BASIC ISSUES IN THE USE OF VIRTUAL ENVIRONMENTS FOR MENTAL HEALTH APPLICATIONS

GIUSEPPE RIVA, BRENDA K. WIEDERHOLD, ENRICO MOLINARI (Eds.)Virtual Environments in Clinical Psychology and Neuroscience1998 © Ios Press: Amsterdam, Netherlands.

BASIC ISSUES IN THE USE OFVIRTUAL ENVIRONMENTS FOR

MENTAL HEALTH APPLICATIONS1 ALBERT A. RIZZO, 2 MARK WIEDERHOLD, 1 J. GALEN BUCKWALTER

1 Andrus Gerontology CenterUniversity of Southern California, Los Angeles, CA, USA

2 Scripps ClinicLa Jolla, CA, USA

Abstract. In order for Virtual Environments (VE) to be efficiently developed in the areasof clinical psychology and neuropsychology, a number of basic theoretical and pragmaticissues need to be considered. The current status of VEÕs in these fields, while provocative,is limited by the small number of controlled studies that have been reported which applythis technology to clinical populations. This is to be expected considering itÕs relativelyrecent development, expense, and the lack of familiarity with the technology bymainstream researchers in these fields. In spite of this, some work has emerged which canbegin to provide a basic foundation of knowledge which could be useful for guiding futureresearch efforts. Although much of the work does not involve the use of fully immersivehead mounted displays (HMDÕs), studies reporting PC-based flatscreen approaches areproviding valuable information on issues necessary for the reasonable and measureddevelopment of VE/mental health applications. In light of this, the following review willfocus on basic issues that we see as important for the development of both HMD and non-HMD VE applications for clinical psychology, neuropsychological assessment, andcognitive rehabilitation. These basic issues are discussed in terms of decision-making forchoosing to develop and apply a VE for a mental health application. The chapter coversthe issues involved with choosing a VE approach over already existing methods, decidingon the ÒfitÓ between a VE approach and the clinical population, level of presence,navigation factors, side effects, generalization, and general methodological and dataanalysis concerns.

1 . Introduction

After an early period of inflated expectations and limited delivery, Virtual RealityTechnology is now beginning to emerge as a viable tool for mental health applications. Virtualenvironments (VE) have been developed which are now demonstrating effectiveness in theareas of clinical psychology and neuropsychology. These applications have shown promisefor addressing: fear reduction with phobic clients [1,2,3,4,5,6,7], pain reduction for burnpatients [8], stress reduction in cancer patients [9], eating disorders/body image disturbances[10] , navigation and spatial training in children with motor impairments [11,12], functionalskills in persons with developmental disabilities and autism [13,14,15], and in the assessment(and in some cases, rehabilitation) of memory [16], attention [17], spatial skills[18,19], andexecutive cognitive functions [20]. These efforts are no small feat in light of the technologicalchallenges and funding hurdles that many of these researchers have faced in the developmentof this emerging technology. Also, the therapeutic targets chosen for these applications reflectan informed appreciation for the unique assets that are available using virtual technology.

However, in order for VEÕs to be efficiently developed in the areas of clinical psychologyand neuropsychology, a number of basic theoretical and pragmatic issues need to beconsidered. The current status of VEÕs in these fields, while provocative, is limited by thesmall number of controlled studies that have been reported which apply this technology to


clinical populations. This is to be expected considering the technologyÕs recent development,itÕs relatively high initial development costs, and the lack of familiarity with VEÕs byestablished researchers using traditional tools and tactics in these fields. In spite of this, somework has emerged which can begin to provide a basic foundation of knowledge which couldbe useful for guiding future research efforts. Although much of the work does not involve theuse of fully immersive headmounted displays (HMDÕs), studies reporting 3D projectionscreen, and PC-based flatscreen approaches are providing valuable information on issuesnecessary for the reasonable and measured development of VE/mental health applications. Inlight of this, the following review will focus on the basic cost/benefit issues (Table 1) that wesee as important for the development of both HMD and non-HMD VE applications for clinicalpsychology, neuropsychological assessment, and cognitive rehabilitation. For clarity sake,the term Òmental health (MH) applicationsÓ will be used in this chapter to generally denoteboth clinical psychology and neuropsychology applications, unless specificity requires the useof the individual terms. Also it is assumed that the reader is familiar with the basic definitions,equipment, and concepts pertaining to virtual reality and virtual environments. For thoseunfamiliar with these topics a number of useful books and articles are available [21,25].

