Behaviour Research and Therapy 40 (2002) 983–993 www.elsevier.com/locate/brat
Virtual reality in the treatment of spider phobia: a controlled
, H. Hoffman
, A. Carlin
, T.A. Furness III
Departamento Psicologia Basica Clinica y Psicobiologia, Universidad Jaume I, Campus Borriol, Ctra Borriol s/n,
12080 Castellon, Spain
Human Interface Technology Laboratory, Box 352142, 215 Fluke Hall, University of Washington, Seattle, WA
Department of Psychology, University of Washington, Seattle, WA 98195-2142, USA
Accepted 1 July 2001
This study explored whether virtual reality (VR) exposure therapy was effective in the treatment of
spider phobia. We compared a treatment condition vs. a waiting list condition in a between group design
with 23 participants. Participants in the VR treatment group received an average of four one-hour exposure
therapy sessions. VR exposure was effective in treating spider phobia compared to a control condition as
measured with a Fear of Spiders questionnaire, a Behavioural Avoidance Test (BAT), and severity ratings
made by the clinician and an independent assessor. Eighty-three percent of patients in the VR treatment
group showed clinically signiﬁcant improvement compared with 0% in the waiting list group, and no
patients dropped out. This study shows that VR exposure can be effective in the treatment of phobias.
2002 Elsevier Science Ltd. All rights reserved.
Keywords: Virtual reality; Exposure therapy; Spider phobia
An estimated 10–11% of the US population experiences a speciﬁc phobia at some point in
their lives, (American Psychiatric Association, 1994; Magee, Eaton, Wittchen, McGonagle &
Kessler, 1996). Approximately 40% of speciﬁc phobias belong to the category of “bugs (including
* Corresponding author. Tel.: +34-964-729353; fax: +34-964-729350.
E-mail address: email@example.com (A. Garcia-Palacios).
0005-7967/02/$ - see front matter 2002 Elsevier Science Ltd. All rights reserved.
984 A. Garcia-Palacios et al. / Behaviour Research and Therapy 40 (2002) 983–993
spiders), mice, snakes or bats”(Chapman, 1997). Spider phobics characteristically display a per-
sistent fear of spiders, an immediate anxiety response upon exposure to a spider, and avoidance of
spiders. Phobics often recognize that their fear is excessive or unreasonable (American Psychiatric
Association, 1994). In fact, for some, fear of the irrational reaction they will have when encoun-
tering a spider (losing control, panic attack) is a major source of their anxiety. Consistent with
Rachman’s theory (1976, 1977) about the acquisition of phobias, Ost and Hugdahl (1981) found
that the majority of phobics reported acquiring their fear via conditioning (58%). Others reported
instruction (e.g. by their parents) as the source of their phobia (10%), acquired their fear vicari-
ously (15%), or couldn’t remember (10%).
‘In vivo’exposure therapy has been used successfully with a wide range of phobias including
fear of spiders (Craske & Rowe, 1997; Marks, 1987; Ost, 1997) and is considered to be the
treatment of choice for speciﬁc phobias (Antony & Swinson, 2000; Marks, 1987; Mathews, 1978).
With in vivo therapy for spider phobia, patients gradually and systematically approach closer to
a live spider over a period of several one-hour sessions. Some researchers have had great success
treating spider phobics in an accelerated single massed three-hour in vivo exposure session, both
with individuals and group sessions (see Ost, 1997 for a review). However, the experience is
likely more distressing for the patients than multiple sessions distributed over a period of days,
weeks or months. In general, for patients motivated enough to seek therapy for their phobia,
single session in vivo exposure therapy has a high success rate (Ost, 1996), and fear reduction
tends to be long term, with low relapse rates. Imagery exposure therapy, having the patient
imagine situations involving spiders, can also be effective (Hecker, 1990), but is limited by the
fact that some patients have trouble imagining spiders, and/or the imagined spiders do not elicit
sufﬁcient anxiety to be valuable.
