albert skip rizzo a swot analysis of the field of ... · the use of virtual-reality technology in...

Albert ldquoSkiprdquo RizzoIntegrated Media Systems CenterUniversity of Southern CaliforniaLos Angeles Californiaarizzouscedu

Gerard Jounghyun KimVirtual Reality LaboratoryDepartment of Computer Scienceand EngineeringPohang University of Science andTechnology (POSTECH)Pohang South Korea

Presence Vol 14 No 2 April 2005 119ndash146

copy 2005 by the Massachusetts Institute of Technology

A SWOT Analysis of the Field ofVirtual Reality Rehabilitationand Therapy

Abstract

The use of virtual-reality technology in the areas of rehabilitation and therapy continuesto grow with encouraging results being reported for applications that address humanphysical cognitive and psychological functioning This article presents a SWOT(Strengths Weaknesses Opportunities and Threats) analysis for the field of VR rehabili-tation and therapy The SWOT analysis is a commonly employed framework in thebusiness world for analyzing the factors that influence a companyrsquos competitive positionin the marketplace with an eye to the future However the SWOT framework can alsobe usefully applied outside of the pure business domain A quick check on the Internetwill turn up SWOT analyses for urban-renewal projects career planning website designyouth sports programs and evaluation of academic research centers and it becomesobvious that it can be usefully applied to assess and guide any organized human en-deavor designed to accomplish a mission It is hoped that this structured examination ofthe factors relevant to the current and future status of VR rehabilitation will provide agood overview of the key issues and concerns that are relevant for understanding andadvancing this vital application area

1 Introduction

Virtual reality (VR) has now emerged as a promising tool in many do-mains of therapy and rehabilitation (Weiss amp Jessel 1998 Glantz Rizzo ampGraap 2003 Zimand et al 2003 Rizzo Schultheis Kerns amp Mateer 2004)Continuing advances in VR technology along with concomitant system-costreductions have supported the development of more usable useful and acces-sible VR systems that can uniquely target a wide range of physical psychologi-cal and cognitive rehabilitation concerns and research questions What makesVR application development in the therapy and rehabilitation sciences so dis-tinctively important is that it represents more than a simple linear extension ofexisting computer technology for human use VR offers the potential to createsystematic human testing training and treatment environments that allow forthe precise control of complex immersive dynamic 3D stimulus presentationswithin which sophisticated interaction behavioral tracking and performancerecording is possible Much like an aircraft simulator serves to test and trainpiloting ability virtual environments (VEs) can be developed to present simu-lations that assess and rehabilitate human functional performance under arange of stimulus conditions that are not easily deliverable and controllable inthe real world When combining these assets within the context of functionally

Rizzo and Kim 119

relevant ecologically enhanced VEs a fundamental ad-vancement could emerge in how human functioningcan be addressed in many rehabilitation disciplines

But we know that already What we donrsquot know isWhat place will VR occupy in the future of rehabilitation

Depending on who you ask yoursquore likely to hear avariety of responses to that question that might includesuch words as ldquoVisionaryrdquo ldquotoo expensiverdquo ldquojust whatthe field needsrdquo ldquobut how will that impact the thera-pistrsquos rolerdquo ldquosounds like the Holodeckrdquo ldquoneed betterinterfacesrdquo ldquohmm interesting possibilitiesrdquo ldquocanthey really do thatrdquo and so forth In essence the viewthat one takes of VR and its potential to add valueover existing rehabilitation tools and methods is ofteninfluenced by such factors as onersquos faith in technol-ogy economic concerns frustration with the existinglimitations of traditional tools fear of technologypopular-media influences pragmatic awareness ofcurrent hardware limitations curiosity and healthyskepticism

For those working in the ldquotrenchesrdquo trying to employVR in a meaningful way for rehabilitation purposes (or forthose just getting their feet wet) a more systematic strat-egy for evaluating the state of the field could be of valuefor informing onersquos judgment decision making andguesses as to whatrsquos possible now and what lies ahead inthe future Without applying a structured framework to aidonersquos thinking about the current status and future of VRand rehabilitation it is quite easy to regularly oscillate be-tween flights of wishful thinking and bouts of abject dis-couragement depending on the daily ebb and flow of pro-vocative data and system crashes Perhaps our susceptibilityto this sort of bipolar ldquosecond-guessingrdquo of VR could bereduced if one is armed with a comprehensive yet intuitivemethod for organizing the myriad factors that will serveboth to enable and to limit how well we can successfullytranslate our virtual-reality rehabilitation vision into actualreality Such a strategy may also help us to identify realisticgoals and establish priorities regarding which clients arethe most appropriate candidates for VR and which tech-nologies are best suited to creating applications to meettheir needs Although a high capacity to live with ambigu-ity is a requirement for those who explore novel emergingapproaches in any discipline a focused approach for guid-

ing our expectations could make that process more man-ageable and productive in the long run

In view of these issues this paper will present aSWOT analysis for the field of VR and the rehabilitationsciences (see Figure 1) SWOT is actually an acronymthat stands for strengths weaknesses opportunities andthreats and is a commonly employed framework in thebusiness world for analyzing the factors that influence acompanyrsquos competitive position in the marketplace withan eye to the future A classic success story for the valueof a SWOT analysis is Dell Computer Corporationrsquos useof the framework to make the strategic decision to im-plement mass customization just-in-time manufactur-ing and direct Internet sales (Collett 1999) Howeverthe SWOT framework can also be usefully applied out-side of the pure business domain A quick check on theInternet will turn up SWOT analyses for urban-renewalprojects career planning website design youth sportsprograms evaluation of academic research centers andit becomes obvious that it can be usefully applied toguide any organized human endeavor designed to ac-complish a mission

Generally a SWOT analysis serves to uncover the op-timal match between the internal strengths and weak-nesses of a given entity and the environmental trends(opportunities and threats) that the entity must face inthe marketplace

A strength can be viewed as a resource a uniqueapproach or capacity that allows an entity toachieve its defined goals (eg VR can allow for pre-cise control of stimulus delivery within a realistictraining or rehabilitation simulation)

A weakness is a limitation fault or defect in theentity that impedes progress toward defined goals(eg the limited field of view and resolution in ahead-mounted display can limit usability and per-ceptual realism)

An opportunity pertains to internal or externalforces in the entityrsquos operating environment suchas a trend that increases demand for what the entitycan provide or allows the entity to provide it moreeffectively (eg tremendous growth in the interac-tive digital gaming area has driven development of

120 PRESENCE VOLUME 14 NUMBER 2

the high-quality yet low-cost graphics cards neededto make VR deliverable on a basic PC)

A threat can be any unfavorable situation in the enti-tyrsquos environment that impedes its strategy by present-ing a barrier or constraint that limits achievement ofgoals (eg clinical administratorsrsquo and financial offi-cersrsquo belief that VR equipment is too expensive toincorporate into mainstream practice)

What has typically been found to be effective basedon SWOT input is a strategy that takes advantage of

the entityrsquos opportunities by employing its strengthsand by proactively addressing threats by correcting orcompensating for weaknesses This paper will begin bybriefly reviewing the oft-discussed topics relating to VRstrengths and weaknesses with illustrations from exist-ing work in the fields of rehabilitation and therapy Dueto space limitations the examples provided are notmeant as an exhaustive listing The more challenginganalysis of opportunities and threats requires an exami-nation of scientific technological medical marketing

Strengths Weaknesses Enhanced Ecological Validity The Interface Challenge 1 Interaction Methods Stimulus Control and Consistency The Interface Challenge 2 Wires and Displays Real-Time Performance Feedback Immature Engineering Process Cuing Stimuli to Support ldquoError-Free Learningrdquo Platform Compatibility Self-Guided Exploration and Independent

Practice Front-End Flexibility Back-End Data Extraction Management Analysis

Visualization Side Effects

Interface Modification Contingent on UserrsquosImpairments

Complete Naturalistic Performance Record Safe Testing and Training Environment Gaming Factors to Enhance Motivation Low-Cost Environments That Can be Duplicated

and Distributed

Opportunities Threats Emerging Tech 1 Processing Power and Graphics

Video Integration Too Few CostBenefit Proofs Could Impact VR

Rehabilitation Adoption Emerging Tech 2 Devices and Wires Aftereffects Lawsuit Potential Emerging Tech 3 Real-Time Data Analysis and

Intelligence Ethical Challenges The Perception That VR Will Eliminate the Need

for the Clinician Limited AwarenessUnrealistic Expectations

Gaming-Industry Drivers VR Rehabilitation with Widespread Intuitive

Appeal to the Public Academic and Professional Acceptance Close-Knit VR Rehabilitation Scientific and

Clinical Community Integration of VR with Physiological Monitoring

and Brain Imaging Telerehabilitation

Figure 1 Summary of a SWOT analysis for VR rehabilitation and therapy

Rizzo and Kim 121

and attitudinal trends that may well be open to variedinterpretations by readers depending on their experi-ences and resources This structured examination of thefactors relevant to the current status and future of VRrehabilitation will be unlikely to produce a final answerthat readers will consensually agree upon But we dohope to stir the visionary pot enough to stimulate somecreative pondering of these issues that will linger on abit as you consider this vital and meaningful VR applica-tion area

In the following discussion the term rehabilitation isdefined broadly as a general descriptor to refer to boththe assessment and treatment of impairments in humanphysical cognitive or psychological functioning Im-pairment will refer to either (1) a loss of existing abilitydue to injury a disease process mental disorder or insome cases the aging process or (2) a failure to displayage-based normative abilities due to a specified develop-mental or learning disability

2 VR Rehabilitation Strengths

21 Enhanced Ecological Validity

Traditional clinical rehabilitation methods havebeen criticized as limited in the area of ecological valid-ity that is the degree of relevance or similarity that atest or training system has relative to the ldquorealrdquo worldand in its value for predicting or improving ldquoeverydayrdquofunctioning (Neisser 1978) Adherents of this viewchallenge the usefulness of analog tasks for addressingthe complex integrated functioning that is required forsuccessful performance in the real world A primarystrength that VR offers rehabilitation is in the creationof simulated realistic environments in which perfor-mance can be tested and trained in a systematic fashionBy designing virtual environments that not only ldquolooklikerdquo the real world but actually incorporate challengesthat require real-world functional behaviors the ecolog-ical validity of rehabilitation methods could be en-hanced As well within a VE the experimental controlrequired for rigorous scientific analysis and replicationcan still be maintained within simulated contexts that

embody the complex challenges found in naturalisticsettings Thus VR-derived results could have greaterpredictive validity and clinical relevance for the chal-lenges that patients face in the real world

A number of examples illustrate efforts to enhancethe ecological validity of assessment and rehabilitationby designing VEs that are replicas of relevant archetypi-cal functional environments This has included the cre-ation of virtual cities (Brown Kerr amp Bayon 1998Costas Carvalho amp de Aragon 2000) supermarkets(Cromby Standen Newman amp Tasker 1996) homes(Pugnetti et al 1998 Rose Attree Brooks amp An-drews 2001) kitchens (Christiansen et al 1998 Da-vies et al 2002) school environments (Stanton Fore-man amp Wilson 1998 Rizzo Bowerly et al 2002)workspacesoffices (McGeorge et al 2001 Schultheisamp Rizzo 2002) rehabilitation wards (Brooks et al1999) and even a virtual beach (Elkind RubinRosenthal Skoff amp Prather 2001) While these envi-ronments vary in their level of pictorial or graphic real-ism this factor may be secondary in importance relativeto the actual activities that are carried out in the envi-ronment for determining their value from an ecologicalvalidity standpoint Since humans oftentimes display ahigh capacity to ldquosuspend disbelief rdquo and respond as ifthe scenario were real it could be conjectured that theldquoecological valuerdquo of a VR task may be well supportedin spite of limited graphic realism and less immersion(such as in flat-screen systems) In essence as long asthe VR scenario resembles the real world possesses de-sign elements that replicate key real-life challenges andthe system responds well to user interaction then eco-logical validity would likely be enhanced beyond exist-ing analog approaches Evidence to support this viewcan be drawn from clinical VR applications that addressanxiety disorders While a number of the successful VRscenarios designed for exposure-based therapy of spe-cific phobias would never be mistaken for the realworld clients within these VEs still manifest physiologi-cal responses and report subjective units of discomfortlevels that suggest they are responding as if they are inthe presence of the feared stimuli (Wiederhold amp Wied-erhold 1998) As well the extinction of the fear re-


sponse that occurs in the VE is often seen to generalizeto the non-VR world and thus provides evidence forthe ecological validity of this form of treatment (Glantzet al 2003)