Table 1. Basic VE Cost/Benefit Issues for Mental Health Applications1) Can the same objective be accomplished using a simpler approach?2) How well do the current attributes of a VE fit the needs of the psychological approach

or target?3) How does a VE approach match the characteristics of the target clinical population?4) What is the optimal level of presence necessary for the application?5) Will the target users be able to learn to navigate in and interact with the environment in

an effective manner?6) What is the potential for side-effects (cybersickness and aftereffects) in light of the

characteristics of different clinical groups?7) Will assessment results and treatment effects generalize to the Òreal worldÓ?8) How should VE studies be designed and how will the data be analyzed?

2 . Can the same objective be accomplished using a simpler approach?

While VE technology appears to offer many advantages for MH applications, the first stepfor any such program is for the developer to perform a realistic cost/benefit analysis.Awareness of the importance of an honest cost/benefit analysis can serve to prevent costly andmisguided (though well-intentioned) system development from diverting resources from theareas where a VE approach can make a unique and useful contribution. Virtual reality hasbeen characterized as a technology in search of an application [26]. From this, the excitementwhich has surrounded this new technology has the potential to affect judgment of the realneeds of the situation. The first question that needs to be asked is: Does the objective that isbeing pursued require the expense and complexity of a VE approach, or can it be done aseffectively and efficiently using simpler, less costly, and currently available means? Thiscould be termed the Òelegant simplicityÓ criterion and requires the investigator to fullyconsider the objectives of the application, and decide whether the development of a VEgenuinely adds value beyond what already exists, or is it simply a case of technologicaloverkill!

VEÕs in fact, offer immersive and interactive features that, if deemed important to a MHapproach, could provide valuable assets. However, if these features are not of vitalimportance, perhaps the use of multimedia, ÒsimpleÓ video, or even already established invivo tools, would be sufficient. For example, relaxation training for generalized stressreduction may be enhanced by designing pleasant VEÕs for a person to experience. But wouldthis really add value to treatments of already demonstrated efficacy which utilize deepbreathing, progressive muscle relaxation, and imaginal methods that can be applied in thepersonÕs unique and specific in vivo target environments? Conversely, certain high stressenvironments are chronically avoided (both physically and imaginally) by personÕs with


specific phobia and anxiety disorders. The design and use of a VE modeled after these fearedenvironments may offer the only opportunity for an exposure-based reduction of fear oranxiety with these clients. Hence, the useful and value-added VE approaches that targetspecific fears of flying, heights, public speaking, etc. have been some of the first systems todemonstrate positive results.

This same logic applies for neuropsychological assessment applications. For example, ifyour objective is to assess elderly persons for global cognitive functioning as an initialscreening procedure for dementia (AlzheimerÕs, Vascular, ParkinsonÕs, etc.), then a verybasic, standardized 30 question mental status interview/exam that measures orientation,attention, short and long term memory, verbal fluency, and judgment may be sufficient forthis purpose. A test like this already exists, the Mini Mental State Exam, and has been shownto be of acceptable reliability and validity, inexpensive, easy to administer quickly in mostsettings, and provides data that can be usefully compared with norms generated over manyyears as a standard tool in this area [27]. For this specific purpose, a VE approach would beredundant and inefficient. However, the same researcher may believe that probableAlzheimerÕs disease could be recognized at itÕs very earliest stages via a more systematicanalysis of specific attention/memory components (perhaps iconic memory) while the client isimmersed within the demands of a stimulus-rich functional VE. In this case, for this purpose,a VE application may be the most efficient (and perhaps the only) method for systematicallycontrolling the stimulus environment while precisely measuring millisecond-by-millisecondresponses. While the cost of developing this system might be high, the earlier detection ofdementing symptomatology could allow for possible treatments at an earlier course in thedisease process, leading to more informed long-term care and increased functional longevityfor the client.