Unfortunately, around 60–85% of those afﬂicted with speciﬁc phobias never seek treatment for
their problem (Agras, Sylvester, & Oliveau, 1969; Boyd et al., 1990; Magee et al., 1996). Many
phobics are probably too afraid of confronting the feared object or situation to seek therapy
(Marks, 1992). Now that researchers and therapists have succeeded in developing and testing
effective ways of treating phobias, new efforts are needed to increase the number of phobia
sufferers who seek treatment.
In a recent study, Garcia-Palacios, Hoffman, Kwong See, Tsai, & Botella (2001) surveyed a
total of 777 undergraduate students. Participants read a brief general description of how exposure
therapy works, and were asked about their willingness to get involved in two different ways of
applying the therapy to spider phobia, in vivo exposure or virtual reality (VR) exposure. Garcia
et al. found that people high in fear of spiders (over one SD above the sample mean on a fear
of spiders questionnaire) strongly preferred VR exposure treatment (81% in study 1 and 89% in
study 2) compared to in vivo exposure therapy. Furthermore, in study 2, only 8% of fearful
students said they would ‘absolutely not’be willing to come in for three, one-hour VR exposure
therapy sessions, whereas 34% of fearful students said ‘absolutely not’to one massed three-hour
in vivo therapy session.
Immersive VR works as follows. The subject dons a ‘VR Helmet’that positions two goggle
sized TV screens close to the user’s eyes. Each eye gets a slightly different image of the virtual
world. The image shown to the left eye is offset slightly from that seen by the right eye. The
brain fuses these two images into a single 3-D image, helping to give users the illusion that the
virtual environment has depth. Position tracking devices keep the computer informed of changes
985A. Garcia-Palacios et al. / Behaviour Research and Therapy 40 (2002) 983–993
in the user’s head and hand locations. The scenery in VR changes as the user moves his/her head
orientation (e.g. virtual objects in front of the user in VR get closer as the user, wearing his/her
VR helmet, leans forward in the real world). Any one of these techniques alone might be uncon-
vincing, but combined, they give users a uniquely compelling experience of ‘being there’in the
virtual world. The essence of immersive VR is the illusion it gives users that they are inside the
computer-generated environment, as if they are ‘there’in the virtual world. In the present study,
the place our patients visited was a virtual kitchen, and the virtual object they picked up was the
plump furry body of a virtual Guyana bird-eating tarantula.
To make VR more convincing, tactile augmentation can enhance the quality of the virtual
world. With this technique, real objects are used as props in the interaction with 3-D VR graphics
(Hoffman, 1998; Hoffman et al., 1996; Hoffman, Holander, Schroder, Rousseau, & Furness,
1998). Pilot studies and case reports suggest that VR exposure therapy can be an effective medium
for the reduction of speciﬁc phobias such as fear of heights (Rothbaum et al., 1995), fear of ﬂying
(Hodges, Rothbaum, Watson, Kessler, & Opdyke, 1996), claustrophobia (Botella et al., 1998;
˜os, Villa, Perpin
`, & Garcia-Palacios, 2000) and spider phobia (Carlin, Hoffman, &
Weghorst, 1997). Recent controlled studies have shown that VR exposure therapy was as effective
as in vivo exposure to treat ﬂying phobia (Rothbaum, Hodges, Smith, Lee, & Price, 2000) and
fear of heights (Emmelkamp et al., in press).
The present study is the ﬁrst controlled study to test whether immersive VR exposure therapy
is effective for treating spider phobia. We compared the effectiveness of VR exposure vs. a
waiting list condition. Practical implications of our ﬁndings are discussed.
