). This is what is meant by the
concept of synchrony that occurs when the objective
and subjective measures take place together during
the treatment, although it is more likely to occur in
activities resulting from great anxiogenic activation
(Wiederhold and Wiederhold 2003). It may be that
in imaginal exposure, immersion in imaginary sce-
narios open to objective and subjective activation
may not occur since the patients may find it easier to
cognitively avoid exposure to the scenarios, thus
reducing the anxiety they feel and making it harder
for habituation to take place (Wiederhold and
Wiederhold 2000). Furthermore, exposure
mediated by VR offers greater change in self-efficacy
than imaginal exposure, since virtual environments
increase the possibility the patient has of successfully
handling highly anxiogenic situations (as can be seen
in relation to in vivo exposure) (Riva and Wieder-
hold 2002).
As opposed to imaginary scenarios, in virtual
scenarios the scenes to be exposed are created
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from concrete stimuli that allow emotional involve-
ment, thus increasing the probability of extinguish-
ing a fearful response (Maltby et al. 2002). VR
allows a higher immersion in the situations, given
that several sensorial modalities can be triggered at
the same time (e.g., audio, visual, interoceptive)
(Botella et al. 2004). This possibility is an alternative
for patients who find it difficult to imagine evocative
anxiety scenes or to go on imagining such scenes
(Wiederhold and Wiederhold 2003).
Aside from this, exposure to VR environments
allows a gap to be filled: the patient can expose
himself to anxiogenic stimuli in a vivid way, as if the
stimuli were real whenever in vivo exposure is not
possible or when the anxiety brought on by the real
situation is extreme, making it hard for the patient to
enter or remain in an exposed situation and, thus,
also reducing the chances of the patient abandoning
treatment (Jang et al. 2000; Cardenas et al. 2006).
An important advantage of virtual exposure ther-
apy for the treatment of panic disorder and agor-
aphobia is the possibility that the virtual program
offers of situational and interoceptive exposure at the
same time. Several body sensations with sound and
optical effects � like breathing difficulties, increasing
heart rate, tunnel vision, blurred vision � can be
introduced in the virtual environment in order to
achieve a higher activation of the anxiety response
during the virtual exposure to agoraphobic situations
(Botella et al. 2004).
Another important aspect is that the exposures
can be carried out in the therapist’s office. This is
more convenient (it is easier to create adequate
situations than to look for them in real life and also
to create exposure to situations that seldom occur in
real life) and controlled (the intensity of the stimuli
that cause anxiety is chosen by the patient and
therapist, bearing in mind the pre-established hier-
archy, reducing the possibility of unwanted sur-
prises); it guarantees initial security during
exposure to stimuli that are felt like very anxiogenic;
it helps the patient reduce the fear of losing control
in public during the exposure tasks and also to avoid
that other people know about his/her problem
(Botella et al. 2004; Cardenas et al. 2006).
Aside from providing the initial security needed
for in vivo exposure, as was mentioned above, VR
can also be used in other moments of the treatment,
such as during crises, to help the patient overcome
the moment and carry on with the treatment
(Andrews, 2005).
The patient’s focal concerns can also be isolated
and approached in a more effective way in virtual
environments (Maltby et al. 2002; Choi et al. 2005).
Due to the sense of security it offers, the virtual
scenario can also bring about the expression of
thoughts and feelings that in real situations would
be difficult to be approached, and in so doing, it can
also strengthen the therapist�patient relationship
(Riva, 2005).
An important feature of VR software is the
flexibility it offers in creating virtual environments.
Some software already enable users to manipulate a
large number of stimuli, structuring the environment
according to the needs of the patient as well as
monitoring the user’s responses while interacting
with the virtual scenario. These possibilities enhance
the therapeutic effectiveness of virtual exposure
treatment (Vincelli et al. 2003).
The individual responses to the virtual environ-
ments vary according to the specific needs of each
patient (Wiederhold and Wiederhold, 2000).
Therein lies the importance of the above-mentioned
flexibility in virtual environments so that the mod-
ifications that prove necessary to meet the singular
needs of each case be taken into account. Moreover,
the psychotherapist’s ability and knowledge are also
put to test as he or she must also have the adequate
resources to evaluate the patient’s specific needs, to
decide how these needs can be inserted in the
reconstruction of the virtual environments and,
also, select the contents of the interventions neces-
sary at the moment of exposure. In the latter case,
Wiederhold and Wiederhold (2000) collected inter-
esting data on the different forms of intervention by
the psychotherapist that is required by the patients.