Following from this last point, a commonly cited advantage of VEÕs is the capacity torecord and measure naturalistic behavior within a simulated functional scenario [28,29]. Thisasset offers the potential to collect reliable data which might have been otherwise lost tomethods employing behavioral ratings from trained observers of behavior in ÒrealÓ worldsettings. However, behavioral observation methods which make use of video recordings forlater rating, may be sufficient for certain purposes. For example, this may be the case with theassessment of Òrough and tumbleÓ play that is commonly focused upon in comparisons ofgender differences in children as well as with the study of aggressive behavior [30,31]. Theassessment of these behaviors within a simulated environment would require a strong tactileand physical interaction component that is not currently possible in a VE. While it may bepossible to design VEÕs with the capacity to stimulate these activities, the absence of the tactilefeedback loop from actual physical contact (as well as the practical issues of using an HMDwith this level of gross motor activity), makes a real world application, a relatively simplerand more effective environment for this purpose. By contrast, a VE designed to measureresponses to cognitive challenges within a simulated classroom by children diagnosed withattention deficit/hyperactive disorder may fare better. With this sort of application, the primarytechnical emphasis is on the precise delivery of cognitive challenges (i.e., instructions given,questions to answer, etc.) and distracters (i.e., ambient noise, movement others, seatingposition factors) in both a sequential and simultaneous fashion. VEÕs would be particularlysuited for the stimulus delivery component of this scenario, and would be capable ofmeasuring important target responses such as head turning, ÒfidgetingÓ in the seat, andcognitive task performance. These behaviors could be analyzed in relation to the complexpatterns of stimulus delivery beyond what would be possible with a behavioral observationteam in an actual classroom.

For cognitive rehabilitation purposes, the same Òelegant simplicityÓ reasoning holds.Certain types of critical thinking training approaches may be more efficiently administered to aperson with a mild head injury by utilizing preserved reading comprehension skills tohierarchically teach reasoning by analogy. This is a relatively straight-forward approach thatthe client can practice at home, as well as in a treatment setting. This sort of language/logicprocess is viewed as less amenable to a VE approach at the current state of the technology andthis is discussed further in the next section. However, if the client has impairments in areasrelating to active problem-solving and executive functions, then VR-delivered scenarios thatallow for exploration and interaction within a dynamic simulated functional environment could


potentially offer hierarchical challenges that couldnÕt be presented efficiently and consistentlyusing traditional methods.

In summary, the examples cited above were chosen to illustrate the Òelegant simplicityÓcriterion applied to a range of possible applications. This first step in the VE decision makingprocess requires one to justify the selection of this technology in contrast to simpler, alreadyavailable tools. If the application meets this criterion, and is expected to add value to alreadyexisting approaches via the assets that are available with VEÕs, then it is time to examine thespecifics of the application in light of the following issues. Some of the VE examples citedalready, will be revisited again in later sections when seen to be relevant to those issues.

3 . How well do the current attributes of a VE fit the needs of thepsychological approach or target?

As can be seen in the previous section, it is recommended that value added VE applicationsbe developed that avoid the redundant development of something already existing in a simplerform. The selection of appropriate psychological targets is inextricably related to this, but requiresan additional understanding of the match, or Ògood fit criterionÓ, between these targets and thecurrent capabilities of VE technology. At the present time, VEÕs can be said to offer certainspecific ÒattributesÓ(or ingredients) that would seem to be well matched for certain types ofMH approaches. In general terms, these include such fundamental attributes as:

1. the capacity to provide exposure.2. the capacity to provide ÒactiveÓ distraction.3. the capacity to expose subjects to precisely administered, dynamic, 3-D, visual and

auditory stimuli.4. the capacity to involve a person within an interactive procedural activity.

Each of these attributes, alone and in combination, can be exploited in a VE to addresscertain psychological targets in ways that could add value beyond what already exists withtraditional approaches. These are also the ingredients in current applications that have shownsome of the best initial effectiveness thus far at this early stage of VE development.