Participants were recruited from different sources: (a) mass testing in an introductory Psy-
chology class; (b) through advertisements in the University newspaper and (c) from people who
contacted us requesting treatment for their fear of spiders. Participants from mass testing com-
pleted a fear of spiders questionnaire (Szymanski & O’Donohue, 1995). Students scoring over
two standard deviation above the class mean in fear of spiders (i.e. a score greater than 97) were
invited to undergo exposure therapy for fear of spiders. These students received extra credit in
their class for participating. Thirty participants were invited. To participate in the study, subjects
had to meet the following criteria: (1) meet DSM-IV (American Psychiatric Association, 1994)
criteria of Speciﬁc Phobia, Animal Type (spiders) according to the judgement of two clinical
Psychologists, one of them, blind to the conditions of the study; (2) a minimum of one-year
duration of the phobia; (3) patient must not be able to remove the lid of a cage with a tarantula
prior to treatment, during the Behavioural Avoidance Test (BAT); (4) have no other psychiatric
problem in immediate need of treatment; (5) no current alcohol or drug dependence; (6) no severe
Twenty-three participants met the inclusion criteria and took part in the study. Of the thirty
persons invited to participate, four were excluded from the experiment because they did not meet
the DSM-IV criteria for Speciﬁc Phobia according to the judgement of the interviewer or of a
986 A. Garcia-Palacios et al. / Behaviour Research and Therapy 40 (2002) 983–993
blind clinician who made a diagnostic judgement after listening to the interviews. Three more
participants were excluded because they were able to remove the lid during the BAT.
The average age was 29.25 years (SD=10.79; range 18–58). Most participants were female
(90.9%) and only 9.1% were male. The mean reported duration of their fear was 21 years
(SD=11.76; range 6–50 years). One participant had received previous psychological treatment for
fear of spiders without success.
A Silicon Graphics
Octane MXE with Octane Channel Option (allowing stereo vision) coupled
with a relatively wide ﬁeld-of-view (60°diagonal) head mounted visual display
(www.VirtualResearch.com) V8 helmet was used to create an immersive, 3-D, interactive, com-
puter-simulated environment. A PolhemusFastrak position tracking system was used to measure
the position of the user’s head and hand position, and the location of the virtual spider. The
patients experienced SpiderWorld, a modiﬁed version of KitchenWorld
2.3.1. Anxiety Diagnostic Interview Schedule IV (ADIS-IV)
During this ADIS-IV (Di Nardo, Brown, & Barlow, 1994), the patient was asked about each
criteria of DSM-IV speciﬁc phobia, animal type (American Psychiatric Association, 1994). We
also obtained information on demographic and clinical variables: the duration of the problem,
severity of the phobia as perceived by the patient, former treatments, and presence of other
psychological or physical problems.
2.3.2. Fear of spiders questionnaire
This questionnaire (Szymanski & O’Donohue, 1995) was chosen as a subjective measure of
the efﬁcacy of VR treatment. Previous researchers have found this questionnaire to have excellent
split half reliability and internal consistency, good test–retest consistency, convergent validity due
to its highly signiﬁcant correlations with a BAT (r=0.65, p⬍0.001), and construct validity in its
ability to discriminate phobics from non-phobics as measured by a BAT (O’Donohue & Szyman-
ski, 1993; Szymanski & O’Donohue, 1995; see also Muris & Merckelbach, 1996). The question-
naire has 18 items rated on a 1–7 scale (1=does not apply to me, 7=very much applies to me)
about fear and avoidance regarding spiders.
