Using Augmented Reality to Treat Phobias

Published by the IEEE Computer Society 0272-1716/05/$20.00 © 2005 IEEE IEEE Computer Graphics and Applications 31

Moving Mixed Reality into the Real World

Virtual reality (VR) is useful for treatingseveral psychological problems, includ-

ing phobias such as fear of flying, agoraphobia, claus-trophobia, and phobia to insects and small animals.1-5

For example, Carlin et al.,1 Renaud et al.,2 and García-Palacios et al.3 used VR to treat arachnophobia. Botel-la et al.’s telepsychology system used VR to treat phobiato insects and small animals (cockroaches, spiders, andrats).4

We believe that augmented reality (AR) could also beused to treat some psychological disorders. AR and VRshare some advantages over traditional treatments, as

Table 1 (next page) shows. However,AR gives a greater feeling of presence(the sensation of being there) andreality judgment (judging an experi-ence as real) than VR because theenvironment and the elements thepatient uses to interact with theapplication are real. Moreover, in ARusers see their own hands, feet, andso on, whereas VR only simulates thisexperience. With these differences inmind, the question arises as to thekinds of psychological treatments ARand VR are most suited for. AR could

be suitable when the following two premises are met:

■ when patients can use real elements such as theirhands and feet to interact with the application; and

■ when it’s possible to use or reproduce the real envi-ronment (with little cost or time) or to use an alter-native environment.

If both premises aren’t satisfied, VR might be prefer-able. Because neither AR nor VR are a panacea, the pho-bia type will determine the most appropriate technologyto use.

In our system, patients see their own hands, feet, andso on. They can touch the table that animals are cross-ing or seeing their feet while the animals are runningon the floor. They can also hold a marker with a deadspider or cockroach or pick up a flyswatter, a can ofinsecticide, or a dustpan.

System descriptionOur application uses a USB or FireWire camera and

a markera white square with a black border contain-ing symbols or letters. We use a Creative NX-Ultra cam-era in the patient exposure sessions and LogitechQuickCam Pro 4000. We attach the camera to a head-mounted display (HMD) worn by the patient so thecamera focuses where the patient looks, as Figure 1shows. We display the system output on the HMD (weused 5DT’s HMD with 800 × 600 resolution and high[40 degrees] field of view). The therapist watches thetreatment on the monitor, viewing the same scene asthe patient.

We programmed the system in C and used VisualC++ version 6.0 as the development environment. Weused ARToolKit 2.656 with Virtual Reality Modeling Lan-guage (VRML) support to incorporate AR options.(More information about ARToolKit, related publica-tions in PDF, source code for different operating sys-tems, and tutorials are available at http://www.hitl.washington.edu/artoolkit.)

The spiders and cockroaches are the system’s virtualelements. We modeled one cockroach and three types ofspiders (small, medium, and large). We made the ani-mals look as real as possible (see Figure 2) by payingattention to their structure, movements, and texture.We used Autodesk 3ds Max to create the cockroach andspider models and their movement. We then exportedthe models to VRML format and used VrmlPad to editthe objects and modify some characteristics.

We created three models for the spiders and the cock-roach: static, moving, and dead. The moving spidermoves its legs; the moving cockroach moves its feelersand legs. We created textures using Adobe Photoshop7.0 and applied them to the models.

We used the OpenGL Utility Toolkit (GLUT)-baseduser interface library (GLUI) to develop the graphicuser interface. The graphic user interface can show allof the actions the user can select, or it can hide themto show only the image captured by the camera andthe overlapped spiders or cockroaches. If the menu is hidden, the user can control the application usingcomputer keys. We used the OpenAL library forsounds.

Augmented reality systems

give users a feeling of

presence and reality

judgment that can be

exploited to treat some

psychological disorders.

M. Carmen Juan, Mariano Alcañiz, and Carlos MonserratUniversidad Politecnica de Valencia

Cristina BotellaUniversitat Jaume I

Rosa M. Baños and Belen GuerreroUniversidad de Valencia

Using AugmentedReality to TreatPhobias


32 November/December 2005

The system performs the following steps:

1. initializes the video entry, loads the files related tothe markers and the camera, and performs therequired initializations;

2. captures a frame of the video entry;3. searches for possible regions with markers and rec-

ognizes the markers in the captured frame;4. obtains the transformation matrix of the camera

related to the markers that are found;5. draws the virtual objects on the markers;6. repeats steps 2 through 5 for each frame; and7. closes the video entry.