22 Stimulus Control and ConsistencyThat Supports Repetitive andHierarchical Delivery

One of the cardinal strengths of any advancedform of simulation technology involves the capacity forsystematic delivery and control of stimuli In fact onecould conjecture that the basic foundation of all humanresearch and clinical methodology requires the system-atic delivery and control of environmental stimuli andthe subsequent capture and analysis of targeted behav-iors In this regard an ideal match appears to exist be-tween the stimulus-delivery assets of VR simulation ap-proaches and rehabilitation requirements Much as atank simulator can provide combat testing and trainingVEs can be developed to present simulations that assessand rehabilitate human physical cognitive and psycho-logical processes under a range of stimulus conditionsthat are not easily controllable in the real world ThisldquoUltimate Skinner Boxrdquo asset can be seen to providevalue across the spectrum of rehabilitation approachesfrom analysis at an analog level targeting componentcognitive processes (eg selective attention perfor-mance contingent on varying levels of stimulus-intensityexposure) to the complex orchestration of more molarfunctional behaviors (eg planning initiating andphysically performing the steps required to prepare ameal in a chaotic setting) Although traditional flat-screen computer-based testing and training tools alsooffer these assets it is our view that the added value forusing VR resides in the capacity for systematic stimulusdelivery embedded within immersive simulations offunctional real-world environments

This strength can also be seen to allow for the hierar-chical delivery of stimulus challenges across a range ofdifficulty levels In this way an individualrsquos rehabilita-tion can be customized to begin at a stimulus challengelevel most attainable and comfortable for that person

with gradual progression of difficulty level based on per-formance gains For example on the analog level Yangand Kim (2002) created a motion training system inwhich subjects started with a simple 1D translationtask and later moved to more complex 6-degrees-of-freedom motion tasks With such hierarchical stimu-lus challenges subjects displayed performance im-provements equivalent to real-world training Formore complex integrated behavior the assessment ofdriving skills following traumatic brain injury is oneexample where individuals may begin at a simplisticlevel (ie straight nonpopulated roads) and gradu-ally move along to more challenging situations (iecrowded highways) (Schultheis amp Mourant 2001)Such stimulus-control assets provide the opportunityto identify modify and train individual performancestrategies at various hierarchical levels of challengewithin a VE As well the successful execution ofmany everyday activities requires the integration of avariety of cognitive and motor functions and subse-quent component evaluation of these complex behav-iors is often challenging to clinicians and researchersWith this powerful capacity for stimulus controlwithin a VE the impact of specific patient assets andlimitations may be better isolated assessed and reha-bilitated A good illustrative example of this can beseen in Rizzo Bowerly et al (2002) with a VRclassroom that was designed to systematically presentdistractions while children diagnosed with attentiondeficit hyperactivity disorder attempted to focus on avigilance task within the classroom Substantial degra-dations in attention performance and increases in mo-tor hyperactivity were seen in these children (com-pared to normal controls) when stimulus distractionstypically found in real classrooms were systematicallyintroduced

23 Real-time Performance Feedback

Performance feedback as to the status and out-come of a response is generally accepted to be necessaryfor most forms of learning or skill acquisition and isequally essential to the learning process that underlies

Rizzo and Kim 123

rehabilitation (Sohlberg amp Mateer 2001) While feed-back can be presented in a VE to signal performancestatus in a form that wouldnrsquot naturally occur in the realworld (eg a soft tone occurring after a correct re-sponse) more relevant or naturalistic sounds can also becreatively applied to support response calibration andenhance the perceived realism of the scenario For ex-ample in an Internet-delivered VR application designedto help children with learning disabilities practice escapefrom a house fire (Strickland 2001) the sound of asmoke-detector alarm raises in volume as the child getsnear to the firersquos location As the child successfully navi-gates to safety the alarm fades contingent on her choos-ing the correct escape route

The potential value of virtual-performance feedbackfor rehabilitation applications can be seen from appli-cations designed to support physical therapy in adultsfollowing a stroke (Deutsch Latonio Burdea ampBoian 2001 Jack et al 2001) These applicationsuse various glove and ankle interface devices thattranslate the userrsquos movements into a visible andsomewhat relevant activity that is presented graphi-cally on a flat-screen display For example in one ap-plication as the user performs a prescribed hand exer-cise designed to enhance fractionation (independenceof finger motion) the image of a hand appears on thedisplay playing a piano keyboard reflecting the ac-tual hand movements of the client In a similar appli-cation the appropriate hand movement moves aldquowiperrdquo that serves to reveal an interesting picturealong with a display of a graphic rendering of a per-formance meter representing range of movementThese features serve not only as mechanisms for pro-viding feedback regarding the ongoing status of tar-geted movement but also could serve as motivatorsResults from this lab with stroke patients presentedin a series of seven case studies reported positive re-sults for rehabilitating hand performance acrossrange speed fractionation and strength measures(Jack et al) In one noteworthy case functional im-provement was reported in a patient who was able tobutton his shirt independently for the first time post-stroke following two weeks of training with the VRhand interface As well by making the repetitive and

often boring work of physical therapy exercise moreinteresting and compelling patients reported en-hanced enjoyment leading to increased motivation

24 Cuing Stimuli to SupportldquoError-Free Learningrdquo

The capacity for dynamic stimulus delivery andcontrol within a VE also allows for the presentationof cuing stimuli that could be used for ldquoerror-freerdquolearning approaches in rehabilitation-training scenar-ios This asset underscores the idea that in some casesit may not be desirable for VR to simply mimic realitywith all its incumbent limitations Instead stimulusfeatures that are not easily deliverable in the realworld can be presented in a VE to help guide andtrain successful performance In this special case ofstimulus delivery cues are given to the patient priorto a response in order to help guide successful error-free performance Error-free training in contrast totrial-and-error learning has been shown to be suc-cessful in a number of investigations with such diversesubjects as pigeons to persons with developmentaldisabilities schizophrenia as well as a variety of CNSdisorders (see Wilson amp Evans 1996 for review)This asset can also be harnessed to provide immediateperformance feedback to users contingent on the sta-tus of their efforts Such automated delivery of feed-back stimuli can appear in graded (degree) or abso-lute (correctincorrect) forms and can be presentedvia anymdashor multiplemdashsensory modalities (thoughmainly audio visual tactile are used) depending onthe goals of the application and the needs and sensorycapabilities of the user For example Brooks et al(1999) reported success with a severely amnesticstroke patient using an error-free VR training ap-proach for wayfinding in a rehabilitation-ward VEthat produced positive transfer to the real ward Har-rison Derwent Enticknap Rose amp Attree (2002)also reported mixed results with the use of cuingstimuli in a VR system designed to train maneuver-ability and route finding in novice motorized-wheelchair users


25 Self-Guided Exploration andIndependent Practice

Independent self-assessment and ldquohome-basedrdquoskills practice by clients are common components ofmost forms of rehabilitation Generally it is acceptedthat having clients do ldquohomeworkrdquo will promote gener-alization of skills learned in treatment proper to every-day behavior The widespread increase in access topersonal computing over the last decade has also en-couraged the autonomous use of computerized self-helpsoftware by clients As such it is likely that the indepen-dent use of VR will also become more common as ac-cess to systems and software expands in the future Not-withstanding the potential for shoddy VR applicationsto reach the marketplace with little evidence to supporttheir efficacy or value the option for independent VRuse (when guided by an appropriate professional) can beviewed as a strength for a number of reasons Whencompared with existing flat-screen computerized testingand training formats VR is distinguished by its capacityto provide higher levels of both immersion and interac-tivity between the user and the VE These unique fea-tures are seen to enhance the suspension of disbeliefrequired to generate a sense of presence within the VEWhen this psychological state of presence occurs it isconjectured to create a user experience that may influ-ence task performance (Sadowski amp Stanney 2002)This user experience may produce behaviors that aredifferent from what typically occurs in persons undergo-ing traditional testing and training due to the userrsquosattention being more occupied ldquowithinrdquo the VE Aswell the user experience may be less self-conscious dueto the perceived removal of the test administrator fromthe immediate personal and attentional space This ex-perience could provide a unique qualitative window intohow people perform tasks when operating in a moreindependent and autonomous fashion For example ifclients were allowed to freely interact within a functionalVE (ie office mall home etc) that contained verysubtle test challenges the recording and later observa-tion of more naturalistic client behaviors would be pos-sible This could include observing how individualizedcompensatory or problem-solving strategies are sponta-

neously employed when challenged with a complex situ-ation As well this may also be of value for monitoringdecision making and risk taking in the assessment ofpotentially hazardous real-world skills in a VE such asdriving an automobile

26 Interface Modification Contingenton Userrsquos Impairments to SupportAccess to Rehabilitation

Limitations still exist in fostering truly naturalisticVR interaction with current 3D user-interaction meth-ods (Bowman Kruijff LaViola amp Poupyrev 2001)However for certain populations with sensorimotorimpairments existing 3D UI tools can still support ac-cess to rehabilitation in VR beyond what is possible withtraditional non-VR methods Oftentimes in rehabilita-tion permanent impairments in one domain of func-tioning may interfere with the testing and training ofanother set of functions that potentially could benefitfrom treatment For example one of the current chal-lenges in cognitive rehabilitation concerns the effectiveadaptation of testing and training methods by clientswith significant sensory andor motor impairmentsWhen such adaptations are attempted the question of-ten arises as to how much a clientrsquos performance reflectscentrally based cognitive dysfunction versus artifacts dueto more peripheral sensorimotor impairments VR offerstwo ways in which this challenge may be addressed inthe testing and training of cognitive and everyday func-tional abilities in persons with sensorimotor impair-ments

One approach places emphasis on the design ofadapted human-computer interface devices in a VE topromote usability and access The thoughtful integra-tion of adapted interface devices between the personand VR system could assist those with motor impair-ments to navigate and interact in rehabilitative VR ap-plications (beyond what might be possible in the realworld) Such interface adaptations may support actua-tion by way of alternative or augmented movementspeech expired air and tracked eye movement and byway of neurofeedback-trained biosignal activity (BarrettMcCrindle Cook amp Booy 2002) These devices while

Rizzo and Kim 125

admittedly ldquounnaturalrdquo allow patients to interact be-yond what their physical impairments allow One basicexample involves the use of a gaming joystick to navi-gate in a VE that was found effective for teaching way-finding within a VE modeled after an amnestic clientrsquosrehabilitation unit (Brooks et al 1999) These authorspartially attributed the observed positive training effectsto the patientrsquos capability for quicker traversing of theVE using a joystick compared to what her ambulatoryimpairments would allow in the real environment Thisstrategy by minimizing the impact of peripheral impair-ments on performance allowed for centrally based per-formance components to be more efficiently trained

A second approach to this challenge has been to tailorthe sensory modality components of the VE around theneeds of the personsrsquo impairments The few efforts inthis area have mainly attempted to build simulatedstructures for persons with visual impairments by theuse of enhanced 3D sound (Lumbreras amp Sanchez2000) and haptic stimuli (Connor Wing HumphreysBracewell amp Harvey 2002 Lahav amp Mioduser 2002)For example Lumbreras and Sanchez aiming to designcomputer games for blind children created a 3D audioVR system referred to as ldquoAudioDOOMrdquo In this appli-cation blind children use a joystick to navigate themazelike game environment exclusively on the basis of3D audio cues (ie footstep sounds doors that ldquocreakrdquoopen echoes etc) while chasing ldquomonstersrdquo aroundthe environment Following varied periods of time inthe audio VE the children are then given Legos to con-struct their impression of the structure of the layoutThe resulting Lego constructions are often noteworthyin their striking resemblance to the actual structure ofthe audio-based layout of the maze Children using thissystem (who never actually have seen the physical visualworld) often appear to be able use the 3D sound cues tocreate a spatial-cognitive map of the space and then ac-curately represent this space with physical objects (ieLegos clay sand) Examples of some of these construc-tions are available on the Internet (httpwwwdccuchileclmlumbreraudiodoomaudiodoomhtml)While tested mainly with children it is possible to con-ceive of such 3D audio-based environments as providing

platforms for assessment and rehabilitation of personswith visual impairments at any age

27 Complete NaturalisticPerformance Record

The review of a clientrsquos performance in any reha-bilitation activity typically involves examination of nu-meric data and subsequent translation of that informa-tion into graphic representations in the form of tablesand graphs Sometimes videotaping of the actual eventis used for a more naturalistic review and for behavior-rating purposes These methods while of some valueare typically quite labor-intensive to produce and some-times deliver a less than intuitive method for visualizingand understanding a complex performance recordThese challenges are compounded when the goal of thereview is to provide feedback and insight to clientswhose cognitive impairments may preclude a usefulunderstanding of traditional forms of data presenta-tion VR offers the capability to capture and review acomplete digital record of performance in a virtualenvironment from many perspectives For exampleperformance in a VE can be later observed from theperspective of the user from the view of a third partyor position within the VE and from what is some-times termed a ldquoGodrsquos-eye viewrdquo from above thescene with options to adjust the position and scale ofthe view This can allow a client or therapist to ob-serve the performance from multiple perspectives andrepeatedly review the performance Options for thisreview also include the modulation of presentation asin allowing the client to slow down the rate of activ-ity and observe each behavioral step in the sequencein slow motion