2.3.3. Behavioural Avoidance Test (BAT)
The BAT is a popular objective measure of clinical progress in overcoming phobias. A large
spider (tarantula) was placed in a glass cage with a lid. The cage was placed on a table at the
far end of a room 5 m from the entrance. The patient was instructed to enter the room, walk up
to the cage and remove the lid. Participants were informed that the BAT was an objective measure
Silicon Graphics, Inc. 2011 N. Shoreline Blvd. Mountain View, CA 94043, USA, http://www.sgi.com
Division Incorporated, 1400 Fashion Island Blvd, Suite 510, San Mateo, CA 94404, http://www.division.com/
987A. Garcia-Palacios et al. / Behaviour Research and Therapy 40 (2002) 983–993
of how afraid they were of spiders and not part of the therapy. During the test, the experimenter
remained just outside the door of the room to minimize the possible impact of his presence. When
the participants approached as close to the spider as they could, the distance in meters from the
participant to the spider was measured, and participants rated their anxiety using the subjective
units of discomfort scales (Wolpe, 1969). The distance measure was converted to a behavioural
score that ranged from 0 to 8; where 0=refuses to enter the room, 1=stops 5 m from the container,
2=stops 4 m from the container, 3=stops 3 m from the container, 4=stops 2 m from the container,
5=stops 1 m from the container, 6=stops close to the container, 7=touches the container,
8=removes the lid. After the BAT, the experimenter, who was blind to the experimental condition
to which the patient belonged, rated the severity of the patient’s phobia on a scale from 0 to 8;
where 0=free of symptoms and 8=extremely disabling.
2.3.4. Clinician rating
This scale was the same as that used by Ost, Stridh and Wolf (1998). The clinician rated the
severity of the patient’s phobia on a scale from 0 to 8 where 0=symptom free and 8=extremely
severe and disabling, all aspects of life affected.
2.3.5. Clinically signiﬁcant improvement
We choose our criteria to decide when a patient had achieved a clinically signiﬁcant improve-
ment following Ost et al. (1998) criteria, based on the Jacobson, Follette, & Revenstorf (1984)
guidelines. To meet the criterion for a clinically signiﬁcant improvement in spider phobia, the
change from pre- to post-treatment must be statistically signiﬁcant and the post-test score must
be within the range of a normal sample or outside the range of the patient group, that is, M±2SD
in the direction of functionality.
BAT score (0–8): The change must be 2 points and the cut-off score 7 (touching the container).
BAT assessor rating of phobic severity (0–8): The change must be 2 points and the cut-off
Clinician rating of phobic severity (0–8): The change must be 2 points and the cut-off score 4
Fear of spiders questionnaire: The score must be outside the range of the patient group, that
is, M±2SD in the direction of functionality. The mean was 98.65 and the standard deviation
was 15.73. The cut-off score was 67.
During the pre-treatment assessment, participants were interviewed to determine if they met
criteria for speciﬁc phobia, animal type, spiders (DSM-IV, American Psychiatric Association,
1994) using the structured interview ADIS-IV (Di Nardo et al., 1994). These interviews were
We used two measures of severity, the assessor rating during the BAT and the clinician rating. It could be argued that those
measures are too similar. The reason for doing so was to control assessor’s bias. The measure during BAT was done by an independent
assessor, blind to the experimental conditions and the clinician rating was done by the clinicians who carried out the diagnostic
interviews and the treatments and who were aware of the experimental condition the participants belonged to.
988 A. Garcia-Palacios et al. / Behaviour Research and Therapy 40 (2002) 983–993
audiotaped and another clinician, blind to the study, made a diagnosis. Then patients completed
a questionnaire assessing their fear of spiders, and were given the BAT. The participants who
satisﬁed the entry criteria were randomly assigned to one of the two conditions: VR exposure
group or waiting list control group.
During the post-treatment assessment, participants were given the same measures as pre-treat-
ment except the diagnostic interview. Participants in the waiting list group went through the two
assessment sessions within one or two weeks with no treatments between assessments. Afterwards
they were offered treatment. The participants in the treatment group received several one-on-
one clinical VR exposure therapy sessions for treatment of spider phobia. Each session lasted
approximately one hour and participants completed all sessions and the post-treatment assessment
within two or three weeks of beginning treatment.