They concluded that depending on the kind of
phobia in reference, the patient exposed to the
virtual environment would require different partici-
pation by the psychotherapist. Patients who were
afraid of flying preferred not to be interrupted by the
therapist when questioned about their level of
anxiety; patients with social anxiety felt more cap-
able of verbalizing during exposure and also per-
ceived themselves as taking part of the virtual
scenario more often.
The therapeutic alliance is an important compo-
nent of psychotherapy in conjunction with VR as is
also the case in any other kind of psychotherapy.
Nonetheless, according to Cardenas et al. (2006)
some authors still consider this aspect a weak point
in exposure therapy that makes use of VR. However,
the authors (Cardenas et al. 2006) also point out
studies that demonstrate the contrary, how this can
be a defining element. One of them demonstrates
that both traditional psychotherapy and psychother-
apy complemented by new technology can be
satisfactory and also point out that there is greater
acceptance of VR therapy when compared to in-
dividual therapy.
VR exposure therapy showed a large mean effect
size compared to inactive (waiting list and attention
Virtual reality and exposure therapy 225
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control) and active (relaxation and bibliotherapy)
control conditions. This result was consistent across
secondary outcome categories: domain-specific,
general subjective distress, cognition, behaviour,
and psychophysiology (Powers and Emmelkamp
2008). Gregg and Tarrier (2007) examined 17 VR
controlled trials and all of them report VR-based
approached to be superior to no treatment and at
least as effective as in vivo exposure or other
alternative treatment approaches. Treatment gains
demonstrated that VR environments were capable of
evoking the anxiety responses necessary for exposure
to be effective (Gregg and Tarrier 2007).
According to Cote and Bouchard (2005)Cote and
Bouchard (2005a) large number of outcome studies
have significantly contributed to support the efficacy
of VR exposure and some randomized control trials
converge towards the conclusion that VR exposure is
as effective as in vivo exposure. One representative
study of these results is a large sample controlled
trial of fear of flying treatment. When comparing VR
exposure to in vivo exposure therapy no significant
differences between these two conditions were found
and treatment gains were maintained at 6- and 12-
month follow-up assessments, with both exposure
treatments leading to equivalent improvement
(Rothbaum et al. 2006).
However, few studies have looked in detail at this
efficacy and questions on how effective VR exposure
is, if it has a strong enough impact to affect cognitive
processes and about objective outcome assessments
still remain unanswered (Cote and Bouchard 2005).
In a recent meta-analysis, Powers and Emmelkamp
(2008) verified that there was a small effect size
favouring VR exposure therapy over in vivo condi-
tions. According to the authors, several explanations
are possible for the slightly superiority of VR
exposure over in vivo exposure. Some of them are:
credibility and expectancy may have been higher for
VR exposure conditions when compared to in vivo
exposure, patients may have progressed through
their hierarchy more rapidly in the VR exposure
due to a perception of increased control and safety
and exposures could be more personally tailored by
the experimenter in the VR exposure conditions.
Physiological measures during virtual exposure
In psychotherapy that makes use of VR it is
important that the patients experiment physiological
changes and phobic anxiety similar to what they feel
in real life situations (Jang et al. 2002). Even people
who are not phobic present some sort of physiolo-
gical activation when exposed to a virtual environ-
ment for the first time but their physiology stabilizes
in approximately 20 min on average (Wiederhold
and Wiederhold 2000; Moore et al. 2002).
In exposure to virtual environments, phobic
patients respond quite differently from non-phobic
subjects. However, this difference tends to decrease
with habituation (Wiederhold et al. 2002b). Physiol-
ogy is a means of evaluating the results of the
treatment mediated by VR.
Few studies measure physiological responses to
virtual exposure’s environments, although the addi-
tion of objective measures of arousal and informa-
tion processing mechanisms would be a valuable
contribution in order to validate the usefulness of
VR in the treatment of anxiety disorders (Cote and
Bouchard 2005). Objective physiological measures
of anxiety have not been established well enough
with regard to VR exposure treatments. Most of the
studies conducted to date rely on the individual’s
subjective self-reports to assess levels of anxiety
experienced during virtual exposure (Krijn et al.