28 Safe Testing and TrainingEnvironment which Minimizes Risksdue to Errors

As alluded to in the VR driving example pre-sented above when developing certain functionallybased assessment and rehabilitation approaches onemust consider the possibility of safety risks that may


occur during activities designed to test and train abili-ties in the real world Driving would probably repre-sent one of the more risk-laden activities that a clientwith cognitive andor physical impairments wouldundertake in order to achieve functional indepen-dence However even simple functional activities canlead to potential injury when working with personshaving CNS-based impairments Such potential riskscan be seen in the relatively ldquosaferdquo environment of akitchen (ie burns falls getting cut with a knife) aswell as in more naturally dangerous situations such asstreet crossing the operation of mechanicalindustrialequipment and driving a motor vehicle Additionallythe risk for clienttherapist injury and subsequent liabil-ity concerns may actually limit the functional targetsthat are addressed in the rehabilitation process Theseldquooverlookedrdquo targets may actually put the client at risklater on as they make their initial independent efforts inthe real world without having such targets addressedthoroughly in rehabilitation

Thus far this asset has served as a driving force forVR-system design and research with clinical and ldquoat-riskrdquo normal populations Such applications includestreet crossing with unimpaired children (McComasMacKay amp Pivak 2002) with populations with learn-ing and developmental disabilities (Strickland 2001Brown et al 1998) and with adult traumatic-brain-injury groups with neglect (Naveh Katz amp Weiss2000) kitchen safety (Rose Brooks amp Attree 2000)escape from a burning house with autistic children(Strickland 2001) preventing falls with at risk elderly(Jaffe 1998) use of public transportation (Mowafty ampPollack 1995) and driving with a range of clinical pop-ulations (Rizzo Reinach McGehee amp Dawson 1997Liu Miyazaki amp Watson 1999 Schultheis amp Mourant2001) In addition to the goal of promoting safe perfor-mance in the real world some researchers have reportedpositive results for building a more rational awareness oflimitations using a VR approach For example Davis ampWachtel (2000) have reported a number of instanceswhere older adults poststroke had decided not to con-tinue making a return to driving a primary immediategoal after they had spent time in a challenging VR driv-ing system

29 Gaming Factors to EnhanceMotivation

Plato is reputed to have said ldquoYou can discovermore about a person in an hour of play than in a year ofconversationrdquo (cited in Moncur amp Moncur 2002) Thisancient quote has particular relevance for VR rehabilita-tion applications Observing andor quantifying a per-sonrsquos approach or strategy when participating in a struc-tured game-based activity may provide insight intofunctioning similar to what is acquired with traditional(yet less meaningful) standard performance assessmentsThe capacity for a person to become engaged in a gam-ing task and become less focused on the fact that theyare being ldquotestedrdquo may provide a purer gauge of natu-ralistic ability As well another more compelling clinicaldirection may involve leveraging gaming features andincentives for the challenging task of enhancing motiva-tion levels in clients participating in rehabilitation Infact one possible factor in the mixed outcomes found inrehabilitation research may be in part due to the inabil-ity to maintain the clientsrsquo motivation and engagementwhen confronting them with a repetitive series of train-ing challenges whether they be cognitive or physicalactivities Hence the integration of gaming features inVR-based rehabilitation systems to enhance client moti-vation is viewed as a useful direction to explore

Thus far the integration of gaming features into a VEhas been reported to enhance motivation in adult clientsundergoing physical and occupational therapy followinga stroke (Jack et al 2001 Kizony Katz amp Weiss2003) As well Strickland (2001) reports that childrenwith autism were observed to become very engaged inthe VR safety-training applications she has developedthat incorporate gaming features Further anecdotal ob-servations suggest that children diagnosed with atten-tion deficit hyperactivity disorder often have a fascina-tion for the type of stimulus environments that occurwith computervideo games (Greenhill 1998) Parentsare often puzzled when they observe their children fo-cusing on video games intently while teacher reportsindicate inattention in the classroom Additionally inthe first authorrsquos clinical experience it was observed thatsome of the young adult traumatic-brain-injury clients

Rizzo and Kim 127

who had difficulty maintaining concentration on tradi-tional cognitive rehabilitation tasks would easily spendhours at a time playing the computer game SimCityThese observations suggest that designers of rehabilita-tion tasks can benefit from examining the formulas thatcommercial game developers use in the creation of in-teractive computer games These formulas govern theflow and variation in stimulus pacing that provide link-age to a progressive reward and goal structure Whendelivered within a highly interactive graphics-rich envi-ronment users are observed to become extremely en-gaged in this sort of game play Neuroscience researchin the area of rapid serial visual presentation (RSVP)may provide some scientific insight into the human at-traction to these fast-paced-stimulus environments Inthis regard Biederman (2002) suggests that a gradientof opiate-like receptors in the portions of the cortex in-volved in visual auditory and somatosensory perceptionand recognition drives humans to prefer experiencesthat are novel fast immersive and readily interpretedThis may partly underlie the enhanced motivation thatis observed for the types of activities that are presentedin interactive gaming environments While many reasonsmay contribute to the allure of current interactive com-puter gaming a proper discussion of these issues is be-yond the scope of this article However the potentialvalue of gaming applications in general education andtraining is increasingly being recognized An excellentpresentation of these topics can be found in Prensky(2001) along with an extensive gaming bibliographythat is available at the Digiplay Initiative (2002)

210 Low-Cost FunctionalEnvironments That Can be Duplicatedand Distributed

Rather than relying on costly physical mock-ups ofrehabilitation environments VR offers the capacity toproduce and distribute identical ldquostandardrdquo environ-ments Within such digital rehabilitation scenarios nor-mative data can be accumulated for performance com-parisons needed for diagnostics and for trainingpurposes While the initial cost to produce an environ-ment may be high this financial outlay could be dissi-

pated with cost sharing by professionals adopting theenvironment In view of this the future evolution of VRin rehabilitation will likely be driven by three key ele-ments First continuing advances in the underlying en-abling technologies necessary for VR delivery alongwith concomitant hardware-cost reductions will allowVR to become more available and usable by indepen-dent clinicians and researchers Second this potentialfor increased access and the impact of market forces willresult in further development of new VR applicationsthat target a broader range of clinical and research tar-gets And finally continued research aimed at determin-ing reliability validity and utility will help establish cer-tain VR applications as mainstream rehabilitation toolsContingent upon the occurrence of these events it willbe possible that future rehabilitation professionals willbe able to purchase a VR system that provides themwith a suite of environments (ie home classroom of-fice community etc) within which a variety of testingand training tasks will be available This has already oc-curred in the area of VR anxiety-disorder applicationswith no fewer than three companies marketing systemsin this manner Internet access to libraries of download-able VR scenarios will become a likely form of distribu-tion Data-mining scoring and report-writing featureswill also become available similar to what currently ex-ists with many standardized computer-administeredpaper-and-pencil tests As well highly flexible ldquofront-endrdquo interface programs will allow clinicians and re-searchers to modify stimulus deliveryresponse captureparameters within some VEs and tailor system character-istics to more specifically meet their targeted purposesThis level of availability could provide professionals withunparalleled options for using and evolving standard VRapplications in the service of their clients and for scien-tific aims

3 VR Rehabilitation Weaknesses

31 The Interface Challenge 1Interaction Methods

Enhanced ecological validity has already beenraised as an important strength for VR-based rehabilita-


tion However before this vision can be fully reachedconceptual and technological advances need to occur inthe area of 3D user-interface devices and techniquesFrom a human-computer interaction perspective a pri-mary concern involves how to design more effectiveefficient and easily learnable methods for human inter-action with such complex systems Current methods arestill limited in the degree to which they allow users tonaturalistically interact with the assessment and rehabili-tation challenges presented in a VE Rehabilitation de-velopers are often constrained to use existing hardwarethat often falls short of the aim to foster natural interac-tion This is a significant problem since in order forpersons with cognitive andor physical impairments tobe in a position to benefit from VR applications theyshould ideally be able to easily learn how to navigateand interact within a VE in a manner similar to howthey do it in the real world Many modes of VR interac-tion (ie wands joysticks 3D mice etc) while easilymastered by unimpaired users could present problemsfor those with cognitive or physical impairments A casecan be made that short of fostering truly realistic natu-ralistic interaction perhaps interaction methods basedon ldquomagicrdquo that give the user ldquosuprahumanrdquo interactionabilities are a viable option (Bowman et al 2001)However these methods would need to be highly learn-able and for some rehabilitation applications devicesmight also have to be custom-made to suit the specialneeds and impairments of patients This would requireextensive usability testing even before the clinical effi-cacy of the scenario could begin to be evaluated Even ifpatients are capable of using a less natural interactionmethod at a basic level the extra nonautomatic cogni-tive effort required to interactnavigate could serve as adistraction and limit the assessment and rehabilitationprocesses In this regard Psotka (1995) hypothesizesthat facilitation of a ldquosingle egocenterrdquo found in highlyimmersive interfaces would serve to reduce ldquocognitiveoverheadrdquo and thereby enhance information access andlearning

This is representative of the larger general problemof designing usable interfaces for all VR applicationsDespite some recent progress in interaction modeling(Bowman et al 2001) finding the best interface

method for a given application usually requires costlyand time-consuming usability testing Other major ob-stacles for designing usable interfaces for VR-based re-habilitation include the rapid changes in hardware capa-bilities device availability cost and the lack of a maturemethodology in interaction design The situation is of-ten compared to the case of 2D desktop interfaceswhere a mature interface methodology has emergedover the last 30 years using devices that are standard-izedfixed (mouse keyboard monitor) (Preece Rog-ers amp Sharp 2002) With the absence of such an estab-lished design methodology we are still limited to a trial-and-error exploratory approach to VR interactiondesign Such a method adds another layer of challengesfor rehabilitation professionals who have little familiaritywith usability testing Additionally managed-health-caredollars are scarce for supporting this type of essentialthough less sexy usability research with clinical popula-tions This is an area that needs the most attention inthe current state of affairs for VR rehabilitation andbetter multidisciplinary collaboration in application de-velopment may be a key element for future success

32 The Interface Challenge 2 Wiresand Displays

Many devices that are required to operate a VRsystem or to track user behavior require wires and vari-ous connectors that are a source of distraction and in-convenience Wires constrain interaction both mentallyand physically and complex motion can result in theuser getting tangled in wires and cables that limit usabil-ity and could create safety hazards Similarly after allthe years of advancements in the field of VR an inex-pensive technology for head-mounted display (HMD)systems with near-human vision quality has yet to arriveHMDs are still cumbersome mostly tethered and pro-vide only limited resolution and field of view Provisionof stereoscopy within an HMD is still problematic dueto the conflict between flat displays and human eye ac-commodation and convergence factors that sometimesresults in user eyestrain headaches and other side ef-fects Fully immersive projection displays (ie CAVEPowerwalls Immersadesks) may offer better visual char-

Rizzo and Kim 129

acteristics yet remain a very expensive option that re-duces pragmatic availability for rehabilitation uses 3Dsound display technology has seen much progress in thelast 20 years and control of the azimuth (left and right)of sound stimuli has become quite effective (Duda2004) However the 3D sound quality produced fromthe general-purpose sound cards is at its best with theuse of a headphone instead from a set of speakers (nottethered) This is because the head-related transfer func-tions used in the sound cards are usually sampled withmicrophones located in the two ears of a human headmodel This in turn makes the use of multichannelspeakers difficult because the synthesized sound is basedon two channels (two-speaker configurations can beused with less accurate effect) Moreover it is still diffi-cult to produce sound effects in terms of the elevationand range Even though inexpensive wireless head-phones are available the fact that headphones (or ear-phones) must be used at all in addition to the HMD issometimes a nuisance for users

Progress has also been relatively slow in display tech-nology for addressing other sensory modalities such astouch and olfaction For example force-feedback hapticdevices require a large mechanical structure and thisposes many challenges in terms of usability distractionand costs The available commercial products in thisarea also mainly target only proprioceptive sensationwith limited degrees of freedom using expensive exo-skeletal devices (Cybergrasp 2004) ldquoPhantom-typerdquodevices (Massie amp Salisbury 1994) while showingsome value for surgical simulation (MacFarlane RosenHannaford Pellegrini amp Sinanan 1999) have suchconstrained functionality that it is tough to justify thecosts in view of the limited rehabilitative targets thatthey can address However researchers with the re-sources for such force-feedback equipment have re-ported successful implementation with clinical groupsusing the Reach-In system (Broeren Bjorkdahl Pas-cher amp Rydmark 2002) and with custom-built devicesfor hand and ankle rehabilitation (Burdea PopescuHentz amp Colbert 2000) For tactile sense simulationthe research has primarily focused on techniques to re-create the texture of virtual surfaces using special devices

and materials such as the piezo-electric elements (Hirotaamp Hirose 1995 Allison Okamura Dennerlein ampHowe 1998 Burdea 1996 Ikei amp Stiratori 2002)These systems typically are applied to a relatively smallskin area such as the fingertip and find very low utility inactual system deployment Proposals to use small vibra-tory devices for tactile feedback applied to a larger skinarea have been made in several application contexts(Tan amp Pentland 1997 Jang Yang amp Kim 2002)but results on their utility and usability are still pre-liminary In general most precision haptictactiledevices are still too costly to find their way into main-stream rehabilitation and the troubling thought isthat there does not seem to be a visible breakthroughin these areas in the near future This is unfortunatesince better touch simulation is especially desirablefor motor rehabilitation and for creating applicationsfor patients with visual and auditory impairments(Lahav amp Mioduser 2002)

