Virtual reality as a mechanism for exposure therapy

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

222 M.R. de Carvalho et al.

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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


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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


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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


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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.


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