2004b; Wilhelm et al. 2005). According to Wilhelm
et al. (2005), physiological monitoring seems to hold
clear promises to help objectively evaluate virtual
exposure outcomes and to enhance the understand-
ing of the underlying mechanisms. Initial findings
indicate that heart rate responses during VR ex-
posure treatments are minimal or nonexistent, even
when patients report high levels of fear. It’s an
interesting finding, as heart rate has repeatedly
been the most potent physiological anxiety measure
in real-life exposure studies with individuals suffer-
ing from specific phobias of the situational type
(Nesse et al. 1985; Roth et al. 1986; Wilhelm and
Roth 1998; Wilhelm et al. 2005) and is believed to
be an important indicator of emotional processing
during exposure therapy (Wilhelm et al. 2005). The
lack of heart rate activation during VR exposure
might further be associated with VR-specific effects,
such as the influences of visual attention or immer-
sion. Focusing one’s attention on a virtual environ-
ment might result in physiological changes that are
specifically related to visual attention, and which
differ from physiological responses to a real environ-
ment. On the other hand, electrodermal activity in
VR exposure seems to clearly distinguish phobic
from non-phobic individuals (Wilhelm et al. 2005).
In a study carried out by Wiederhold et al.
(2002b), they observed that participants and pa-
tients with a 2-year follow-up did not present a
change in their periphery skin temperature. The
heart rate also did not reveal significant variations
except in patients that suffered panic attacks during
exposure. The change in breathing rhythm was also
small. The only measure that showed significant
alterations was skin conductance. The physiological
responses observed occurred more rapidly when the
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visual stimulus was shown and also during treatment
while the desensitization process took place. Other-
wise, Meehan et al. (2005), measuring presence in a
stressful environment, found that heart rate consis-
tently differentiated among conditions with more
sensitivity and more statistical power than the other
physiological measures, and more than most of the
self-reported measures. The authors also found
some support for skin conductance.
Some electroencephalographic measures are
found in literature about VR, but these studies are
still on initial investigation, not yet pointing out
conclusive findings that could help in treatment
improvement (Othmer and Kaiser 2000).
Studies of PD treatment with VR
Jang et al. (2000) submitted subjects diagnosed with
agoraphobia to virtual exposure treatment that
included training in relaxation in ten different
scenarios in order to check its efficacy. Immediately
after they began taking part in the VR sessions, the
subjects reported physical changes such as perspira-
tion and palpitation. During exposure, physiological
changes were not reported nor was there an increase
in the SUDS ratings. Most of the participants were
not able to feel immersed in the virtual environments
and the exposures were suspended after the second
session. The authors (Jang et al. 2000) pointed to
some factors as possible variables that may have
influenced in a negative fashion the immersion of the
subjects in the virtual scenarios, such as, for in-
stance: time (20 min) of use of the HMD that made
the participants feel uncomfortable and its field of
vision of 508 made immersion harder; the contin-
uous presence of the therapist alongside the subject
throughout exposure; the light that allowed viewing
through the opening in the headgear; the discomfort
caused by the sensors placed on the body in order to
measure physiological data and the undetermined
limits of the therapist’s verbalizations.
In an randomized study in which three groups
were compared (control, cognitive-behaviour ther-
apy with virtual exposure and just cognitive-beha-
viour therapy;Vincelli et al. 2003), it was shown that
in the two groups undergoing treatment there was a
significant decrease of panic attacks, depression
level, state and trait anxiety. The difference was
observed during the time it took to reach these
results: the group that underwent treatment with
virtual exposure reached these results in only eight
sessions, whereas the other treatment group was
submitted to 12 sessions. This study did not include
a follow-up assessment.
Choi et al. (2005), in a randomized study, tested
the efficacy of a treatment for PD with agoraphobia
comparing four-session virtual exposure to 12-ses-
sion cognitive behavioural therapy (Panic Control
Program). Treatment effects were measured with
self-report questionnaires, including the BDI, STAI,
ASI, PBQ, ACQ, and BSQ. Although both groups
improved quite significantly after treatment, long-
term efficacy was greater in the group that did not
undergo virtual exposure in the treatment protocol.