The clearest example of a body of work that exploits these attributes is in the VEapproaches that target fear and anxiety reduction via an ÒexposureÓ model. Traditionalbehavioral therapies for the treatment of phobias have used exposure to fear or anxietyprovoking stimuli as a prime component of treatments variously termed, systematicdesensitization [32], implosion therapy [33], flooding [34], and in approaches employingbiofeedback [35].

While each of these techniques are based on differing viewpoints on the necessity ofconcurrent relaxation, use of imaginal vs. actual stimuli, and the underlying mechanisms ofchange (reciprocal inhibition vs. extinction), the one constant is the presence of some type ofexposure to the ÒcontrollingÓ or feared stimuli. VE systems designed to address fear reductioncontain environments that allow for hierarchical exposures to the feared stimuli that can besystematically presented (attributes 1 & 3), contingent on the clientÕs progress. They alsoallow for naturalistic exploration and some interaction with the feared stimuli (attribute 4).While in the presence of the feared environment, clients can be induced to relax so as toreplace fear with the more therapeutic response of relaxation via reciprocal inhibition. Evenwithout the relaxation component, fear might be expected to decrease via an extinction processwhich occurs simply by being exposed to the feared stimuli in the absence of anyunconditioned consequence. VEÕs are well matched to the needs of these exposure basedpsychological approaches. Phobic clients are more willing to expose themselves to the fearedstimuli within the ÒsafetyÓ of a VE, in stark contrast to their avoidance of them in real life.They also exhibit similar fear related physiological responses while in the VE, which diminishover repeated exposures [B. Wiederhold, personal communication, July 7, 1998].


The initial reports of success with this work have encouraged researchers to address otherdisorders thought to be amenable to exposure methodologies such as Post Traumatic StressDisorder [7,36] and Obsessive Compulsive Disorder [36]. These applications are examplesof VEÕs that have Ògood fitÓ with the needs of the therapeutic approach that they areattempting to improve upon. In light of the substantial occurrence, high profile, anddebilitating nature of these disorders, positive results using VEÕs could serve to raisecredibility in the eyes of mental health professionals unfamiliar with the technology, andbenefit the field as a whole.

It may be noted that the above list of VE attributes does not include mention of forcefeedback of tactile and proprioceptive information. While force feedback is viewed as apotentially valuable asset, the technology to deliver this component is not seen to be ready atthe current time for it to be considered an attribute by which one should base their decisionmaking for choosing a VE for a MH application. However, a creative exception to thisobservation has been seen in the VE/phobia literature and should be noted. In a recent casestudy of a VE applied with a spider phobic, the client was able to ÒhandleÓ a rubber spider inconjunction with being exposed to HMD-delivered spider presentations [3]. While this mayhave added some incremental value to the fear reduction that resulted, it is not possible todiscern this from the design used in this study.

Another newly emerging set of applications, which appear to meet the Ògood fitÓ criterion,have addressed the use of VEÕs as a form of ÒactiveÓ distraction (attribute 2) for pain andstress management with burn and cancer patients [8,9,37,38]. The distracters used with theseapproaches are designed to involve the patient in an interactive VE in order to draw attentionaway from the perception of pain or the cues present in a stressful environment. (This mightbe contrasted with a ÒpassiveÓ distraction methodology that involves the patient in simplyviewing a videotape or other such presentation. Some dentists now offer cartoons to childrenvia ÒTV-glassesÓ as a form of ÒpassiveÓ distraction to reduce pain). For example, one casestudy reports that burn victims requiring repeated dressings of their wounds (on a daily basis)have displayed a reduction in pain when actively involved in using a VE during the procedure[3]. This HMD application not only produces a ÒdistractiveÓ environment, but is also seen toprovide a means to restrict the visual presence of conditioned stimuli (treatment roomsituation) which are said to be learned precursors leading to a heightened pain response.Another VE ÒdistractionÓ approach has been developed, which also features an additionalrehabilitative physical activity component [9]. In this application, foot pedals, at the end of thepatientÕs bed, can be operated which allows the patient to ÒwalkÓ through a virtual forest andmay serve to encourage therapeutic physical activity that would otherwise be difficult tomotivate, as well as provide some measure of stress reduction.