Treatment consisted of a standardized exposure protocol delivered by two experienced clinical
psychologists trained in Experimental Psychology (authors A.G. and A.C.). The treatment was
composed of gradual exposure tasks. There was no ﬁxed number of sessions. We established a
criterion to deﬁne the completion of treatment. To have completed treatment the patient must be
able to achieve a ﬁnal exposure goal, holding a big virtual spider with tactile feedback while
reporting low levels of anxiety. The average number of sessions to achieve this goal was four
and it ranged from 3 to 10. On the ﬁrst sessions, participants saw a virtual spider in a virtual
kitchen and approached as closely as they could using their 3-D wand to navigate through the
virtual world. The goal was to come within arms reach of the virtual spider. During the following
session/s, participants touched the virtual spider with their cyber hand (with no tactile feedback).
The virtual spider responded to being touched by ﬂeeing. Patients then picked up a virtual ‘spider
vase’with their cyberhand. When they let go of the virtual vase, an animated spider with wiggly
legs drifted to the ﬂoor of the virtual kitchen accompanied by a brief sound effect from the movie
Psycho. Participants repeated this task until they reported little anxiety. During the last therapy
sessions, the participants were encouraged to touch the virtual spider image with their cyberhand.
Participants reached out their cyberhand and physically touched the visual image of the wiggly
legged virtual Guyana bird-eating tarantula. As the patients reached out with their cyberhand to
explore the virtual spider, their real hand explored the toy spider attached to a stationary Polhemus
position sensor. The virtual spider now felt furry and solid (Hoffman, 1998).
2.5.1. Pre-treatment tests
No differences were found between the waiting list condition and the treatment condition at
pretreatment in demographic and clinical variables: age, t(19) =0.67, p⬎0.05, NS, duration of
the fear, t(18) =0.89, p⬎0.05, NS, and level of perceived impairment, t(21) =1.31, p⬎0.05, NS.
The t-tests showed no signiﬁcant differences between the two groups with respect to the measures
of the behavioural avoidance test at pretreatment: avoidance, t(21) =1.71, p⬎0.05, NS, level of
anxiety reported during the bat, t(21) =0.78, p⬎0.05, NS, and independent assessor rating of
phobic severity on the bat, t(21) =0.78, p⬎0.05, NS. With regard to other measures, no differences
between the two groups were found in the subjective measure of fear of spiders (FSQ) at pretreat-
989A. Garcia-Palacios et al. / Behaviour Research and Therapy 40 (2002) 983–993
ment, t(21) =0.39, p⬎0.05, NS, nor in the clinician rating of phobic severity, t(21) =0.21,
2.5.2. Pre-Post tests
We conducted a 2 (group) by 2 (time=pre- vs. post-treatment) repeated measures ANOVA for
each outcome measure to test the effectiveness of VR exposure. Means and standard deviations
at the pre- and post-test assessments are shown in Table 1.
188.8.131.52. Score on the BAT For the BAT, the ANOVA regarding avoidance showed a signiﬁcant
Group effect, F(1,21)=17.10, p⬍0.001, MSe=7.37, with an effect size of 0.45, a signiﬁcant Time
effect F(1,21)=25.25, p⬍0.001, MSe=2.08, with an effect size of 0.55, and a signiﬁcant Group
by Time interaction F(1,21)=17.40, p⬍0.001, MSe=2.08, with an effect size of 0.45. The interac-
tion indicates that the groups differed in amount of improvement. As shown in Table 1, the VR
exposure group showed greater improvement than the waiting list group.
184.108.40.206. Anxiety during the BAT The mixed-model ANOVA showed no signiﬁcant Group effect,
F(1,21)=1.29, NS, with an effect size of 0.06, a signiﬁcant Time effect F(1,21)=18.23, p⬍0.001,
MSe=284.79, with an effect size of 0.48, and a signiﬁcant Group by Time interaction
F(1,21)=5.99, p⬍0.05, MSe=284.79, with an effect size of 0.23. The interaction indicates that
the VR treatment group showed signiﬁcantly greater reduction in anxiety than the control group.