Another important finding was that cognitive-beha-
vioural therapy was more effective in changing the
measures related to the cognitive evaluation of
anxiety, whereas the treatment with virtual expo-
sures distinguished itself in the handling of trait
anxiety. High end-state functioning, including the
success rate of stopping or reducing medication at
post-treatment and 6-month follow-up was also
measured. There were no significant differences
between the two treatment groups in high end-state
functioning and medication discontinuation at post-
treatment, but there was a significant difference in
medication discontinuation at 6-month follow-up. In
the 12-session cognitive behavioural therapy group
the number of subjects who could discontinue their
medication was gradually increased when compared
to the other group.
Martin et al. (2007) conducted a case study about
the use of VR exposure for the treatment of PD with
agoraphobia. The patient was a 26-year-old Cauca-
sian woman. The utilized clinical measures were
categorized into target behaviours, panic and agor-
aphobia measures, global functioning, and general
psychopathology measures. The patient was not
instructed to carry out in vivo exposure tasks
between treatment sessions. A reduction in the
clinical measures occurred at short term. Three-,
6- and 12-month follow-up assessments were con-
ducted and long-term therapeutic gains were main-
tained. The patient did not receive any other
psychological treatment during the follow-up period.
VR exposure showed to be efficacious for the
treatment of PD with agoraphobia in that patient.
The goals achieved in the virtual environment were
generalized to real agoraphobic situations and to
other real situations not treated.
Discussion
The potentialities that VR brings to exposure treat-
ment are significant and one of its biggest advantages
is the great patient acceptability. Garcia-Palacios
et al. (2001) show that 80% of the participants of
their study preferred virtual exposure to in vivo
exposure. Perhaps this result reflects some kind of
avoidance of real stimuli. However, it is better that
the patient first consider virtual exposure as a kind of
Virtual reality and exposure therapy 227
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treatment so that it can prepare the patient for future
in vivo exposures.
Nevertheless, despite the advantages of applying
VR, the use of this technology has several limita-
tions. Some patients have objected to VR?s visual
stimuli or have complained of drowsiness during
virtual exposure (Wiederhold and Wiederhold
2000). Some patients have felt nauseated, which
may lead to them to abandoning the treatment
(Maltby et al. 2002).
Also to be considered are the limitations imposed
by the software that is often restricted to the protocol
that was created. Due to this, requirements that have
not been included in the program cannot be easily
provided, which may impede virtual environments
from meeting the specific needs of each patient.
Botella et al. (2004) states that in some softwares
used in studies of VR exposure for treating PD with
agoraphobia the possibility of introducing modula-
tors is limited and the manipulations have to be
performed before entering the scenario. It is not
possible to introduce changes during the exposure
tasks. In designing the software, the main character-
istics of PD with agoraphobia (situational and
interoceptive avoidance), as well as some important
anxiety modulators (the number of people, conver-
sations and instructions with threatening contents,
the length and duration of the trips) have to be
considered (Botella et al. 2004).
Another important point is that only few research-
ers have included a behavioural avoidance test
(BAT) in their studies. Follow-up results are gen-
erally based on self-report rather than on formal
behavioural tests. It is necessary to measure whether
or not the effects of VRET generalize to the world
outside the laboratory (Krijin et al. 2004).
The lack of standardized protocols is also a flaw in
this kind of treatment and points to the need for
further research to enable the elaboration of these
very same protocols. Protocol publication is of vital
importance in order to reduce costs and time,
sharing the weak and strong points of each research
work, and thus avoid the elaboration of treatments
through trial and error (Andrews 2005).
According to Jang et al. (2000), the closeness
between therapist and patient may hinder immer-
sion. Particularly during a moment of great anxiety,
the therapist’s presence may reassure the patient and
this could interfere with the process of habituation.
Krijn et al. (2007) observed that, to date, no
research has been done in which VR exposure
therapy is compared to VR exposure therapy plus
pure cognitive techniques used during sessions of
exposure. The authors claim that there is a clear
need for more detailed analysis of the role of
cognitive techniques in VR exposure. In addition,
in most studies of VR effectiveness, VR is not
focused as a single therapeutic mode, being em-
bedded in a multimodal intervention, which makes it
difficult to conclude on the effects of VR as a
therapeutic method (Krijin et al. 2004).