Tracking devices and sensors are one of the funda-mental technologies for any VR system yet still presentconsiderable usability cost and accuracy limitationsEven though wireless tracking methods have becomeavailable they are still expensive and not accurateenough Magnetic trackers perhaps the most populartype either require a specially made magnetic-field-freeoperating room or a cumbersome calibration process toachieve a reasonable accuracy Inertial trackers are proneto drift and error accumulation after some extendedperiod of use Ultrasonic and optical methods have line-of-sight and occlusion problems Accurate marker-basedtracking systems are very expensive low in usability(eg users must wear special suits) and thus are findinguse mainly for animation production and motion cap-ture and not for everyday use as is often required inrehabilitation Real-time marker-less vision-based track-ing is still in early stages of development for 6DF appli-cations (Wren Azarbayejani Darrell amp Pentland 1997Cohen Li amp Lee 2002) but may provide useful op-tions in the future In essence significant advances arestill needed to produce low-cost and accurate trackingtechnology required for more effective VR rehabilitationsystems


33 Immature Engineering Process forVR-Based Rehabilitation Systems

While often touted as the media of the next gener-ation virtual reality still has not caught up with themainstream of content development let alone for VR-based rehabilitation applications One of the major ob-stacles is the lack of models methodologies and toolsfor VR systemcontent development Building testingand maintaining a VR-based rehabilitation application isundoubtedly a very complex process Developers mustintegrate disparate bodies of knowledge in both engi-neering and rehabilitation that include such subareas astracking displays interaction computer graphics sim-ulation human factors biokinesiology cognitive psy-chology and so forth What makes VR rehabilitation-application development so difficult is that on top ofhaving to tackle traditional computational and logicalchallenges one must also address usability concerns spe-cific to the application its task components and thecharacteristics of the clinical user group The require-ments for a VR application designed to treat fear of fly-ing in an otherwise healthy adult phobic will naturallydiffer substantially from one to teach a Downrsquos Syn-drome teenager how to navigate a supermarket

The system science for VR has not yet reached maturityto efficiently address these challenges (Seo amp Kim 2002)Recent object-oriented VR development tools provideonly abstractions for the system functionalities (ie devicehandling displays etc) Unlike ordinary programmingtasks VR execution and development environments aredifferent not just in the temporal sense but also in thephysical sense Many VR systems have usability problemssimply because developers find it costly and tiring to switchback and forth between the development (eg desktop)and execution environments (eg immersive setup withHMD glove trackers etc) and fail to fully test and con-figure the system for usability Such issues make systemoptimization and cost estimation for building a VR appli-cation very difficult Therefore the perceived cost of aVR application becomes quite high and in most caseswrongly so because with the knowledge and application ofsystem science a cost-effective solution should be foundConsequently the inability to predict overall development

cost remains a major weakness for VR to be proliferated tomany different fields In comparison to game develop-ment VR-based rehabilitation systems tend to be ldquoone-offsrdquo rather than marketed for a mass audience Such anature is more of a reason to have a model for cost estima-tion and for development That is game development mayjustify a large investment due to its large market while aone-of-a-kind VR system usually cannot afford to do soand requires a more targeted systematic approach

34 Platform Compatibility

In order for VR to come into mainstream rehabili-tation practice one basic computational device needs tobe easily configurable to run a variety of applications ina manner akin to the ease of installing and running bothMS Word and Adobe Acrobat on the same machineHowever most virtual-reality applications are not inter-operable This is primarily due to the relatively shorthistory of active VR-based application development Inthe early days (late 80s to mid-90s) most VR applica-tions were developed using Silicon Graphics (SGI)graphics workstations that ran the IRIX operating sys-tem (a variant of the UNIX operating system) SGI wasalso instrumental in developing many useful tools forVR application development including the PerformerOpenGL and Inventor (SGI 2004a) However due totheir high cost and the PC graphics-card revolutionmany developers now have switched to the PC platformThis created initial problems in that there were fewgood development tools equivalent to those available onthe SGI workstations and it took years for VR engineAPI vendors to come up with relatively stable and bug-free versions of their software for PCs For example theWindows version of the very popular Performer becameavailable only in 2003 (SGI 2004b) Consequentlymany interesting and useful early SGI-based VR applica-tions need to be substantially modified in order to beported to the MS Windows environment arguably themost popular operating system in use today The transi-tion from special-purpose graphics workstations to clus-tered PCs for CAVE-type systems (which usually re-quire a form of a multiprocessing system) has onlyrecently begun as the major graphics-card vendors

Rizzo and Kim 131

started to offer the ldquoGen-Lockrdquo feature which can con-nect graphics cards installed on different PCs to worktogether in synchrony Thus the current situation issuch that although we are starting to truly convergetoward using PCWindows as the main developmentplatform there are still many legacy applications that arewritten for other hardware platforms and operating sys-tems Similarly while many developers are making acase for the use of the LINUX operating system veryfew clinical settings are willing to adopt this OS as theyare already beholden to the Microsoft juggernaut

However it is not just the problem of different oper-ating systems and computing hardware but more im-portantly the fact that applications are not written in aflexible and reconfigurable manner VR systems usemany different devices and software including graph-icsvideo-processing cards trackers buttoned devicescameras 3D sound hardware voice-recognition soft-ware monostereo displays and so forth Applicationsthat have been developed for one particular configura-tion of devices often fail to run (under the same com-puting operating environment) if the proper devices(and their drivers) are not available In many situationsit is difficult to duplicate the exact same operating envi-ronment and as such applications need to be able toaccommodate (through software control) similar devices(eg between different graphics cards trackers driverversions display types) For rehabilitation applicationsthe situation should exist where a number of differentdevice configurations can still work with similar effects(eg using wired trackers or wireless vision-based track-ers using tactile devices or without) without requiringthe constant scrutiny of a programmer on site Surelythis presents a problem in effectively maintaining VRsystems which again illustrates the critical need for anengineering-science approach to the whole lifecycle ofVR application development

35 Front-End Flexibility

Rehabilitation therapists and professionals are of-ten not programmers Consequently in order to maxi-mize the usability and subsequent usefulness of a VRrehabilitation program great care needs to be placed on

building an intuitive front-end interface We will go asfar as saying that the rule of thumb should be that themenus options and so forth for adjusting stimulus pa-rameters should be no more complex than that found inMS Powerpoint Unfortunately that is often not thecase with much of the clinical VR software that is beingused in rehabilitation Oftentimes a program is hard-coded so that the clinician can use it only in a ldquoone-size-fits-allrdquo manner or else any adjustments require actuallygoing into the program files and changing lines of codeAs simple as code modifications are to a programmerrequiring nonprogrammer clinicians to do this is often aldquodeal-breakerrdquo To avoid this requires the application ofuser-centered design strategies whereby the ldquouserrdquo inthis case is the clinician While the few commercial VRrehabtherapy developers are now addressing this prob-lem (ie Virtually Better Digital Mediaworks Psychol-ogy Software Tools etc) many university-based VRpackages build these functions in as an afterthoughtSadly many innovative scenarios do not get applied andtested to their full potential after a clinician with littlecomputer-science tech support gets frustrated followinga challenging first start or subsequently when adjust-ments cannot be made easily in the program to suit theneeds of a particular patient

36 Back-End Data ExtractionManagement Analysis Visualization

As with the front-end problem mentioned abovenon-computer-savvy professionals need VR softwarethat spits out performance data automatically and in anintuitive form While this may add cost to the initial de-velopment and consequently is often not well attendedto in clinical applications it is an absolute requirementfor a VR rehabilitation application to be adequately usedand evaluated Most VR rehabilitation applications thatrecord complex performances often produce very largefiles of raw data that then require another program tounravel the metrics that a clinician is interested in Whilethose files of raw output of course have value the nextstep needed to make an application have real usableclinical utility is to also deliver basic summary scorescomparison statistics with accumulated normative data


and intuitive representations of the findings in standardgraphical and even 3D formats It is our view that boththe front-end and back-end weaknesses seen in much ofthe VR rehab software to date is the product of devel-opers with limited resources rushing to simply producea proof of concept collect some quick clinical data andthen apply for more grant money to fix usability prob-lems later As we all know from other application areasthis is usually a more costly approach and even worsemay lead to the program being abandoned in the earlystages of testing out of frustration by the clinical profes-sionals using the application

37 Side Effects

In order for VR to become a safe and usefultool for any application the potential for adverse sideeffects needs to be considered and addressed This isa significant concern as the occurrence of side effectscould limit the applicability of VEs for certain clinicalpopulations Two general categories of VE-relatedside effects have been reported cybersickness and af-tereffects Cybersickness is a form of motion sicknesswith symptoms reported to include nausea vomitingeyestrain disorientation ataxia and vertigo (KennedyBerbaum amp Drexler 1994) Cybersickness is be-lieved to be related to sensory-cue incongruity Thisis thought to occur when there is a conflict betweenperceptions in different sense modalities (auditoryvisual vestibular proprioceptive) or when sensory-cue information in the VE environment is incongru-ent with what is felt by the body or with what is ex-pected based on the userrsquos history of real-worldsensorimotor experience (Reason 1970) Aftereffectsmay include such symptoms as disturbed locomotionchanges in postural control perceptual-motor distur-bances past pointing flashbacks drowsiness fatigueand generally lowered arousal (Rolland Biocca Bar-low amp Kancherla 1995 DiZio amp Lackner 1992Kennedy amp Stanney 1996) The appearance of after-effects may be due to the user adapting to the senso-rimotor requirements of the VE which in most casesis an imperfect replica of the non-VE world Upon

leaving the VE there is a lag in the readaptation tothe demands of the non-VE environment and theoccurrence of aftereffects may reflect these shifts insensorimotor response recalibration The reportedoccurrence of side effects in virtual environments inunimpaired populations varies across studies depend-ing upon such factors as the type of VE programused technical drivers (ie vection response lagfield of view etc) the length of exposure time thepersonrsquos prior experience using VEs active versuspassive movement gender and the method of mea-surement used to assess occurrence (Hettinger 1992Regan amp Price 1994 Kolasinski 1995) In a reviewof this area Stanney and colleagues (1998) targetfour primary issues in the study of VE-related sideeffects that may be of particular value for guidingfeasibility assessments with different clinical popula-tions These include ldquo(1) How can prolonged expo-sure to VE systems be obtained (2) How can after-effects be characterized (3) How should they bemeasured and managed (4) What is their relationshipto task performancerdquo (p 6) These questions are par-ticularly relevant to developers of clinical VEs asthese systems are primarily designed to be used bypersons with some sort of defined diagnosis or im-pairment It is possible that clinical users may haveincreased vulnerability and a higher susceptibility toVE-related side effects and ethical clinical vigilanceto these issues is essential Particular concern may benecessary for neurologically impaired populationssome of whom display residual equilibrium balanceperception and orientation difficulties It has alsobeen suggested that subjects with unstable binocularvision (which sometimes can occur following strokesTBI and other CNS conditions) may be more sus-ceptible to postexposure visual aftereffects (Wann ampMon-Williams 1996) These issues should be investi-gated further in order to determine what effectivemethods exist to reduce side effects that could limitthe feasibility of VEs for applications with clinicalpopulations An extended discussion of clinical datain this area can be found in Rizzo Schultheis ampRothbaum (2002)

Rizzo and Kim 133

4 VR Rehabilitation Opportunities

41 Emerging Advances in VRTechnology 1 Processing Power andGraphicsVideo Integration

Providing visual realism is undoubtedly an impor-tant component in developing an effective VR rehabili-tation environment Although it is still difficult to ex-actly quantify what constitutes a minimum level ofrealism the continuing revolution in consumer-levelcomputer-graphic technology has helped the cause ofVR for many applications including the rehabilitationdomain The level of possible detail in visual realism canbe indirectly measured by the capabilities of the polygonand texture-processing power of the graphics hardwareThis figure the number of polygons that can be ren-dered in a scene in real time has increased almost expo-nentially during the past several years For example theoriginal PlayStation released in 1995 rendered300000 polygons per second while Segarsquos Dreamcastreleased in 1999 was capable of 3 million polygons persecond The PlayStation 2 renders 66 million polygonsper second while the Xbox set a new standard render-ing up to 300 million polygons per second (Xbox2004) Thus the images on todayrsquos $200 game con-soles rival or surpass those available on the previous de-cadersquos $50000 computers (Laird 2001)