Support for these approaches can also be found in a controlled study using a non-HMDflatscreen approach, investigating the effects of Òvirtual reality enhanced exercise equipmentÓon exercise adherence and feeling states [39]. This report showed significantly better resultson these target variables for subjects exercising within the VE, compared to a non-VEcondition. The authors suggested that the VE experience promoted a ÒdissociationÓ from theexercise-caused bodily discomforts and that this was related to improved adherence andpositive feelings towards the experience of exercise. These early studies suggest a Ògood fitÓbetween VE applications and therapeutic approaches designed to reduce pain perception andpromote rehabilitative activity utilizing distraction. While these applications may not replacestandard techniques for chronic day-to-day pain management, a ÒdistractingÓ VE could provequite valuable in specific situations where extreme pain may interfere with immediate treatmentprocedures, patient comfort, rehabilitative activities, and the healing process. Also, it will beimportant to compare pain reduction ratings for an ÒactiveÓ VE approach with that of simply usingother more passive distracters, such as simple ÒTV glassesÓ. This question involves anassessment of the additive value of VE immersive and interactive characteristics to enhancedistraction, and these factors will be discussed in more detail in section 5 of this chapter, onÒpresenceÓ.

Certain neuro-psychological applications also appear to manifest Ògood fitÓ with theattributes of a VE. These applications rely less on simple stimulus exposure and distraction,and benefit more from the capacity for subjects to be presented with precisely administered


dynamic, 3-D, visual and auditory stimuli (attribute 3). When this is coupled with the capacity forinteractivity (attribute 4), the potential exists to create useful cognitive assessment and trainingenvironments. VEÕs could also be designed which mimic real world challenges without the lossof experimental control that often occurs in naturalistic settings [28]. These basic attributes appearto provide the necessary ingredients for VE neuropsychological applications in a number ofareas.

As described in the previous section, applications for the assessment of attentional abilitiesappear to be an area where unique and value added VE approaches currently appear possible.Traditional rehabilitation methods applied to this set of cognitive processes have shown promise,but are quite labor intensive to administer (40). A virtual approach would be capable ofsystematically presenting simultaneous/sequential stimulus challenges (attribute 3) in order to testand train attentional components in a complex manner that is not possible using traditionalmethods. The attributes of a VE would appear to fit well with the needs for precise stimuluscontrol and response measurement that are required for attention-targeted applications.

This reasoning also holds for VEÕs designed to address problems with the higher levelattentional control required for the cognitive domain referred to as executive functions. Thesefunctions generally refer to ÒÉa set of behavioural competencies which include planning,sequencing, the ability to sustain attention, resistance to interference, utilization of feedback,the ability to coordinate simultaneous activity, cognitive flexibility (i.e., the ability to changeset), and, more generally, the ability to deal with novelty.Ó [pp. 209, 41]. The complexity ofthis cognitive process makes assessment and rehabilitation a questionable process usingtraditional psychometric methodologies [42]. However, as with the attention example citedabove, the attributes of a VE offer a unique capacity to address these functions. In fact, arecent paper has reported success using a VE to more accurately specify these deficits in ahighly educated patient two years following a stroke [43]. In this case study, a VE wassuccessful in detecting deficits that had been reported to be limiting the patientÕs everydayperformance, yet were missed using traditional neuropsychological tests (i.e., WisconsinCard Sorting Test).

Visuospatial assessment/rehabilitation is another area that is particularly well matched withthe unique stimulus/response assets of a VE. The capacity to design 3-D objects that can bepresented in a specific and consistent manner, and manipulated by the user contingent upon avariety of task demands, could be a powerful tool for these applications. This direction wouldprovide a unique approach for the assessment and rehabilitation of persons with visuospatialimpairments in the areas of unilateral neglect, spatial navigation, mental rotation, visuomotorintegration, imagery, spatial relations, and spatial memory. These are common sequelae fromhead injury, stroke, and some neurodegenerative disorders. Traditional methods applied tothese areas rely mainly on pencil and paper materials and flat-screen computer tasks that arelimited by poor depth and motion cues. VEÕs also offer the potential to address these variablesin an ecologically valid manner (functional simulations). The attributes of a VE appear to bewell matched to these challenges and this is reflected in the number of applications that arecurrently aimed at clinical populations. This work has been conducted, or is in progress,addressing visual neglect [17], spatial awareness [12], spatial memory [16,19,20], and mentalrotation [18].