There is little research about long-term effective-
ness of VR treatments. Long-term follow-ups are
required to draw better conclusions about the efficacy
of VR in the therapeutic situation (Gregg and Tarrier
2007). Studies comparing VR exposure to in vivo
exposure and to imaginal exposure are also required
in order to increase acceptance of VR treatment.
Riva and Wiederhold (2002) point out the need
for further controlled studies in the field of VR that
will demonstrate its clinical and economic advan-
tages, despite the clinical rationale behind the use of
VR being currently clear. Over the last 10 years VR
systems have become less costly, more available and
generally more usable (Parsons and Rizzo 2008). In
Brazil, this kind of technology is far from being fully
accessible to people because of the cost of the
necessary equipment and the building of the virtual
environments.
Conclusion
The use of VR in the treatment of PD has led to
positive results. VR exposure therapy should be used
to overleap imaginal exposure limitations and strong
avoidance of in vivo exposure. However, despite new
developments, a large portion of VR?s potential is
still unexplored. It is important that new virtual
environments be created so that controlled investi-
gations of its clinical application can be carried out.
It is also essential that they be divulged in order to
contribute towards the improvement of the environ-
ments and the speed in which they take place, thus
avoiding that several researchers make similar at-
tempts and mistakes whilst developing their work. In
the process of creation and investigation, it is very
important that the clinical experiences carried out in
virtual environments be related to real experiences,
within a flexible context that combines cultural,
physical and cognitive aspects and in so doing, reach
a high degree of sense of presence and reality
judgment.
Acknowledgements
Supported by the Brazilian Council for Scientific
and Technological Development (CNPq), Grant
554411/2005-9.
Statement of interest
No conflict of interest to report.
228 M.R. de Carvalho et al.
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References
Andrews T. 2005. Commentary on Riva G, Virtual reality in
psychotherapy: Review. Cyberpsychol Behav 8(3):231�232.
Banos RM. 2005. Commentary on Riva G, Virtual reality in
psychotherapy: Review. Cyberpsychol Behav 8(3):232�233.
Banos RM, Botella C, Garcia-Palacios A, Villa H, Perpina C,
Alcaniz M. 2000. Presence and reality judgment in virtual
environments: A unitary construct? Cyberpsychol Behav
3(3):327�335.
Banos RM, Botella C, Alcaniz M, Liano V, Guerrero B, Rey B.
2004. Immersion and emotion: their impact on the sense of
presence. Cyberpsychol Behav 7:734�740.
Baumgartner T, Valko L, Esslen M, Jancke L. 2006. Neural
correlate of spatial presence in an arousing and noninteractive
virtual reality: An EEG and psychophysiology study. Cyberp-
sychol Behav 9(1):30�45.
Botella C, Villa H, Banos R, Perpina C, Garcıa-Palacios A. 1999.
The treatment of claustrophobia with virtual reality: Changes
in other phobic behaviors not specifically treated. Cyberpsychol
Behav 2:143�148.
Botella C, Banos RM, Villa H, Perpina C, Garcıa-Palacios A.
2000. Virtual reality in the treatment of claustrophobic fear: A
controlled, multiple-baseline design. Behav Ther 31:583�595.
Botella C, Villa H, Garcia-Palacios A, Banos RM, Perpina C,
Alcaniz M. 2004. Clinically significant virtual environments for
the treatment of panic disorder and agoraphobia. Cyberpsychol
Behav 7(5):527�535.
Bouchard S, St-Jacques J, Robillard G, Renaud P. 2008. Anxiety
increases the feeling of presence in virtual reality. Presence
17(4):376�391.
Bush J. 2008. Viability of virtual reality exposure therapy as a
treatment alternative. Comput Hum Behav 24:1032�1040.
Cardenas G, Munoz S, Gonzalez M, Uribarren G. 2006. Virtual
reality applications to agoraphobia: A protocol. Cyberpsychol
Behav 9(2):248�250.
Castelnuovo G, Gaggioli A, Mantovani F, Riva G. 2003. From
Psychotherapy to e-therapy: The integration of traditional
techniques and new communication tools in clinical settings.
Cyberpsychol Behav 6(4):375�382.