Textures and images have been used effectively toenhance visual realism and the graphics-processing capa-bilities on the PC level have also increased dramaticallyover the past few years with this trend expected to con-tinue in the future The days of up to 128 MB of dedi-cated onboard texture memory (128 128-sized tex-ture is about 64 KBs and 128 MB texture memory canhold 2000 of these) are already looming and what weonce called the graphics card or VGA controllers arenow becoming a separate dedicated computing unit forgraphics Such graphics processing units (GPUs) arenow programmable and thus pixel-and texel-specificcomputations can be customized for enhanced realismand real-time performance (Fernando amp Kilgard 2003)This makes image-based rendering such as view morph-ing and environment maps (in addition to using tradi-tional textured 3D polygons) an attractive approach for

enhancing pictorial realism Many other dedicated com-putational modules on todayrsquos graphics board will con-tinue to make real-time shadows and realistic light ef-fects (such as ray casting) possible These light effectsare very important for constructing images tuned to thehuman visual system Stereoscopic support multichan-nel outputs and multiboard synchronization are be-coming standard or popular features With the popular-ity of PC-based games PC architectures and data bussystems are being redesigned and customized for theexchange of a large amount of model and image databetween the CPU memory and the graphics sub-system One of the promising trends in interactivegraphics is the resurgence of computer vision tech-niques an excellent alternative to using wired sensors totrack user behavior Computer vision requires consider-able image processing and the ever increasing power ofCPUs and GPUs is also making vision-based techniquesmore viable

42 Emerging Advances in VRTechnology 2 Devices and Wires

While the issue of cumbersome displays with lim-ited capabilities and the design of usable interfaces re-main a challenge for VR-application developers (andresearchers) two recent developments are very promis-ing The first concerns the emerging advances in displaytechnology driven by general consumer markets Forexample autostereoscopy makes stereo viewing possiblewithout the need to wear any special equipment (iepolarized or active shutter-type glasses) a feature thatcan enhance the overall usability of VR systems TheSharp Corporation has recently unveiled an autostereo-scopic notebook computer based on an LCD parallaxbarrier technology that is only $500 more than the or-dinary notebook computer Moreover such technologycan be combined with digital light projection (DLP)technologies to be applied to larger projection displaysystems Digital television and new types of displaysystems such as plasma TV LCD and DLP will even-tually make advanced digital imagery ubiquitous inhomes with hopefully some ldquospilloverrdquo into clinicalapplications


Another positive development is the strong trend to-ward wireless technology In the context of VR thereare two visible thrusts in this direction One is the al-ready mentioned resurgence of computer vision tech-niques for tracking user motion and for monitoring andinferring user state and intention Computer visiontechniques generally suffer from long computation timedue to the inherent nature of image processing (havingto make a calculation for each pixel) Dedicated hard-ware and fastercheaper CPUs are practically makingthis limitation disappear For example Sony has recentlyintroduced a camera-based interface for the PlayStation2 called the EyeToy for under $50 (EyeToy 2004)Canesta Inc has developed a new solid-state chip thatcan sense 3D objects and process such data in real time(the technology has been applied to implementing avirtual keyboard by tracking human fingers) (Canesta2004) Cheap vision processing will one day enablewireless whole-body tracking (Wren et al 1997 Cohenet al 2002) that will have significant impact on the fea-sibility of physical therapy VR applications Real-timevision processing will also enhance mixedaugmentedreality systems applied to rehabilitation Augmentedreality systems would work quite well for certain reha-bilitation applications by allowing the userrsquos own bodyparts to be seen when interacting with overlaid virtualobjects This would be of value for many areas but es-pecially for physical therapy where this approach couldbe leveraged to enhance the sense of proprioception andpromote hand-eye coordination The second thrust withthe wireless-technology trend is the advent of ubiqui-tous computing Ubiquitous computing advocates thedistribution of processing and sensor elements aroundeveryday living environments so that various objects inthe environment can monitor and respond to us to pro-vide intelligent service (Weiser amp Brown 1996) Whilesuch a society is still a long time in coming efforts inwireless communication are already making an impacton wireless-sensor technology In fact using wirelesstechnology such as Bluetooth Radio Frequency ID(RFID) tags ad hoc networks and so forth it is alreadypossible to unwire various current sensors used in theVR context Advances in this domain if fueled by wide-spread adoption with consumer technology could result

in low-cost tracking sensors that would have significantimpact on the usability of VR in general as well as forrehabilitation applications

43 Emerging Advances in VRTechnology 3 Real-Time Data Analysisand Intelligence

One of the strengths observed for VR rehabilita-tion is the capability for sensing 3D behavioral-actiondata and then presenting feedback regarding ongoingprogress for enhancing learning perhaps via an errorless-learning paradigm Such useful feedback is possible withthe emergence of real-time motion analysis coupledwith direct acquisition of motion data (Baek Lee ampKim 2003) Traditional motion analysis used to be anoff-line and sometimes manual process because the rawdata is usually in video form and such video data pro-cessing is very time consuming and difficult For exam-ple a typical golf-swing motion analysis used to requirea golf professional to manually segment out (using amouse) the relevant features in the video (eg golfclub shoulder line etc) and only then would the com-puter algorithm be able to track motion and produceautomatic analysis data Today various motion sensorsthat can directly collect specific motion profiles are mak-ing their way into the motion and sports science arenaThis could serve as a starting point for designing VRapplications in motor rehabilitation that integrate gam-ing features to enhance motivation Going one step fur-ther from simply analyzing patient data AI techniquescould be applied to make intelligent rehabilitation sug-gestions and perhaps even guide the pacing of stimuluschallenges within the VE contingent on the patientrsquosmotor performance

For rehabilitation domains with a social context vir-tual humans realistic both in appearance and behaviorwill be very important Realistic (in terms of appearanceand motion) virtual synthetic humans are already com-monplace in PC-level games For example current of-ferings in the sports-themed digital gaming arena fea-ture texture-mapped real-life characters that can becontrolled by the user to produce lifelike behavior usingacquired motion data VR applications for targeting psy-

Rizzo and Kim 135

chological processes related to social interaction willrequire dynamic interaction with virtual human charac-ters that are intelligent and autonomous For examplesuch applications would be of value for addressing socialphobia in adults as well as for helping children withautism to learn appropriate social skills This has beenthe goal of artificial intelligence for a long time andeven though producing a software agent with humanintelligence seems insurmountable at this moment thetraditional AI and VR fields are merging to producevirtual characters that are adaptive and convincing formany applications Laird (2001) has been applying ageneral AI architecture called Soar to game enginessuch as the Quake II to create agents that are challeng-ing opponents not because of their superhuman reac-tion times and aiming skills but because of their com-plex tactics or game knowledge This will be animportant component in future VR rehabilitation appli-cations and such approaches have the potential for cre-ating scenarios in which social interactions are targetedThe Sims electronic game series provides an excellentexample of how social interactions can be the basis foran engaging virtual arena (Sims 2004) While develop-ment costs and the lack of processing power preventgames for todayrsquos computers and consoles from exhibit-ing a high level of artificial intelligence that will soonchange Currently developers devote more resources toadvancing a gamersquos graphics technology than to en-hancing its AI However the recent USCICT-developed game Full Spectrum Warrior (ICT 2004)now devotes 60 of processor resources to the AI com-ponent It is likely that within two to three years theemphasis on graphics will have run its course as incre-mental advances lead to only marginal improvements inthe game experience At that point the market driversto create games with higher AI ldquoquotientsrdquo could havesignificant impact on VR rehabilitation applications

44 Gaming-Industry Drivers

There is no doubt that the recent growth in theinteractive gaming-industry arena will continue to drivedevelopments in the field of VR rehabilitation Thegaming-industry-juggernautrsquos growth is evidenced by

the fact that it has now surpassed the Hollywood filmindustry in total entertainment market share and in theUSA sales of computer games now outnumber sales ofbooks (Digiplay Initiative 2002) While the 18ndash24-year-old male population initially comprised the largestgroup of users of commercial interactive computer gam-ing applications this popularity has also extended toother age groups and to females at a rapid pace (Lowen-stein 2002) As such it appears that gaming applica-tions have become a standard part of the ldquodigital home-steadrdquo as delivered on PCs and specific gaming consoles(ie Playstation Xbox etc) From this interactivegaming has become well integrated into the lifestyles ofmany people who at some point may require rehabilita-tive services For this segment of the population famil-iarity with and preference for interactive gaming couldbecome useful assets for enhancing client motivationand engagement when designing VR-based rehabilita-tion tasks

VR therapy and rehabilitation scenarios are also in-creasingly being built off of a variety of software enginesdeveloped by the gaming industry Whether built fromthe bottom up (DMW 2004) or in the form of ldquomodsrdquowhereby sections of a popular game title can be modi-fied to create a new scenario (Robillard BouchardFournier amp Renaud 2003) the graphics and audiooptions available with these systems are fast becomingthe tool of choice for developers Just as the advances ingame-industry-driven graphics cards have helped bringhigh-quality VR rendering to the PC we can expectrehabilitation applications to benefit from the continuedgrowth of this field With further advances it is ex-pected that gaming hardware will soon become a com-mon low-cost platform on which many VR rehabilita-tion applications will be built

45 VR Rehabilitation ApplicationsHave Widespread Intuitive Appealto the Public

As much as developers and scientists working inthe field of virtual reality are cognizant of the challengesand limitations that exist for creating usable applica-tions the general public is still drawn to the idea of us-


ing VR when it is linked to a pressing therapeutic targetRegardless of whether the public interest and excite-ment is due to realistic media and scientific reports or tothe illusions created about the state of VR as presentedin such movies as Lawnmower Man or The Matrix it isgenerally observed that people have an initial favorableview of the concept of VR An example of this can beseen in the growing number of articles and TV reportson VR health-related applications that appear in main-stream media outlets (ie the NewYork Times theWashington Post Tech TV Discovery Channel etc)For better or worse reporters often choose what scien-tific news to cover with the public interest in mind andthis has driven the increasing appearance of VR andtherapyrehabilitation reports in both print media andtelevision Another example that our research group hasnoted is in the enthusiasm seen in participants attendingnon-VR events when an HMD demo is available at abooth in an exhibition hall We have recently set upsuch demonstrations at a wide range of diverse scientificand general non-VR-specific public events and haveconsistently observed a steady stream of participantswaiting in lines eager to try VR While this public inter-est should not be mistaken as a measure of the validityor value of VR this positive ldquoviberdquo can be seen as re-flecting a state of curious acceptance that bodes well forfuture adoption of well-executed applications Howeveroverhyped applications can as well lead to negative VRimpressions if an imbalanced ldquoexpectation to deliveryrdquoratio is created as will be discussed later in theldquoThreatsrdquo section of this paper

46 Academic and ProfessionalAcceptance

There has recently been a noticeable positive shiftin the perception of VR applications in therapy and re-habilitation by mainstream scientists and professionalsWhile once viewed as an ldquoexpensive toyrdquo VR is gradu-ally being accepted as a ldquotoolrdquo that can provide newoptions for how therapy and rehabilitation is done Evi-dence for this can be seen in the growing appearance ofVR articles in mainstream journals along with themeissues devoted to VR and associated technologies (ie

Disability and Rehabilitation Neuropsychological Reha-bilitation Journal of Head Trauma Rehabilitation Psy-chological Inquiry Psychotherapy Theory Research Prac-tice Training) acceptance of papers and symposia atmainstream conferences (APA RESNA INS NANACRM AABT) and in the increased funding by suchorganizations as NIH NIMH NIDA NIDRR and soforth Other indicators include such things as VR beingcited as ldquoone of the emerging areas in the future of neu-ropsychologyrdquo during the presidential address at theNational Academy of Neuropsychology in 2001 and inthe fact that in a poll published in the journal Profes-sional Psychology Research and Practice (NorcrossHedges amp Prochaska 2002) a group of 62 therapyexperts ranked VR and computerized therapies 3rd and5th out of 38 interventions that are predicted to in-crease in the next 10 years Much of this shift in attitudecan be attributed to the highly visible initial clinicalstudies yielding positive results using VR for exposuretherapy in persons with anxiety disorders This applica-tion area is intuitively appealing well matched to theassets available with VR and solid research has consis-tently produced clinical outcomes that support its addedvalue (Riva 2002 Glantz et al 2003 Zimand et al2003) Further signs of mainstream acceptance can beseen by the fact that the oldest and largest psychologicaltest publisher The Psychological Corporation has nowbegun to support RampD for standardized VR test devel-opment (DMW 2004) along with interest growing insimilar rival test and therapy aid publishers As VR tech-nology and application development continues toevolve this trend is expected to continue

47 Close-Knit VR RehabilitationScientific and Clinical Community

The ldquoclosenessrdquo of the community of researchersand clinicians that focus on VR rehabilitation has con-tinued to evolve Perhaps this is partly due to an innatehuman drive to form alliances with others of similar in-terests and especially so when the interest area is novelrisky and still seeking credibility from the mainstreamRegardless of the underlying reason evidence for thisgrowing close-knit community can be seen in the num-

Rizzo and Kim 137

ber of conferences that have formed to focus on thisarea (ie MMVR CyberTherapy The InternationalConference on Disability Virtual Reality and AssociatedTechnology The International Workshop on VirtualRehabilitation) the growth over the last five years inmembership on the VRPSYCH listserver (450 membersfrom 25 countries) and in the continued expansion inmultiuniversity VR collaborations