The system executes steps 1 and 7 at the program’sbeginning and end, respectively. Steps 2 through 5 makeup the system loop. While the system executes the loop,it also detects and treats key events and modifies the val-ues of the virtual objects it will draw in step 5. The menuoptions also affect these values. The AR instructionsrelated to all of these steps are ARToolKit instructions.Before drawing the virtual objects in step 5, the systemmust execute required transformations (translation,scale, and rotation).

The system can identify four types of markers in step 3:

■ Animal marker. The system overlays one or more spi-ders or cockroaches in different positions on themarker, depending on how many the user chooses(from 1 to 60).

■ Insecticide killer marker (Figure 3a). The system iden-tifies when this marker is near the animal marker,

Table 1. Advantages of augmented and virtual reality for treating psychological disorders.

Traditional Treatment AR and VR Treatment

Treatment occurs in a real environment, where the Because the elements that the patient fears are elements the patient fears are also real and might virtual, they can’t hurt him or her. not behave as the therapist desires. The therapist might have to take the patient to a In AR or VR scenes, the virtual elements can location the patient fears or re-create it. Access to appear whenever the therapist wants. Access this place could be complicated and the therapy to the scene is as easy as running the program.might require several sessions. The therapist does not control the order in which The therapist controls stimuli generation and stimuli are produced. can repeat the stimuli as many times as

necessary. The therapist also controls the virtual elements’ order of appearance and can start or stop the program at any time.

The therapist cannot ensure that the patient will The virtual elements aren’t real, so there’s no be completely safe during the treatment. real danger to the patient. The real place could be public. The patient The therapist chooses where to run the might suffer a panic attack during the program, so can control all possibilities.treatment, embarrassing both the therapist and the patient.

1 Capture and visualization system (Creative NX-Ultraand 5DT HMD) for an AR system for treating phobias.

2 The threetypes of spidersmodeled: (a) small, (b) medium,and (c) large.

(a) (b) (c)

IEEE Computer Graphics and Applications 33

then it kills one or several spiders or cockroaches. Thesystem plays a squirting sound similar to the soundof a real can of insecticide.

■ Flyswatter marker (Figure 3a). The system identifieswhen this marker is near the animal marker, then itkills one or several spiders or cockroaches. The sys-tem plays a squishing sound similar to what you’dhear if you flattened a real spider or cockroach.

■ Dustpan marker (Figure 3b). The system identifieswhen this marker is near the animal marker. A singledead animal appears on the animal marker, and thedustpan can pick it up. This helps the patient pick upa dead animal and throw it into the trash can.

Users can choose from five menu options or keys tomake one animal appear, three animals appear or dis-appear, or 20 animals appear or disappear.

When the system recognizes the animal marker, itshows the number of selected spiders or cockroaches.If there is only one animal, the image appears in themarker’s center. The system increases or reduces thenumber of animals in increments of three or 20, depend-ing on the selected option. If there are several animals,the system divides them into three groups, dependingon the distance relative to the marker. The first group ison or near the marker, the second group is halfwaybetween the animal marker and the established maxi-mum distance, and the third group is at the farthest dis-tance possible. As animals appear, the first animal goesinto the first group, the second goes into the secondgroup, the third goes into the third group, and then thefourth goes into the first group, and so on until the sys-tem reaches the maximum number of allowed animals(60). This distribution assures that there are always ani-mals near the marker. To provide randomness, each timethe system runs, it assigns a random value to the firstgroup of animals, using this value to rotate the group.These animals therefore have a different orientation ateach run, with the second and third groups always ori-ented toward the marker.

If the user selects one or more animals without move-ment, the static model of the selected animal appears. Ifthe user chooses moving animals, the system displays themoving model. The movement is repetitive. If one spideror cockroach is near the marker and its orientation facesoutward from the image, it starts the movement towardthe outside of the image, moves the established distance,and goes back to its initial position (the distance isn’t thesame for all animals). If the spider or cockroach is as far away as possible, its movement is toward the marker,and the animal returns to its initial position after movingthe specified distance (the final position isn’t the samefor all spiders or cockroaches). If the user stops the move-ment, the system replaces the moving animal with thestatic animal, which remains where it was stopped.When the user selects movement, the animals renewmovement from their current positions.

Users can select two additional actions through asso-ciated keys or menu options:

■ return selected animals to their initial values (that is,their original position and orientation), or

■ increase or reduce the size of the selected animals(that is, modify each animal’s scale factor).

All of the available options let the therapist make thetreatment progressive. The therapist can control howmany spiders or cockroaches appear, their size, whetherthey move, whether to kill a spider or cockroach whenthe patient is prepared, and whether to throw it into atrash can.