Choi Y, Vincelli F, Riva G, Wiederhold BK, Lee J, Park K. 2005.
Effects of group experiential cognitive therapy for the treatment
of panic disorder with agoraphobia. Cyberpsychol Behav
8(4):387�393.
Clum GA, Clum GA, Surls R. 1993. A meta-analysis for panic
disorder. J Consult Clin Psychol 61:317�326.
Coelho CM, Santos JA, Silverio J, Silva CF. 2006. Virtual Reality
and Acrophobia: One-Year Follow-Up and Case Study. Cy-
berpsychol Behav 9(3):336�341.
Cote S, Bouchard S. 2005. Documenting the efficacy of virtual
reality exposure with psychophysiological and information
processing measures. Appl Psychophysiol Biofeedback
30(3):217�232.
Emmelkamp PM, Bruynzeel M, Drost L, van der Mast CA. 2001.
Virtual reality treatment in acrophobia: A comparison with
exposure in vivo. Cyberpsychol Behav 4:335�339.
Emmelkamp PM, Krijn M, Hulsbosch AM, de Vries S, Schuemie
MJ, van der Mast CA. 2002. Virtual reality treatment versus
exposure in vivo: a comparative evaluation in acrophobia.
Behav Res Ther 40:509�516.
Emmelkamp PMG. 2005. Commentary on Riva G, Virtual reality
in psychotherapy: review. Cyberpsychol Behav 8(3):235�237.
Foa EB, Kozak MJ. 1986. Emotional processing of fear: Exposure
to corrective information. Psychol Bull 99:20�35.
Garcia-Palacios A, Hoffman HG, See SK, Tsai A, Botella C.
2001. Redefining therapeutic success with virtual reality
exposure therapy. Cyberpsychol Behav 4:341�348.
Garcia-Palacios A, Hoffman H, Carlin A, Furness TA 3rd, Botella
C. 2002. Virtual reality in the treatment of spider phobia: a
controlled study. Behav Res Ther 40:983�993.
Glantz K, Rizzo AK, Graap K. 2003. Virtual Reality for
Psychotherapy: Current reality and future possibilities. Psy-
chotherapy 40(1/2):55�67.
Gorini A, Riva G. 2008. Virtual reality in anxiety disorders: the
past and the future. Expert Rev Neurother 8(2):215�233.
Gould R, Otto MW, Pollack MH. 1995. A meta-analysis of
treatment outcome for panic disorder. Clin Psychol Rev
15(8):819�844.
Gregg L, Tarrier N. 2007. Virtual reality in mental health. A
review of the literature. Soc Psychiatry Psychiatr Epidemiol
42:343�354.
Haby MM, Donnelly M, Corry J, Vos T. 2006. Cognitive
behavioural therapy for depression, panic disorder and general-
ized anxiety disorder: a meta-regression of factors that may
predict outcome. Aust NZ J Psychiatry 40:9�19.
Jang DP, Ku JH, Shin MB, Choi YH, Kim SI. 2000. Objective
validation of the effectiveness of virtual reality psychotherapy.
Cyberpsychol Behav 3(3):369�74.
Jang DP, Ku JH, Choi YH, Wiederhold BK, Nam SW, Kim IY,
Kim SI. 2002. The development of virtual reality therapy
(VRT) system for the treatment of acrophobia and therapeutic
case. IEEE Trans Inf Technol Biomed 6(3):213�217.
Klinger E, Bouchard S, Legeron P, Roy S, Lauer F, Chemin I,
et al. 2005. Virtual reality therapy versus cognitive behavior
therapy for social phobia: A preliminary controlled study.
Cyberpsychol Behav 8(1):76�88.
Krijn M, Emmelkamp PMG, Biemond R, de Wilde de Ligny C,
Schuemie MJ, van der Mast CAPG. 2004a. Treatment of
acrophobia in virtual reality: the role of immersion and
presence. Behav Res Ther 42(2):229�239.
Krijn M, Emmelkamp PM, Olafsson RP, Biemond R. 2004b.
Virtual reality exposure therapy of anxiety disorders: a review.
Clin Psychol Rev 24(3):259�281.
Krijn M, Emmelkamp PMG, .Olafsson RP, Schuemie M J, Van
Der Mast CAPG. 2007. Do self-statements enhance the
effectiveness of virtual reality exposure therapy? A comparative
evaluation in acrophobia. Cyberpsychol Behav 10(3):362�370.