Mean and standard deviations for the outcome measures at pre- and post-treatment (note: VRE=Virtual Reality
Exposure; WL=Waiting List; BAT=Behavioural Avoidance Test)
VRE (N=12) WL (N=11)
Variable MSD MSD
Pretreatment 3.08 2.19 1.54 2.12
Postreatment 7.00 2.29 1.90 2.07
Pretreatment 82.36 14.44 76.73 14.03
Postreatment 48.18 27.59 67.45 14.01
BAT assessor rating
Pretreatment 6.79 0.89 6.50 0.89
Postreatment 1.74 2.11 6.27 0.65
Fear of spider questionnaire
Pretreatment 97.42 17.51 100.00 14.25
Postreatment 57.42 19.07 97.09 13.44
Pretreatment 6.08 1.24 6.18 0.98
Postreatment 2.42 1.68 5.91 0.94
990 A. Garcia-Palacios et al. / Behaviour Research and Therapy 40 (2002) 983–993
220.127.116.11. Independent assessor rating of phobic severity on the BAT The ANOVA showed a
signiﬁcant Group effect, F(1,21)=22.23, p⬍0.001, MSe=2.32, with an effect size of 0.51, a sig-
niﬁcant Time effect F(1,21)=79.89, p⬍0.001, MSe=1.00, with an effect size of 0.79, and a sig-
niﬁcant Group by Time interaction F(1,21)=66.72, p⬍0.001, MSe=1.00, with an effect size of
0.76. Again, these results revealed that the VR treatment group showed signiﬁcantly greater
reduction than the waiting list group in the severity perceived by an independent assessor on
18.104.22.168. Fear of spiders questionnaire A mixed-model ANOVA regarding this measure showed
a signiﬁcant Group effect, F(1,21)=14.09, p⬍0.001, MSe=363.68, with an effect size of 0.40, a
signiﬁcant Time effect (pre-treatment vs. post-treatment), F(1,21)=31.07, p⬍0.001, MSe=170.07,
with an effect size of 0.60, and a signiﬁcant Group by Time interaction F(1,21)=23.21, p⬍0.001,
MSe=170.07, with an effect size of 0.53. The interaction reveals that the amount of fear of spiders
reduction was not the same for each group. The treatment group achieved greater improvement
than the waiting list control group.
22.214.171.124. Clinician rating of phobic severity The analysis showed a signiﬁcant Group effect,
F(1,21)=14.67, p⬍0.001, MSe=2.52, with an effect size of 0.41, a signiﬁcant Time effect,
F(1,21)=69.67, p⬍0.001, MSe=0.64, with an effect size of 0.77, and a signiﬁcant Group by Time
interaction F(1,21)=51.71, p⬍0.001, MSe=0.64, with an effect size of 0.71. The interaction reveals
that the reduction in severity rated by the therapist was not the same for each group. The treatment
group achieved greater improvement than the waiting list control group.
126.96.36.199. Clinically signiﬁcant improvement Eighty-three percent of the participants in the VR
exposure group achieved a clinically signiﬁcant improvement using strict criteria. None of the
participants in the waiting list group showed clinically signiﬁcant improvement on the post-test.
188.8.131.52. Drop-out None of the participants refused treatment, and none of them dropped out
of the study.
Using both objective and subjective measures of fear, VR exposure with tactile augmentation
signiﬁcantly reduced fear and avoidance of spiders after an average of four, one-hour VR therapy
sessions. This is the ﬁrst controlled study to demonstrate the effectiveness of VR exposure therapy
for treatment of fear of spiders.