Experimental methodWe tested the treatment on nine participants, five

with a phobia of cockroaches and four with a phobia of

3 Elementsused in the ARsystem: (a)insecticide andflyswatter, and(b) dustpan.

(a)

(b)



spiders. All of them sought help at the Jaume I Univer-sity Anxiety Disorders Clinic. They met the Diagnosticand Statistical Manual of Mental Disorders, fourth edi-tion (DSM-IV)7 criteria for specific phobia, situationaltype (specifically, fear of cockroaches and fear of spi-ders). None had previously received treatment for thisproblem.

Participants Participant 1 was a 33-year-old single female who

worked as a hairdresser. Her phobia of spiders beganwhen she was 13 years old. The problem moderatelyinterfered with her life. She had a house in the country,and she avoided going anywhere she believed that spi-ders could appear. She rated her problem’s severity as 7(on a scale from 0 to 10).

Participant 2 was a 21-year-old single female univer-sity student. Her phobia of spiders began when she was5 years old and had become progressively worse. If shesaw a spider, she would cry, shout, and have nightmaresfor several days. She defined it as hysterical reaction,and rated her problem’s severity as 7.

Participant 3 was a 33-year-old married female whoworked in administration at the university. Her phobiaof spiders began when she was a child; her mother toldher that if she didn’t wash her hair, spiders would growin it. She rated her problem’s severity as 8.

Participant 4 was a 19-year-old single male universi-ty student. His phobia of spiders manifested in physicalsensations such as palpitation, sweating, and shivers, aswell as fear of losing control when he saw a spider. Hereported having had a fear of spiders since he was achild. He rated his problem’s severity as 8.

Participant 5 was a 29-year-old single female doctor.She’d had her phobia of cockroaches since she was achild, and this fear had generalized to other insects, suchas butterflies, wasps, and beetles. She rated her prob-lem’s severity as 7.

Participant 6 was a 20-year-old single female univer-sity student. Her phobia of cockroaches began when shewas a child, for no apparent reason. She rated her prob-lem’s severity as 6.

Participant 7 was a 27-year-old single female nursein a residential home for the elderly. Her phobia of cock-roaches began when she was a child and got worse withage. She rated her problem’s severity as 10. There werecockroaches in the home where she worked so she haddecided to leave her workplace.

Participant 8 was a 31-year-old single female whoworked in administration. Her fear of cockroaches beganwhen she was younger and a lot of wasps attacked her.Her fear had expanded to other insects (bees and wasps,for example). She rated her problem’s severity as 8.

Participant 9 was a 35-year-old married female psy-chologist. Her fear of cockroaches began when she was15 years old and there was a plague of cockroaches inthe town where she lived. Her fear was increasing. Sherated her problem’s severity as 6.

MeasuresWe used several common psychiatric testing tools,

which we adapted to our AR system:

■ Diagnostic interview. We adapted the anxiety disor-ders interview schedule, specific phobia section,8 toour system. ADIS-IV is a semistructured interviewdesigned to perform a differential diagnosis of theanxiety disorders included in the DSM-IV.7 It gathersclinical data such as the problem’s history, as well ascognitive and situational factors that could play a rolein the anxiety response’s phenomenology.

■ Fear and avoidance scales. We adapted these scalesfrom Marks’ and Mathews’ work.9 The patient and thetherapist establish the behaviors or situations that thepatient avoids and would like to overcome by the endof the treatment. The patient rates the daily level ofavoidance on a 0 to 10 scale.

■ Measures regarding expectations and satisfaction withthe treatment. We included two questions adaptedfrom Borkovec’s and Nau’s work10 about the patient’swillingness to participate in a treatment program thatincludes in vivo or AR exposure. Patients rated thesequestions on a 1-to-7 scale, where 1 was “I wouldnever do it” and 7 was “I would absolutely do it.” LikeBorkovec and Nau,10 we also included several ques-tions to measure patients’ satisfaction with the ARexposure treatment.

■ Presence and reality judgment. After they interactedwith the AR system, we asked participants to answerthree questions (described later) regarding thedegree of presence they experienced in the AR ses-sion.

■ Subjective units of discomfort scale (SUDS).11 We askedparticipants to rate their maximum level of anxietyon a 0-to-10 scale, where 0 is no anxiety and 10 is highanxiety.

■ Consent form. Participants read and signed a consentform accepting the treatment they were going toreceive and agreeing to let us videotape the sessionsand use their data in our research.