Maltby N, Kirsch I, Mayers M, Allen GJ. 2002. Virtual reality
exposure therapy for the treatment of fear of flying: A
controlled investigation. J Consult Clin Psychol 70(5):1112�1118.
Martin HV, Botella C, Garcıa-Palacios A, Osma J. 2007. Virtual
reality exposure in the treatment of panic disorder with
agoraphobia: A case study. Cogn Behav Pract 14:58�69.
Meehan M, Razzaque S, Insko B, Whitton M, Brooks Jr FP. 2005.
Review of four studies on the use of physiological reaction as a
measure of presence in stressful virtual environments. Appl
Psychophysiol Biofeedback 30(3):239�258.
Moore K, Wiederhold BK, Wielderhold MD, Riva G. 2002. Panic
and agoraphobia in a virtual world. Cyberpsychol Behav
5(3):197�202.
Nesse RM, Curtis GC, Thyer B A, McCann DS, Huber-Smith
MJ, Knopf RF. 1985. Endocrine and cardiovascular responses
during phobic anxiety. Psychosom Med 47(1):320�332.
North MM, North SM, Coble JR. 1997. Virtual reality therapy:
An effective treatment for psychological disorders. Stud Health
Technol Inform 44:59�70.
Othmer S, Kaiser D. 2000. Implementation of virtual reality in
EEG biofeedback. Cyberpsychol Behav 3(3):415�420.
Parsons TD, Rizzo AA. 2008. Affective outcomes of virtual reality
exposure therapy for anxiety and specific phobias: A meta-
analysis. J Behav Ther Exp Psychiatry 39:250�261.
Virtual reality and exposure therapy 229
Wor
ld J
Bio
l Psy
chia
try
Dow
nloa
ded
from
info
rmah
ealth
care
.com
by
Uni
vers
ity o
f V
irgi
nia
on 1
0/30
/13
For
pers
onal
use
onl
y.
Powers MB, Emmelkamp PMG. 2008. Virtual reality exposure
therapy for anxiety disorders: A meta-analysis. J Anxiety Disord
22:561�569.
Price M, Anderson P. 2007. The role of presence in virtual reality
exposure therapy. J Anxiety Disord 21:742�751.
Pull CB. 2005. Current status of virtual reality exposure therapy
in anxiety disorders: editorial review. Curr Opin Psychiatry
18(1):7�14.
Regenbrecht HT, Schubert TW, Friedmann F. 1998. Measuring
the sense of presence and its relations to fear of heights in
virtual environments. Int J Hum Comput Interact 10:233�249.
Riva G. 2005. Virtual reality in psychotherapy: Review. Cyberp-
sychol Behav 8(3):220�230.
Riva G, Wiederhold BK. 2002. Guest Editorial: Introduction to
the Special Issue on Virtual Reality Environments in Behavioral
Sciences. IEEE Trans Inf Technol Biomed 6(3):193�197.
Riva G, Bacchetta M, Baruffi M, Molinari E. 2001. Virtual
reality-based multidimensional therapy for the treatment of
body image disturbances in obesity: a controlled study.
Cyberpsychol Behav 4(4):511�526.
Riva G, Bacchetta M, Baruffi M, Molinari E. 2002a. Virtual
reality-based multidimensional therapy for the treatment of
body image disturbances in binge eating disorders: A pre-
liminary controlled study. IEEE Trans Inf Technol Biomed
6(3):224�234.
Riva G, Molinari E, Vincelli F. 2002b. Interaction and presence in
the clinical relationship: Virtual reality (VR) as communicative
medium between patient and therapist. IEEE Trans Inf
Technol Biomed 6(3):198�205.
Riva G, Bacchetta M, Cesa G, Conti S, Molinari E. 2003. Six-
month follow-up of in-patient experiential cognitive therapy for
binge eating disorders. Cyberpsychol Behav 6(3):251�258.
Robillard G, Bouchard S, Fournier T, Renaud P. 2003. Anxiety
and presence during VR immersion: A comparative study of the
reactions of phobic and non-phobic participants in therapeutic
virtual environments derived from computer games. Cyberp-
sychol Behav 6(5):467�476.