VR exposure was more effective than a waiting list control condition in reducing the main
features of a speciﬁc phobia. Fear and avoidance were measured with a fear of spiders question-
naire, a BAT, and severity ratings made by the clinicians and an independent assessor. The VR
treatment group showed improvement on all measures, whereas the control group showed no
The change was not only statistically signiﬁcant, but also clinically signiﬁcant. Eighty-three
percent of the participants in the treatment condition met strict criteria of clinically improved and
991A. Garcia-Palacios et al. / Behaviour Research and Therapy 40 (2002) 983–993
none of the patients in the waiting list condition did so. Most of the patients in the VR group
achieved a signiﬁcant change (M±2SD in the direction of functionality) in important outcome
variables such as avoidance measured in the BAT, the fear of spiders questionnaire, and severity
ratings by an independent assessor and the therapist.
None of the participants who started the VR treatment dropped out. This result supports the
idea that VR exposure is an attractive technique for phobic sufferers that may help to increase
the number of phobics who complete treatment.
In the present study, desensitization to the virtual spider generalized to real spiders. After
treatment, participants were able to approach a large live tarantula on the BAT with low to moder-
ate levels of anxiety.
Despite these ﬁndings we would like to address some of the limitations of our study. The
sample was carefully selected, but relatively small. Studies with larger samples are needed.
Another limitation is that we did not include a follow-up assessment (e.g. 6 months later).
Our results support our prediction that VR can be used to effectively treat a speciﬁc phobia.
However, why use VR when in vivo exposure therapy is so effective? VR gives the patient and
therapist the ability to control the feared object. For example, unlike a real spider, virtual spiders
obey commands, can be placed in various positions and orientations, and can be touched without
danger. VR allows the therapist to control how frightening the spider appears and allows patients
to confront fears that are not easily accessible. For example, in vivo exposure of fear of ﬂying
can be an expensive project. Therapists report difﬁculty with numerous logistic problems and
expenses, such as getting to the airport and renting a commercial jet for the purpose of treating
patients and having to buy airline tickets (Hodges et al., 1996). Conﬁdentiality is another problem-
atic issue for in vivo exposure sessions such as treating fear of heights in a hotel elevator, where
the public can see the patient getting treated. Another advantage of VR is the possibility of treating
‘residual fears’, given the fact that VR can go beyond what a real situation would allow, making
overlearning easier to perform (Botella et al., 1998). VR provides a controlled and protected
environment that allows patients who were reluctant to start an exposure program more willing
to get involved in treatment (Garcia-Palacios et al., 2001). VR treatment is presently a relatively
expensive treatment, due to the additional equipment and software required. However, the price
of VR systems is dropping quickly and dramatically, largely because conventional desktop PC
systems are becoming powerful enough to handle the computational demands of real time VR
(Botella et al., 1999). Emmelkamp has reported results of a VR exposure treatment as effective
as an in vivo treatment for acrophobia using a conventional PC (Emmelkamp et al., in press).
Results of the present study indicate that VR exposure could offer an attractive alternative for
patients unwilling or unable to complete in vivo exposure therapy. VR exposure has potential as
a new medium for an old, well-established technique (graded exposure therapy). A medium that
makes exposure less aversive and more attractive to patients is likely to increase the proportion
of phobia sufferers who seek treatment. The high success rate of VR therapy found in the present
study, and its appeal to people with fear of spiders suggest that VR is a medium worthy of further
exploration for clinical applications.
992 A. Garcia-Palacios et al. / Behaviour Research and Therapy 40 (2002) 983–993
Thanks to Ian Dillon and Silicon Graphics, Inc. for their invaluable equipment support, Division
Ltd for VR software, Ari Hollander (www.imprintit.com) and Duff Hendrickson
(http://www.hitl.washington.edu/people/duff/) for virtual spider programming and modelling, and
Ross Chambers for fundraising. The research presented in this paper was funded by Pla de Promo-
cio de la Investigacio, Fundacio Caixa Castello-Bancaixa 1999, 2000, the University of Wash-
ington Royalties Research Fund, the E.K. and Lillian F. Bishop Foundation, the Paul Allen Foun-
dation for Medical Research.
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