Exposure session We applied the AR system using the “one-session

treatment” guidelines from the treatment developed byÖst, Salkovskis, and Hellstroöm.12

In the AR exposure session, we first put the captureand visualization system on the patient. As the programran, the therapist showed the patient one spider or cock-roach (depending on the patient’s phobia). More of theanimals progressively appeared as the therapist con-sidered it opportune. During the AR session, the patientswere able to view as many as 60 animals at the sametime.

In the second step, the therapist urged the patient tobring his or her hand closer to the therapist’s hand,which spiders or cockroaches were crossing. At first, thetherapist displayed only one animal; later the therapistused two animals, and then progressively more animals.Patients pulled their hands away several times when aspider or cockroach approached and crossed theirhands, as Figure 4a demonstrates.

The therapist introduced a surprise box in the thirdstep to generate uncertainty in the patients. Patientsautomatically associated markers they saw with theappearance of one or more spiders or cockroaches. How-


ever, when patients didn’t know whether there was amarker under a box or inside a cupboard, they didn’tknow if one or more spiders or cockroaches wouldappear. This step simulated searching for a spider orcockroach in your house: You know a spider or cock-roach is there, but you don’t know exactly where it is.The system allows as many surprise boxes as the thera-pist desires; we used four. Under one or two of theseboxes was a marker. When the therapist or the patientpicked up a box, one or more spiders or cockroachesappeared. Again, the therapist picked up boxes with andwithout markers. Later, the patient picked up boxes withor without markers, as Figure 4b shows.

In the fourth step, the therapist started to kill the spi-ders or cockroaches. The therapist first killed one ani-mal, then, after repeating this action several times, thetherapist urged the patient to kill animals and throwthem into a box. Figure 4c shows a participant killing aspider with the flyswatter. Figure 4d shows a participantpicking up the dead cockroach to throw it into a box.

After the AR session, the therapist encouraged thepatients to approach and interact with real spiders orcockroaches. First, the therapist asked the patients toapproach a bowl containing live animals. After thepatients touched the bowl, the therapist took an animalout of the bowl and let it run on the floor. All of the

patients were able to approach the live animal, interactwith it, and kill it by themselves.

ResultsIn all cases, the treatment significantly reduced the

participants’ fear when facing their target animal. Results from the treatment showed an important

change in participants’ avoidance of the animals. Beforethe treatment, none of them could approach real spi-ders or cockroaches. After the treatment, all were ableto kill several live spiders or cockroaches.

Table 2 (next page) shows the results of the participants’self-report measures. During the treatment, the partici-pants’ anxiety scores were high, but they dropped by thetreatment’s end. Analysis of this data indicates that theAR system induces anxiety in people suffering from fear ofspiders or cockroaches. Moreover, the system not onlyinduced anxiety, but it also diminished it through pro-longed exposure to the virtual spiders and cockroaches.Furthermore, the fact that the nine participants could killa live spider or cockroach after the treatment is a mean-ingful measure of improvement. Thus, we could say thatthe AR treatment for fear of spiders and cockroaches suc-cessfully reduced patients’ fear and avoidance.

The time needed to reduce patients’ fear and avoid-ance using our system was also significantly shorter than

4 Exposure session steps. During the session, participants (a) let spiders approach and cross over their hands, (b)picked up a box covering a marker, (c) killed spiders with the flyswatter, and (d) picked up dead cockroaches to putthem into a box.

(a) (b)

(c) (d)



with other VR experiments. Carlin et al.’s first patientneeded 12 one-hour VR therapy sessions to overcomeher fear.1 Participants in García-Palacios et al.’s VR treat-ment group received an average of four one-hour expo-sure therapy sessions to achieve the same objective.3

To measure participants’ sense of presence and real-ity judgment when they were immersed in the system,we asked them three questions:

■ To what degree did you feel present in the situation?■ To what degree did you feel you were in a place in

which animals appeared?■ To what degree did you think the animals were real?

Table 3 shows their answers (labeled Q1, Q2, and Q3in order of list). All of the scores were high, indicatingthat all the participants were able to immerse them-selves in the AR environment and feel as anxious as theywould confronting real spiders or cockroaches.

ConclusionThe positive results of this first prototype suggest AR’s

potential in psychology. The study’s main shortcomingis the small sample size. We need to apply this treatmentto larger samples in a group design that includes a con-trol group. Such a procedure would increase the confi-dence in this new exposure format. We believe that ARapplications can also be useful as a therapeutic tool forseveral other psychological disorders. ■

AcknowledgmentsWe thank César Carrión and Marco Melero for their

assistance in developing this application.

References1. A. Carlin, H. Hoffman, and S. Weghorst, “Virtual Reality

and Tactile Augmentation in the Treatment of Spider Pho-bia: A Case Report,” Behavior Research and Therapy, vol.35, 1997, pp. 153-158.