48 Integration of VR withPhysiological Monitoring andBrain Imaging

There is a rather compelling rationale for the inte-gration of VR with human physiological monitoringand brain imaging for advanced research in areas rele-vant to rehabilitation Research in such areas as psycho-physiology biokinesiology and neuropsychology havesimilar goals in that they aim to noninvasively recordbodily events or processes that are hypothesized to cor-relate with some human mental andor physical activityExamples of such efforts would include measuring gal-vanic skin responses (GSR) while a person attends toemotionally laden stimuli electromyographic recordingof muscle responses as a person reaches for a target andfunctional magnetic resonance imaging (fMRI) of hip-pocampal brain function while a person performs a way-finding task While these monitoring technologies haveexisted for some time the stimulus-delivery media hasremained essentially the same for many years relyingmainly on fixed audio and visual content The use of VRnow allows for measurement of human interaction withrealistic dynamic content albeit within the constraintsof the monitoring apparatus Thus far heart rate GSRand other psychophysiological measures have produceduseful results within VR studies examining attention andpresence (Pugnetti Mendozzi Barberi Rose amp Attree1996 Meehan Insko Whitton amp Brooks 2002) andhave been used to enhance treatment effects using a VRbiofeedback paradigm for fear-of-flying clients in Wied-erhold et al (2002) Even within the confines of a3-tesla magnetic-imaging device with the userrsquos head ina fixed position humans can navigate and interact in aVR world with specialized nonmetal displays and inter-

face devices In fact a significant body of research hasemerged using fMRI to study brain function in normaland clinical groups operating in virtual environments(Maguire et al 1998 Gron Wunderlich Spitzer Tom-szak amp Riepe 2000 Astur Mathalon DrsquoSouza Krys-tal amp Constable 2003 Baumann 2005) The strengthof VR for precise stimulus delivery within ecologicallyenhanced scenarios is well matched for this research andit is expected that continued growth will be seen in thisarea

49 Telerehabilitation

The concept of delivering rehabilitation and ther-apy to patients in remote locations for independent usehas been a popular topic since health care professionalsrecognized the growing reach and power of the Inter-net The application of VR within a telerehabilitationformat is the next logical opportunity for consideringways to improve access to this technology by a widergroup of potential beneficiaries VR applications that areInternet-deliverable could open up new possibilities forhome-based therapy and rehabilitation which if exe-cuted thoughtfully could increase client access enhanceoutcomes and reduce costs Future Internet distribu-tion of VR applications could also be supplemented bymaintaining connectivity between the remote client us-ing the system and a primary server at a rehabilitationfacility In this manner the clientrsquos home-based perfor-mance within the VR application could be trackedquantified analyzed and graphically represented in anintuitively understandable format for analysis by keyrehabilitation professionals charged with monitoringthis information In addition continual updating of theVR world and the actions and activities that it requiresof the client during rehabilitative exercises could be im-plemented both by the monitoring therapist and vialdquointelligentrdquo systems on the main server This function-ality would allow client progress to be efficientlytracked and this information could be used to evolvethe performance demands on the client in a manner de-signed to foster effective and efficient rehabilitative out-comes An example of some early efforts to apply VR ina telerehabilitation format for physical therapy are de-


tailed in other articles in this issue (Holden DyarSchwamm amp Bizzi 2005 Deutsch et al 2005) How-ever the possible benefits that could be accrued fromVR telerehabilitation applications are equally matchedby the enormous challenges that still need to be facedIt would be unfortunate for clinicians to become enam-ored with the obvious potential that exists with VR tele-rehabilitation yet lose sight of the sheer technical prac-tical clinical and ethical complexities that still need tobe addressed (Rizzo Strickland amp Bouchard 2004)

5 VR Rehabilitation Threats

51 Too Few CostBenefit Proofs CouldNegatively Impact Mainstream VRRehabilitation Adoption

While both intuition and early research findingssuggest that VR offers many strengths for rehabilitationpurposes the field lacks definitive costbenefit analysesSuch analyses must spell out both the clinical and eco-nomic benefits weighed against the costs for using VRover already-existing traditional methods (Rizzo Buck-walter amp van der Zaag 2002) This is a significant chal-lenge in view of the high initial development costs ofldquoone-off rdquo systems that have often characterized manyinspired VR applications thus far Without such costbenefit proofs health care administrators and main-stream practitioners who are concerned with the eco-nomic bottom line may have little motivation to spendmoney on high-tech solutions if there is no expectedfinancial gain This could result in a ldquoCatch-22rdquo sce-nario whereby limited investment is put into RampD thatintegrates enabling-technology advances into workingsystems that might produce favorable costbenefitproofs at a later time Favorable costbenefit proofs forVR use have been reported for military artillery-trainingapplications (Stone 2003) where tangible metrics arereadily available (ie criterion artillery performance as afunction of costs for real ammunition and equipment

maintenance etc vs VR hardwaresoftware costsetcover time) However for rehabilitation applica-tions in the age of modern health care the metrics areoften quite challenging for ldquoexperimentalrdquo treatments

While improving ldquoquality of liferdquo may be a lofty goal totarget for a patient following a stroke that type of suc-cessful outcome is typically of less interest to third-partypayers who are more focused on a ldquoreturn to workrdquometric Ironically problems may also arise when a VRtreatment shows too much value in attracting clients totherapy who would ordinarily avoid treatment This hasbeen observed in phobic clients who are willing to tryVR therapy after avoiding ldquostandardrdquo talk therapy formany years Health care payers are sometimes more in-terested in having fewer numbers of patients seek treat-ment if it negatively affects their bottom line (K Graappersonal communication January 11 2004) While thiscomplex topic is beyond the scope of this article a fineexample of a health care costbenefit analysis can befound in Holder (1998)

52 Aftereffects Lawsuit Potential

As discussed in the ldquoWeaknessesrdquo section afteref-fects may occur in users for various periods of time fol-lowing interaction in a VE The potential for such after-effects following VR usage opens the possibility that adeveloper clinician researcher or supporting institu-tion could be held liable for damages in the event thatsome injury should befall a patient upon leaving a VRsession One can easily imagine an unfortunate scenarioin which a patient has a car accident while driving homefrom a VR session and the potential legal difficulties thatmight ensue if a case were made that the accident wasdue to VR-induced perceptual aftereffects that impaireddepth perception Kennedy Kennedy amp Bartlett(2002) present an excellent detailing of these issues in achapter on VEs and product liability They suggest thatcertain human-factors safety actions be undertaken thatinclude ldquo1) Systems should be properly designed 2) After-effects should be removed guarded against or warnedagainst 3) Adaptation methods should be developed 4)Users should be certified to be at their pre-exposure levels5) Users should be monitored and debriefedrdquo (p 543)Until we have better data on these issues extra cautionmay be needed especially with clinical populationshaving some form of central-nervous-system dysfunc-tion where readaptation to the real world could cause

Rizzo and Kim 139

them to operate differently from unimpaired popula-tions For example in one of our recent VR studies test-ing visuospatial abilities with an elderly group (65years old) since we couldnrsquot be confident regarding theabsence of potential perceptual aftereffects we hadfunding built into our grant to provide transportationfrom the test site thereby minimizing any possible riskfor altered driving behavior resulting from the VR expo-sure Concerns such as these must be addressed in orderto ensure a positive course for developing VR applica-tions for all persons and particularly for clinical groups

53 Ethical Challenges

The feasibility of designing developing and im-plementing VR rehabilitation applications has radicallyadvanced in the last five years and it is expected that thisevolution will continue into the foreseeable futureAlong with any technological advance in the health caredomain come ethical questions that require thoughtfulconsideration As professionals directly involved in theapplication of this technology and as members of societyat large with a moral-ethical responsibility for the pro-motion and maintenance of health we are accountableto consider and address incumbent ethical threats thatsurround this emerging technology This is especiallyimportant in the rehabilitation sciences where researchand clinical applications with patient populations requirea rational accounting of the potential risks and benefitsAdditionally larger pragmatic and societal issues needto be addressed for VR applications with unimpairedusers regarding the general human experience and itsimpact on mental health As in any area of ethical de-bate clear-cut answers that cover all dilemmas are rarelyfound For example while immersion and interactivitymay enhance the realism of a VE these same featuresmay also create difficulties for certain individuals withpsychiatric conditions or cognitive impairments thatproduce distorted reality testing Specifically such con-ditions could result in increased vulnerability for nega-tive emotional responses during or following VR expo-sure Although such incidents have yet to be reported inthe VR literature insurance for monitoring responsesrelated to VR exposure becomes an ethical responsibility

for the professional While current therapeutic uses ofVR still require a clinician to be present future applica-tions may not have this requirement and this potentialldquoopportunityrdquo again underscores the need for advanceconsideration of the ethical issues pertinent to the use ofVR as a clinical tool As well as potent VR tools be-come more readily available for clinical purposes someclinicians may not have the qualifications or expertise todeliver services in the area that the tool was designed toaddress Such inappropriate administration of treatmentby a tech-savvy but unqualified health care providercould tarnish the credibility of the field in general andcreate a public image of VR rehabilitation professionalsas high-tech charlatans Since a full accounting of po-tential ethical threats in VR rehabilitation is beyond thescope (and page limits) of this article the reader is re-ferred to Rizzo Schultheis et al (2002) for a detailedreview of the use of VR in clinical practice and its po-tential societal impact

54 The Perception That VR Tools WillEliminate the Need for the Clinician

Discussion of the use of VR as a therapeutic toolcan sometimes raise concerns regarding the status of theclinician when applying technology for therapeutic pur-poses One issue cited as a barrier for implementation ofcomputerized therapies is the potential impact on thesanctity of patient-therapist relationship (Gould 1996)Ironically a strong form of this argument can be seen inwriting on the use of computerized therapy by MIT AIresearcher Joe Weizenbaum who wrote a language-analysis program called ELIZA that was initially de-signed to imitate a Rogerian psychotherapist Weizen-baum (1976) concluded that it would be immoral tosubstitute a computer for a human function that ldquoin-volves interpersonal respect understanding and loverdquo(cf Howell amp Muller 2000) While admittedly hisview emerged out of the ldquoshockrdquo he experienced uponlearning how seriously people took the ELIZA pro-gram even basic automated computer applications inldquodrill and practicerdquo cognitive remediation were metwith criticism from some professionals who argued thatthe introduction of computers was equivalent to the


removal of the therapist (cf Robertson 1990) Al-though supporters of VR therapy and rehabilitation arequick to point out that these applications are simplytools that extend the therapistrsquos expertise there still ex-ists a view in some clinical quarters that any technologyserves to subvert the clinical relationship The impact ofthis threat will likely increase as more-believable humanagents begin to populate VR applications

The issue of therapist acceptance will likely be sur-mounted in time if VR applications continue to demon-strate benign added value but similar impressions onthe part of potential patients also need to be consideredFor example will greater access to VR applications viathe Internet encourage individuals to undertake self-treatment without feeling the need for professionalguidance Or will slick marketing of costly VR rehabili-tation programs that lack evidence for effectiveness en-tice both desperate family members and naıve clients toself-diagnose and self-administer treatment yet deliverno tangible benefit These practical clinical issues needto be considered in advance of widespread availabilityand adoption of VR rehabilitation applications

55 Limited AwarenessUnrealisticExpectations

This threat is a counterpoint to the ldquoopportunityrdquocited above regarding widespread intuitive appeal of VRto the general public All first-time VR users bring intothe situation a set of expectations Oftentimes theseexpectations are based on overhyped media representa-tions of what VR can deliver If someonersquos expectationis the Holodeck it is likely that they will be disap-pointed when they are required to don an array of en-cumbering devices that support primitive interaction inan imperfect replica of the real world Perhaps the bestremedy for this (aside from continuing to innovate) is inthe conduct of research that tests (and hopefully sup-ports) the validity and added value of a given VR appli-cation along with the honest acceptance that we still infact have a long way to go Our labrsquos rule of thumb forVR demos is to usually spend some time preexposure tobrief the person on the rationale for a VR applicationdiscuss some of the methods that we have been previ-

ously limited to with traditional non-VR tools and haveposters in the lab from previous conferences that presentefficacy data from the application being demonstrated

On the other hand modulating expectations thatcontinue to be unrealistic in those who are familiar withVR can serve another purpose Mainstream researchersand clinicians are beginning to take notice of thisemerging technology and it is important that it is notviewed as a panacea for all rehabilitation concerns Thehistory of medicine provides numerous examples of theoverexploitation of new technologies based on over-wrought expectations and little data The medical use ofelectricity serves as an example of a commonly acceptedprocedure in the nineteenth century during which timefaulty expectations combined with an urgency to imple-ment a potential ldquomiraclerdquo cure resulted in many clini-cians with minimal to no experience in the physics ofelectricity misapplying the technique to patients (Whal-ley 1995) Similarly with todayrsquos growing interest inthe use of VR for clinical research and treatment it isessential that hype does not displace reason in both thepresentation and use of the technology