The MH applications addressed above are not presented as exhaustive of the areas where aVE would be of value. Rather, they are meant as examples of the type of analysis that wehave applied to judging the fit between VE applications and MH targets in this nascent field.Also, we hesitate to address target areas that do not suggest a good match with the attributesof a VE or where the technology is not in a state of readiness to add to what currently existswith traditional methodologies. Our vision of VEÕs may reflect gaps that others do notpossess. However, some examples may be obvious. Many psychotherapeutic approaches arebased on the exploration of personal issues within a therapeutic relationship. While some haveconjectured that VEÕs may be useful for shared experiences by the client and therapist[23,44], further specification on a case by case basis of these applications would be needed tojudge whether the attributeÕs of a VE would match the needs of therapy. Regardingneuropsychological applications, complex reasoning abilities that have heavy requirements for


language based representation and declarative memory may be more difficult to address at thecurrent state of VE development, although may well be possible in the near future.

4 . How does a VE approach match the characteris tics of the target clinicalpopulation?

Awareness of the interaction between treatment strategies and patient characteristicsspecific to different clinical conditions has guided the development of mental healthapproaches for many years [45]. The usefulness of VE applications across different clinicalpopulations also requires the same measured consideration of these characteristics. Clinicalpopulations may differ in areas including: apprehensiveness to use a HMD, reality testing,capacity to learn to operate in a VE, and susceptibility to cybersickness/aftereffects, amongothers. These last two considerations are of such importance that they will be discussed inseparate sections to follow (see sections 6 & 7). Awareness and preparedness for these issuesis necessary for ethical reasons as well as for treatment efficacy concerns. The uniquepsychological, cognitive, and functional characteristics that are commonly seen in differenttypes of clinical conditions need to be considered, along with an informed sensitivity to thevulnerabilities of these groups. The age of the participants may also be a factor that is ofrelevance to decision making regarding the applicability of VE technology. Expected benefitsof using a VE approach need to be tempered by a clinical vigilance for possible unanticipatedconsequences that could limit the applicability of a VE application for certain clinicalconditions. Thus far, the clinical application of VEÕs has appeared to be fairly thoughtful andrational, this possibly owing to both itÕs limited availability, and the professionalism of theinnovators of these early applications. However, as the technology becomes more accessible,individuals who become enamored with virtual methods, but lack a sensitivity to the relevantmental health and ethical concerns, may be in a position to develop VE MH applications. Theresulting systems could be of questionable utility at best, and have the potential to do harm atthe worst. Although incidents where this has occurred have yet to appear in the literature, thepotential exists that these types of events may be overlooked and go unreported.

A number of authors have acknowledged the potential difficulties that could arise with theuse of VEÕs by individuals with certain types of psychopathology [7,46,48]. ClientÕsdisplaying features of various psychotic, bipolar, paranoid, substance abuse, and otherdisorders where reality testing and identity problems are evident, may be ill-advised toparticipate in a VE. When working with patient groups that have the potential for these typesof difficulties, an ethically-based screening procedure is necessary to minimize the possibilityof inducing harmful psychological consequences on the client via a VE approach. Forexample, in the application of a VE designed to address Post Traumatic Stress Disorder(PTSD) in Vietnam veterans, clients are exposed to various battlefield scenarios that includeintense visual and auditory stimuli. As with non-VE approaches using various forms ofmedia, imaginal, and in vivo techniques, this type of ÒtherapeuticÓ exposure in a VE, isexpected to be of value in the treatment of this disorder. However, the client can be expectedto experience considerable stress during the course of this treatment. The group that isdeveloping this VE approach has prudently implemented a procedure to screen out clients whomight be at risk with this type of treatment. Prior to actual VE participation, clients are seenfor four sessions, during which they are thoroughly screened for any indicators of psychotic,manic, and substance abuse features. Only after the client is assessed to be appropriate for thistype of treatment are they allowed to participate in these intense VE scenarios! In essence, theethical principles that serve as guidelines for the standard practice of conventional therapymust be stringently applied for VE applications [B.O. Rothbaum, personal communication,June 30, 1998].