Roth WT, Telch MJ, Taylor CB, Sachitano JA, Gallen CC, Kopell
M.L, et al. 1986. Autonomic characteristics of agoraphobia
with panic attacks. Biol Psychiatry 21:1133�1154.
Rothbaum BO, Hodges LF. 1999. The use of virtual reality
exposure in the treatment of anxiety disorders. Behav Modif
23:507�525.
Rothbaum BO, Hodges L, Alarcon R, Ready D, Shahar F, Graap
K, et al. 1999. Virtual reality exposure therapy for PTSD
Vietnam veterans: A case study. J Trauma Stress 12:263�271.
Rothbaum BO, Hodges L, Smith S, Lee JH, Price L. 2000. A
controlled study of virtual reality exposure therapy for the fear
of flying. J Consult Clin Psychol 68:1020�1026.
Rothbaum BO, Hodges L, Anderson PL, Price L, Smith S. 2002.
Twelve-month follow-up of virtual reality and standard ex-
posure therapies for the fear of flying. J Consult Clin Psychol
70:428�432.
Rothbaum BO, Anderson P, Zimand E, Hodges L, Lang D,
Wilson J. 2006. Virtual reality exposure therapy and standard
(in vivo) exposure therapy in the treatment of fear of flying.
Behav Ther 37(1):80�90.
Sastry L, Boyd DRS. 1998. Virtual environments for engineering
applications. Virtual Reality: Res Dev Appl 3(4):235�244.
Slater M. 2004. Presence and emotions. Cyberpsychol Behav
7(1):121.
Steuer J. 1992. Defining virtual reality: Dimensions determining
telepresence. J Commun 42(4):73�93.
Tichon J, Banks J. 2006. Virtual reality exposure therapy: 150-
degree screen to desktop PC. Cyberpsychol Behav 9(4):480�488.
Vincelli F, Anolli L, Bouchard S, Wiederhold BK, Zurloni V, Riva
G. 2003. Experiential cognitive therapy in the treatment of
panic disorders with agoraphobia: A controlled study. Cyberp-
sychol Behav 6(3):321�328.
Wald J, Taylor S. 2003. Preliminary research on the efficacy of
virtual reality exposure therapy to treat driving phobia.
Cyberpsychol Behav 6(5):459�465.
Wiederhold BK. 2000. Virtual Reality in the 1990s: What did we
learn? Cyberpsychol Behav 3(3):311�314.
Wiederhold BK, Rizzo AS. 2005. Virtual reality and applied
psychophysiology. Appl Psychophysiol Biofeedback 30(3):183�185.
Wiederhold BK, Wiederhold MD. 2000. Lessons learned from
600 virtual reality sessions. Cyberpsychol Behav 3(3):393�400.
Wiederhold BK, Wiederhold MD. 2003. Three-year follow-up for
virtual reality exposure for fear of flying. Cyberpsychol Behav
6(4):441�445.
Wiederhold BK, Jang DP, Gevirtz RG, Kim SI, Kim IY,
Wiederhold MD. 2002a. The treatment of fear of flying: A
controlled study of imaginal and virtual reality graded exposure
therapy. IEEE Trans Inf Technol Biomed 6:218�223.
Wiederhold BK, Jang DP, Kim SI, Wiederhold MD. 2002b.
Physiological monitoring as an objective tool in virtual reality
therapy. Cyberpsychol Behav 5(1):77�82.
Wilhelm FH, Roth WT. 1998. Taking the laboratory to the skies:
Ambulatory assessment of self-report, autonomic, and respira-
tory responses in flying phobia. Psychophysiology 35:596�606.
Wilhelm FH, Pfaltz MC, Gross JJ, Mauss IB, Kim SI, Wiederhold
BK. 2005. Mechanisms of virtual reality exposure therapy: The
role of the behavioral activation and behavioral inhibition
systems. Appl Psychophysiol Biofeedback 30(3):271�284.
Wilson PN, Foreman N, Tlauka M. 1997. Transfer of spatial
information from a virtual to a real environment. Hum Factors
39:526�531.
Witmer BG, Singer MJ. 1998. Measuring presence in virtual
environments: A presence questionnaire. Presence 7(3):225�240.
230 M.R. de Carvalho et al.
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