6 Conclusions

The view that emerges (to us) from this SWOTanalysis suggests that the field of VR rehabilitation isstill in an early phase of development characterized bysuccessful ldquoproof of conceptrdquo systems encouraging ini-tial research results and a few applications that are find-ing their way into mainstream use and clinical practiceMany VR strengths are specified that will continue toprovide a justification for evolving existing applicationsand creating new ones Weaknesses exist particularlywith certain limitations in areas of interface and displaytechnology but do not threaten the viability of the fieldin light of recent and expected opportunities in theform of advances in the underlying VR-enabling tech-nologies With thoughtful system design that targetsclinical and research applications that are well matchedto current technology assets and limitations it is pre-dicted that VR rehabilitation will continue to graduallygrow and gain acceptance as a mainstream tool Threats

Rizzo and Kim 141

to the field do exist but none are ldquofatalrdquo and all arelikely addressable with the high motivation andthoughtfulness that seems to exist with the many re-searchers clinicians and general proponents of thisfield From this analysis our general prescription foradvancing VR rehabilitation can be summed up suc-cinctly Applications need to be developed with strongmultidisciplinary collaboration and with continuoususer-centered inputevaluation methods This is neededto ensure the soundness of the rationale for the applica-tion and to create something that is usable within thecurrent limits of technology Researchers need to ini-tially collect incremental data over numerous small-scaleparametric studies to test and evolve usability useful-ness and access especially with targeted user groupsDuring this time in advance of deployment of a systemethical professional and costbenefit issues need to beconsidered and specified And along the way share yourapplications with other interested researchers to see ifthey can independently operate your system and repli-cate your results While the field is not without its chal-lenges as the technology continues to catch up with thevision it is our view that VR will have a significant posi-tive impact on the rehabilitation sciences

References

Allison M Okamura J Dennerlein T amp Howe R D(1998) Vibration feedback models for virtual environ-ments IEEE International Conference on Robotics and Au-tomation 1 674ndash679

Astur R S Mathalon D H DrsquoSouza D C Krystal J Hamp Constable R T (2003) fMRI assessment of hippocam-pus function in participants with schizophrenia using a vir-tual morris water task Cognitive Neuroscience Society Ab-stracts

Baek S Lee S amp Kim G J (2003) Motion retargettingand evaluation for VR based motion training of free mo-tions Visual Computer 19(6)

Barrett J McCrindle R J Cook G K amp Booy D A(2002) Accessible interface design A review of access to infor-mation and communication technology for older and disabledpeople (Tech Rep) Reading UK University of ReadingDepartment of Computer Science

Baumann S (2005) A neuroimaging study of task loadingand executive function using a virtual apartment PresenceTeleoperators and Virtual Environments 14(2) 183ndash190

Biederman I (2002 May) A neurocomputational hypothesisof perceptual and cognitive pleasure Invited paper pre-sented at the Ninth Joint Symposium on Neural Computa-tion California Institute of Technology Pasadena Availablefrom httpwwwitscaltechedujsncprogramhtml

Bowman D Kruijff E LaViola J J amp Poupyrev I(2001) An introduction to 3-D user interface design Pres-ence Teleoperators and Virtual Environments 10 96ndash108

Broeren J Bjorkdahl A Pascher R amp Rydmark M(2002) Virtual reality and haptics as an assessment device inthe post acute phase after stroke CyberPsychology amp Behav-ior 5(3) 207ndash211

Brooks B M McNeil J E Rose F D Greenwood R JAttree E A amp Leadbetter A G (1999) Route learningin a case of amnesia A preliminary investigation into theefficacy of training in a virtual environment Neuropsycholog-ical Rehabilitation 9 63ndash76

Brown D J Kerr S J amp Bayon V (1998) The develop-ment of the virtual city A user centred approach In PSharkey D Rose amp J Lindstrom (Eds) Proceedings of theSecond European Conference on Disability Virtual Realityand Associated Technologies (ECDVRAT) (pp 11ndash16)Reading UK University of Reading

Burdea G C (1996) Force and touch feedback for virtualreality New York Wiley

Burdea G Popescu V Hentz V amp Colbert K (2000)Virtual reality-based orthopedic tele-rehabilitation IEEETransaction on Rehabilitation Engineering 8(3) 429ndash432

Canesta (2004) Available from wwwcanestacomindexhtm

Christiansen C Abreu B Ottenbacher K Huffman KMassel B amp Culpepper R (1998) Task performance invirtual environments used for cognitive rehabilitation aftertraumatic brain injury Archives of Physical Medicine andRehabilitation 79 888ndash892

Cohen I Li H amp Lee M W (2002 December) Humanbody posture inference for immersive interaction ACMMultimedia 2002 Juan Les Pins France

Collett S (1999 July 19) SWOT analysis ComputerworldAvailable from httpwwwcomputerworldcomnews1999story0112804296800html

Connor B Wing A M Humphreys G W BracewellR M amp Harvey D A (2002) Errorless learning usinghaptic guidance Research in cognitive rehabilitation follow-


ing stroke In P Sharkey C S Lanyi amp P Standen (Eds)Proceedings of the Fourth International Conference on Dis-ability Virtual Reality and Associated Technology (ICD-VRAT) (pp 77ndash86) Reading UK University of Reading

Costas R Carvalho L amp de Aragon D (2000) Virtual cityfor cognitive rehabilitation In P Sharkey A Cesarani LPugnetti amp A Rizzo (Eds) Proceedings of the Third ICD-VRAT (pp 305ndash313) Reading UK University of Read-ing

Cromby J Standen P Newman J amp Tasker H (1996)Successful transfer to the real world of skills practiced in avirtual environment by students with severe learning disabil-ities In P M Sharkey (Ed) Proceedings of the First ECD-VRAT (pp 305ndash313) Reading UK University of Read-ing 103ndash107

Cybergrasp (2004) Available from httpwwwimmersioncom3dproductscyber_graspphp

Davies R C Lofgren E Wallergard M Linden A Bos-chian K Minor U et al (2002) Three applications ofvirtual reality for brain injury rehabilitation of daily tasks Apractical example using virtual reality in the assessment ofbrain injury In P Sharkey C S Lanyi amp P Standen(Eds) Proceedings of the Fourth ICDVRAT (93ndash100)Reading UK University of Reading

Davis E S amp Wachtel J (2000 January) Interactive driv-ing simulation as a tool for insight development and motiva-tion in a rehabilitation setting Paper presented at the EighthAnnual Medicine Meets Virtual Reality Conference New-port Beach CA

Deutsch J E Latonio J Burdea G amp Boian R (2001)Post-stroke rehabilitation with the Rutgers ankle system acase study Presence Teleoperators and Virtual Environ-ments 10 416ndash430

Deutsch J E Lewis J A Whitworth E Boian R BurdeaG amp Tremaine M (2005) Formative evaluation and pre-liminary findings of a virtual-reality telerehabilitation systemfor the lower extremity Presence Teleoperators and VirtualEnvironments 14(2) 198ndash213

Digiplay Initiative (2002) Available from httpwwwdigiplayorgukindex2php

DiZio P amp Lackner J R (1992) Spatial orientation adap-tation and motion sickness in real and virtual environmentsPresence Teleoperators and Virtual Environments 1 323

DMW (2004) Available from httpwwwdmwcaindex_framehtml

Duda R O (2004) 3-D audio for HCI Available from

www-engrsjsueduknappHCIROD3D3D_homehtm

Elkind J S Rubin E Rosenthal S Skoff B amp Prather P(2001) A simulated reality scenario compared with thecomputerized Wisconsin Card Sorting test An analysis ofpreliminary results Cyberpsychology and Behavior 4 489ndash496

EyeToy (2004) Available from wwweyetoycomFernando R amp Kilgard M (2003) The CG Tutorial The

definitive guide to programmable real time graphics BostonAddison Wesley

Glantz K Rizzo A A amp Graap K (2003) Virtual realityfor psychotherapy Current reality and future possibilitiesPsychotherapy Theory Research Practice Training 40(12)55ndash67

Gould R L (1996) The use of computers in therapy In TTrabin (Ed) The computerization of behavioral healthcare(pp 39ndash62) San Francisco Jossey-Bass

Greenhill L L (1998) Diagnosing attention-deficithyper-activity disorder in children Journal of Clinical Psychiatry59(Suppl 7) 31ndash41

Gron G Wunderlich A P Spitzer M Tomszak R ampRiepe M W (2000) Nature Neuroscience 3(4) 404ndash408

Harrison A Derwent G Enticknap A Rose F D amp At-tree E A (2002) The role of virtual reality technology inthe assessment and training of inexperienced poweredwheelchair users Disability and Rehabilitation 24 599ndash606

Hettinger L J (1992) Visually induced motion sickness invirtual environments Presence Teleoperators and VirtualEnvironments 1 306ndash307

Hirota K amp Hirose M (1995) Surface display Concept andimplementation approaches Proceedings of the Fifth Interna-tional Conference on Artificial Reality and Tele-Existence(185ndash192)

Holden M K Dyar T A Schwamm L amp Bizzi E(2005) Virtual-environment-based telehabilitation in pa-tients with stroke Presence Teleoperators and Virtual Envi-ronments 14(2) 214ndash233

Holder H D (1998) Cost benefits of substance abuse treat-ment An overview of results from alcohol and drug abuseThe Journal of Mental Health Policy and Economics 1 23ndash29

Howell S R amp Muller R (2000) Available from httpwwwpsychologymcmastercabeckerlabshowellComputerTherapyPDF

Rizzo and Kim 143

ICT (2004) Available from httpwwwictuscedudispphpbdproj_games

Ikei Y amp Stiratori M (2002) TextureExplorer A tactileand force display for virtual textures Proceedings of theTenth IEEE Symposium On Haptic Interfaces For VirtualEnvironment amp Teleoperator Systems (HAPTICS02)0-7695-1489-802

Jack D Boian R Merians A Tremaine M Burdea GAdamovich S et al (2001) Virtual reality-enhanced strokerehabilitation IEEE Transactions on Neurological Systemsand Rehabilitation Engineering 9 308ndash318

Jaffe D L (1998) Use of virtual reality techniques to trainelderly people to step over obstacles Paper presented at theTechnology and Persons with Disabilities Conference LosAngeles CA

Jang Y Yang U amp Kim G J (2002) Designing a vibro-tactile wear for close range interaction for VR based motiontraining International Conference on Artificial Reality andTelexistence 4ndash9

Kennedy R S Berbaum K S amp Drexler J (1994) Meth-odological and measurement issues for identification of en-gineering features contributing to virtual reality sicknessPaper presented at Image 7 Conference Tucson AZ

Kennedy R S Kennedy K E amp Bartlett K M (2002)Virtual environments and product liability In K Stanney(Ed) Handbook of virtual environments (pp 534ndash554)New York Erlbaum

Kennedy R S amp Stanney K M (1996) Postural instabilityinduced by virtual reality exposure Development of certifi-cation protocol International Journal of Human-ComputerInteraction 8(1) 25ndash47

Kizony R Katz N amp Weiss P (2003) Adapting an im-mersive virtual reality system for rehabilitation The Journalof Visualization and Computer Animation 14 1ndash7

Kolasinski G (1995) Simulator sickness in virtual environ-ments (Tech Rep 1027) Orlando FL United States ArmyResearch Institute for the Behavioral and Social Sciences

Lahav O amp Mioduser D (2002) Multi-sensory virtual en-vironment for supporting blind personsrsquo acquisition of spa-tial cognitive mapping orientation and mobility skills In PSharkey C S Lanyi amp P Standen (Eds) Proceedings of theFourth ICDVRAT (pp 213ndash222) Reading UK Universityof Reading

Laird J (2001) Using a computer game to develop advancedAI Computer 34(7) 70ndash75

Liu L Miyazaki M amp Watson B (1999) Norms and va-lidity of the DriVR A virtual reality driving assessment for

persons with head injuries Cyberpsychology amp Behavior 253ndash67

Lowenstein D (2002) Essential facts about the video andcomputer game industry Available from httpwwwidsacompressroomhtml

Lumbreras M amp Sanchez J (2000) Usability and cognitiveimpact of the interaction with 3D virtual interactive acousticenvironments by blind children In P Sharkey A CesaraniL Pugnetti amp A Rizzo (Eds) Proceedings of the ThirdICDVRAT (129ndash136) Reading UK University of Read-ing

MacFarlane M Rosen J Hannaford B Pellegrini C ampSinanan M (1999) Force feedback grasper helps restorethe sense of touch in minimally invasive surgery Journal ofGastrointestinal Surgery 3 278ndash285

Maguire E A Burgess N Donnett J G FrackowiakR S J Frith C D amp OrsquoKeefe J (1998) Knowingwhere and getting there A human navigation network Sci-ence 280 921ndash924

Massie T H Salisbury J K (1994) The PHANTOM hap-tic interface A device for probing virtual objects In C JRadcliffe (Ed) ASME Dynamic Systems and Control (1)295ndash301

McComas J MacKay M amp Pivak J (2002) Effectivenessof virtual reality for teaching pedestrian safety CyberPsychol-ogy and Behavior 5 185ndash190

McGeorge P Phillips L H Crawford J R Garden S EDella Sala S Milne A B et al (2001) Using virtual en-vironments in the assessment of executive dysfunction Pres-ence Teleoperators and Virtual Environments 10 375ndash383