2. P. Renaud, S. Bouchard, and R. Proulx, “Behavioral Avoid-ance Dynamics in the Presence of a Virtual Spider,” IEEE

Trans. Information Technology in Biomedicine, vol. 6, no. 3,2002, pp. 235-243.

3. A. García-Palacios et al., “Virtual Reality in the Treatmentof Spider Phobia: A Controlled Study Behavior,” Researchand Therapy, vol. 9, 2004, pp. 983-993.

4. C. Botella et al., “Telepsychology and Self-Help: The Treat-ment of Phobias Using the Internet,” Cybertherapy, EEUU,2004, CD-ROM.

5. L. Hodges et al., “Treating Psychological and Physical Dis-orders with VR,” IEEE Computer Graphics and Applications,vol. 21, no. 6, 2001, pp. 25-33.

6. H. Kato and M. Billinghurst, “Marker Tracking and HMDCalibration for a Video-Based Augmented Reality,” Proc.2nd IEEE and ACM Int’l Workshop Augmented Reality(IWAR), IEEE CS Press, 1999, pp. 85-94.

7. Am. Psychiatric Assoc., Diagnostic and Statistical Manualof Mental Disorders, 4th ed., APA, 2000.

8. P.A. Di Nardo, T.A. Brown, and D.H. Barlow, Anxiety Dis-orders Interview Schedule for DSM-IV: Lifetime Version(ADIS-IV), Psychological Corp., 1994.

9. I.M. Marks and A.M. Mathews, “Case Histories and Short-er Communication,” Behavior Research and Therapy, vol.17, 1979, pp. 263-267.

10. T.D. Borkovec and S.D. Nau, “Credibility of Analogue Ther-apy Rationales,” J. Behavior Therapy and Experimental Psy-chiatry, vol. 3, 1972, pp. 257-260.

11. J. Wolpe, The Practice of Behavior Therapy, Pergamon Press,1969.

12. L. Öst, P. Salkovskis, and K. Hellstroöm, “One-Session Ther-apist-Directed Exposure vs. Self-Exposure in the Treatmentof Spider Phobia,” Behavior Therapy, vol. 22, 1991, pp. 407-422.

M. Carmen Juan is a senior lecturer in computer science at the Universidad Politecnica de Valencia,Spain. Her research interests includeAR applied to psychological treat-ments. Juan has a PhD in computerscience from the Technical University

of Valencia. Contact her at [email protected].

Table 2. Participants’ degree of anxiety whenconfronting target animals (on a scale of 1 to10).

During AfterParticipant Exposure Treatment

1 9 0 2 9 5 3 10 3 4 7 0 5 9 0 6 10 5 7 10 2 8 8 0 9 8 0

Table 3. Participants’ sense of presence andreality judgment (on a scale of 1 to 10).

Participant Q1 Q2 Q3

1 10 8 9 2 7 5 6 3 8 8 8 4 10 10 9 5 7 7 7 6 10 10 10 7 10 10 10 8 8 8 8 9 10 10 8


Mariano Alcañiz is a professor ofcomputer graphics and director of theMedical Image Computing Laborato-ry. His research interests involve com-puter methods and algorithms formedical image processing, 3D medicalimaging, computer-integrated surgery,

and VR technology applied to medicine. Alcañiz has a PhDin industrial engineering at the Technical University ofValencia. Contact him at [email protected].

Carlos Monserrat is a computerengineer in the MedICLab researchgroup at the Universidad Politecnicade Valencia. His research interestsinclude deformable models. Monser-rat has a PhD in computer sciencefrom the Technical University of Valen-

cia. Contact him at [email protected].

Cristina Botella is a professor ofclinical psychology and the director ofthe Emotional Disorders Clinic at Uni-versitat Jaume I. Her main researchinterest is the application of new tech-nologies to the field of clinical psy-chology. Botella has a PhD in clinical

psychology from the University of Valencia. Contact her [email protected].

Rosa M. Baños is a senior lecturerin psychopathology at the Universidadde Valencia, Spain. Her research inter-ests include psychopathology, thetreatment of psychological disorders,and the application of VR to psychol-ogy. She has a PhD in psychology from

the University of Valencia. Contact her at [email protected].

Belen Guerrero is a clinical psy-chologist at Previ SL. Her researchinterests focus on the application of VRin clinical psychology. Guerrero has aPhD in psychology from the Universi-ty of Malaga, Spain. Contact her [email protected].

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Using Augmented Reality to Treat Phobias