Meehan M Insko B Whitton M amp Brooks F P (2002)Physiological measures of presence in stressful virtual envi-ronments Proceedings of SIGGRAPH 2002 San AntonioTX

Moncur M amp Moncur L (2002) QuotationsPagecomAvailable from httpwwwquotationspagecomquotesPlato

Mowafty L amp Pollack J (1995) Train to travel Ability 1518ndash20

Naveh Y Katz N amp Weiss P (2000) The effect of interac-tive virtual environment training on independent safe streetcrossing of right CVA patients with unilateral spatial ne-glect In P Sharkey A Cesarani L Pugnetti amp A Rizzo(Eds) Proceedings of the Third ICDVRAT (243ndash248)Reading UK University of Reading

Neisser U (1978) Memory What are the important ques-tions In M M Gruneberg P E Morris amp R N Sykes


(Eds) Practical aspects of memory (pp 3ndash24) London Ac-ademic Press

Norcross J C Hedges M amp Prochaska J O (2002) Theface of 2010 A Delphi poll on the future of psychotherapyProfessional Psychology Research and Practice 33 316ndash322

Preece J Rogers Y amp Sharp H (2002) Interaction design(1st ed) Hoboken NJ Wiley

Prensky M (2001) Digital Game-Based Learning NewYork McGraw-Hill

Psotka J (1995) Immersive training systems Virtual realityand education and training Instructional Science 23 405ndash431

Pugnetti L Mendozzi L Attree E Barbieri E BrooksB M Cazzullo C L et al (1998) Probing memory andexecutive functions with virtual reality Past and presentstudies CyberPsychology and Behavior 1 151ndash162

Pugnetti L Mendozzi L Barberi E Rose F D amp At-tree E A (1996) Nervous system correlates of virtual real-ity experience In P Sharkey (Ed) Proceedings of the FirstEuropean Conference on Disability Virtual Reality and Asso-ciated Technology (239ndash246) Maidenhead UK Universityof Reading

Reason J T (1970) Motion sickness A special case of sen-sory rearrangement Advancement in Science 26 386ndash393

Regan E amp Price K R (1994) The frequency of occur-rence and severity of side-effects of immersion virtual realityAviation Space amp Environmental Medicine 65 527ndash530

Riva G (2002) Virtual reality for health care The status ofresearch Cyberpsychology amp Behavior 5(3) 219ndash225

Rizzo A A Bowerly T Buckwalter J G SchultheisM T Matheis R Shahabi C et al (2002) Virtual envi-ronments for the assessment of attention and memory pro-cesses The virtual classroom and office In P Sharkey C SLanyi amp P Standen (Eds) Proceedings of the FourthICDVRAT (3ndash12) Reading UK University of Reading

Rizzo A A Buckwalter J G amp van der Zaag C (2002)Virtual environment applications for neuropsychologicalassessment and rehabilitation In K Stanney (Ed) Hand-book of virtual environments (pp 1027ndash1064) New YorkErlbaum

Rizzo M Reinach S McGehee D amp Dawson J (1997)Simulated car crashes and crash predictors in drivers withAlzheimerrsquos disease Archives of Neurology 54 545ndash551

Rizzo A A Schultheis M T Kerns K amp Mateer C(2004) Analysis of assets for virtual reality applications inneuropsychology Neuropsychological Rehabilitation 14(1)207ndash239

Rizzo A A Schultheis M T amp Rothbaum B (2002)Ethical issues for the use of virtual reality in the psychologi-cal sciences In S Bush amp M Drexler (Eds) Ethical issuesin clinical neuropsychology (pp 243ndash280) Lisse NL Swetsamp Zeitlinger

Rizzo A A Strickland D amp Bouchard S (2004) Issuesand challenges for using virtual environments in telereha-bilitation Telemedicine Journal and e-Health

Robertson I (1990) Does computerized cognitive rehabilita-tion work A review Aphasiology 4 381ndash405

Robillard G Bouchard S Fournier T amp Renaud P(2003) Anxiety and presence during VR immersion Acomparative study of the reactions of phobic and non-phobic participants in therapeutic virtual environments de-rived from computer games Cyberpsychology amp Behavior6(5) 467ndash476

Rolland J P Biocca F A Barlow T amp Kancherla A(1995) Quantification of adaptation to virtual-eye locationin see-thru head-mounted displays Proceedings of the IEEEVirtual Reality Annual International Symposium rsquo95 (pp55ndash66) Los Alamitos CA IEEE Computer Society Press

Rose D Brooks B M amp Attree E A (2000) Virtual real-ity in vocational training of people with learning disabilitiesIn P Sharkey A Cesarani L Pugnetti amp A Rizzo (Eds)Proceedings of the Third ICDVRAT (129ndash136) ReadingUK University of Reading

Rose F D Attree E A Brooks B M amp Andrews T K(2001) Learning and memory in virtual environmentsmdashArole in neurorehabilitation Questions (and occasional an-swers) from UEL Presence Teleoperators and Virtual Envi-ronments 10 345ndash358

Sadowski W amp Stanney K (2002) Presence in virtual envi-ronments In K Stanney (Ed) Handbook of virtual envi-ronments (pp 791ndash806) New York Erlbaum

Schultheis M T amp Mourant R R (2001) Virtual realityand driving The road to better assessment of cognitivelyimpaired populations Presence Teleoperators and VirtualEnvironments 10 436ndash444

Schultheis M T amp Rizzo A A (2002 January) The virtualoffice Assessing amp re-training vocationally relevant cogni-tive skills Paper presented at the Tenth Annual MedicineMeets Virtual Reality Conference Newport Beach CA

Sense8 (2004) Available from wwwsense8comSeo J amp Kim G J (2002) Design for presence A struc-

tured approach to VR system design Presence Teleoperatorsand Virtual Environments 11(4) 378ndash403

Rizzo and Kim 145

SGI Homepage (2004a) Available from wwwsgicomSGI Homepage (2004b) Available from wwwsgicom

productsevaluationwindows_performer_302Sims (2004) Available from wwweagamescomhomejspSohlberg M M amp Mateer C A (2001) Cognitive rehabili-

tation An integrative neuropsychological approach NewYork Guilford

Stanney K M Salvendy G et al (1998) Aftereffects andsense of presence in virtual environments Formulation of aresearch and development agenda Report sponsored by theLife Sciences Division at NASA Headquarters InternationalJournal of Human-Computer Interaction 10(2) 135ndash187

Stanton D Foreman N amp Wilson P (1998) Uses of vir-tual reality in clinical training Developing the spatial skillsof children with mobility impairments In G Riva B Wied-erhold amp E Molinari (Eds) Virtual reality in clinical psy-chology and neuroscience (pp 219ndash232) Amsterdam IOS

Stone R J (2003 May) Whatever happened to virtual real-ity The Laval International Virtual Reality ConventionLaval France Available from httpwwwets-newscomvirtual03htm

Strickland D (2001 August) Virtual reality and multimediaapplications for mental health assessment and treatmentPaper presented at the ACM SIGGRAPH 2001 Conference

Tan H Z amp Pentland A (1997 October) Tactual displayfor wearable computing Proceedings of the InternationalSymposium on Wearable Computing (pp 84ndash89) Cam-bridge MA

Wann J P amp Mon-Williams M (1996) What does virtualreality need Human factors issues in the design of threedimensional computer environments International Journalof Human-Computer Studies 44 829ndash847

Weiser M amp Brown A (1996) Designing calm technology

PowerGrid Journal available at httppowergridelectriciticom101

Weiss P amp Jessel A S (1998) Virtual reality applications towork Work 11 277ndash293

Weizenbaum J (1976) Computer power and human reasonSan Francisco W H Freeman

Whalley L J (1995) Ethical issues in the application of vir-tual reality to medicine Computer Biology and Medicine25(2) 107ndash114

Wiederhold B K Jang D P Gevirtz R G Kim S IKim I Y amp Wiederhold M D (2002) The treatmentof fear of flying A controlled study of imaginal and vir-tual reality graded exposure therapy IEEE Transactionson Information Technology in Biomedicine 6(3) 218ndash222

Wiederhold B K amp Wiederhold M D (1998) A review ofvirtual reality as a psychotherapeutic tool CyberPsychology ampBehavior 1(1) 45ndash52

Wilson B A amp Evans J J (1996) Error-free learning in therehabilitation of people with memory impairments Journalof Head Trauma Rehabilitation 11 54ndash64

Wren C Azarbayejani A Darrell T and Pentland A(1997) Pfinder Real-time tracking of the human bodyIEEE Transactions on Pattern Analysis and Machine Intelli-gence 19(7) 780ndash 785

Xbox (2004) Available at httpwwwgames-chart comxboxinfohtml

Yang U amp Kim G J (2002) Just follow me An immersiveVR-based motion training system Presence Teleoperatorsand Virtual Environments 11(3) 304ndash323

Zimand E Anderson P Gershon G Graap K HodgesL amp Rothbaum B (2003) Virtual reality therapy Innova-tive treatment for anxiety disorders Primary Psychiatry9(7) 51ndash54


relevant ecologically enhanced VEs a fundamental ad-vancement could emerge in how human functioningcan be addressed in many rehabilitation disciplines

But we know that already What we donrsquot know isWhat place will VR occupy in the future of rehabilitation

Depending on who you ask yoursquore likely to hear avariety of responses to that question that might includesuch words as ldquoVisionaryrdquo ldquotoo expensiverdquo ldquojust whatthe field needsrdquo ldquobut how will that impact the thera-pistrsquos rolerdquo ldquosounds like the Holodeckrdquo ldquoneed betterinterfacesrdquo ldquohmm interesting possibilitiesrdquo ldquocanthey really do thatrdquo and so forth In essence the viewthat one takes of VR and its potential to add valueover existing rehabilitation tools and methods is ofteninfluenced by such factors as onersquos faith in technol-ogy economic concerns frustration with the existinglimitations of traditional tools fear of technologypopular-media influences pragmatic awareness ofcurrent hardware limitations curiosity and healthyskepticism

For those working in the ldquotrenchesrdquo trying to employVR in a meaningful way for rehabilitation purposes (or forthose just getting their feet wet) a more systematic strat-egy for evaluating the state of the field could be of valuefor informing onersquos judgment decision making andguesses as to whatrsquos possible now and what lies ahead inthe future Without applying a structured framework to aidonersquos thinking about the current status and future of VRand rehabilitation it is quite easy to regularly oscillate be-tween flights of wishful thinking and bouts of abject dis-couragement depending on the daily ebb and flow of pro-vocative data and system crashes Perhaps our susceptibilityto this sort of bipolar ldquosecond-guessingrdquo of VR could bereduced if one is armed with a comprehensive yet intuitivemethod for organizing the myriad factors that will serveboth to enable and to limit how well we can successfullytranslate our virtual-reality rehabilitation vision into actualreality Such a strategy may also help us to identify realisticgoals and establish priorities regarding which clients arethe most appropriate candidates for VR and which tech-nologies are best suited to creating applications to meettheir needs Although a high capacity to live with ambigu-ity is a requirement for those who explore novel emergingapproaches in any discipline a focused approach for guid-

ing our expectations could make that process more man-ageable and productive in the long run

In view of these issues this paper will present aSWOT analysis for the field of VR and the rehabilitationsciences (see Figure 1) SWOT is actually an acronymthat stands for strengths weaknesses opportunities andthreats and is a commonly employed framework in thebusiness world for analyzing the factors that influence acompanyrsquos competitive position in the marketplace withan eye to the future A classic success story for the valueof a SWOT analysis is Dell Computer Corporationrsquos useof the framework to make the strategic decision to im-plement mass customization just-in-time manufactur-ing and direct Internet sales (Collett 1999) Howeverthe SWOT framework can also be usefully applied out-side of the pure business domain A quick check on theInternet will turn up SWOT analyses for urban-renewalprojects career planning website design youth sportsprograms evaluation of academic research centers andit becomes obvious that it can be usefully applied toguide any organized human endeavor designed to ac-complish a mission

Generally a SWOT analysis serves to uncover the op-timal match between the internal strengths and weak-nesses of a given entity and the environmental trends(opportunities and threats) that the entity must face inthe marketplace

A strength can be viewed as a resource a uniqueapproach or capacity that allows an entity toachieve its defined goals (eg VR can allow for pre-cise control of stimulus delivery within a realistictraining or rehabilitation simulation)

A weakness is a limitation fault or defect in theentity that impedes progress toward defined goals(eg the limited field of view and resolution in ahead-mounted display can limit usability and per-ceptual realism)

An opportunity pertains to internal or externalforces in the entityrsquos operating environment suchas a trend that increases demand for what the entitycan provide or allows the entity to provide it moreeffectively (eg tremendous growth in the interac-tive digital gaming area has driven development of











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6 Conclusions


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6 Conclusions


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6 Conclusions


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6 Conclusions


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6 Conclusions


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6 Conclusions


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6 Conclusions


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6 Conclusions


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albert skip rizzo a swot analysis of the field of ... · the use of virtual-reality technology in...

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