Likewise, it is essential to anticipate possible difficulties that could arise due to specificcharacteristics that exist for persons with CNS dysfunction and resulting neuropsychologicalimpairments. While it is the cognitive impairments that are most often focused on with thesegroups, significant emotional, social, and identity difficulties commonly exist within the totalpattern of the resulting disability. The sheer complexity of factors that contribute tocognitive/functional impairments and the possible treatments used to address CNS disorders


make a thorough analysis of these issues beyond the scope of this chapter. However, thesame clinical sensitivity that is required for the more pure psychological diagnoses should beapplied to decision making for VE applications with these groups. For example, orientationand equilibrium difficulties are often common sequelae with CNS dysfunction and properscreening guidelines are of vital importance in this regard. Thus far, VE applications thattarget these groups addressing functional skills [13], memory [16,20], spatial skills[12,19,18], and executive functioning [43] appear to be relatively benign and this may reflectthe appropriate caution seen in the development of these applications. As the field developsfurther and more objective results become available, we will be in a better position toformalize the advisementÕs and proscriptions for VE use with both psychological andneuropsychological populations. Until that time, rational caution mixed with thoughtfulsensitivity to these issues will be required in order to ethically advance these applications!

Regarding age related issues, there appears to be a developing literature on VE applicationswith young populations [11,12,13,15,19,38]. Youthful populations, having grown upduring the age of computer and video games, may be more Òat homeÓ with VE set-ups. Thereports to date mainly involve the training of a functional skill involving the learning of thespatial characteristics, and functional consequences, of a target environment, and requiringnavigation within it. For example, children with cerebral palsy and other types of motorimpairments have been trained to operate motorized wheelchairs in HMD virtual environmentswith reported success [11]. Spatial awareness has also been trained in children with similarmotor impairments using a non-HMD VR simulation of important landmarks(i.e., fire exits,bathrooms, etc.) in a school building [12]. The childrenÕs capacity to orient successfully tothe landmarks was shown to successfully generalize when tested in the actual building.Similar findings were also reported for teenagers with developmental disabilities for asupermarket search and navigation, non-HMD training system [13]. These studies suggestthat VR cognitive/functional applications can be usefully applied to these age/clinical groupswith improvements seeming to generalize to real world functional tasks.

The initial concerns that children might have difficulties adjusting to an HMD did notappear to be borne out in some of these more ÒcognitivelyÓ oriented studies. For example,positive results have been reported on training autistic children Òstreet-crossingÓ skills usingan HMD VE [15]. Although one report [11] mentioned that for a VE wheelchair navigationtraining application with young children, many of the users had a preference for using a largeTV monitor instead of the HMD, with no reported decrease in performance or interest. Also,the occurrence of symptoms of cybersickness and aftereffects have not been reported to beproblematic with these younger populations. However, systematic assessment of this has notoften occurred and should become a mandatory component of all VE investigations.

No studies have reported on VEÕs specifically designed for children with psychological,emotionally, and social difficulties, although the potential for these applications has beendiscussed[49]. Further study of VE applications with young populations would appear to beof some value, particularly in light of the encouraging initial results reported with the spatialapplications. These applications have shown the potential for positive impact on thesechildrenÕs future chances for functional independence. Also, since the peak incidence foracquired brain injury is with the 15-24 age group, it would appear that many ÒyouthfulÓpersons could potentially benefit from VE cognitive/functional applications and this groupshould also be targeted for this purpose.

On the other end of the age continuum, it is puzzling to note that no studies have beenreported on VE applications for older populations (over 65). Relevant issues for this agegroup could include limiting factors due to visual difficulties, mobility and balance, andsusceptibility to cybersickness and aftereffects. Our search also found a similar dearth ofresearch with this older population even within the general simulation technology literaturewhich could have provided some direction for VE development. One study compared normalelderly with early AlzheimerÕs patients on automobile driving using the Iowa DrivingSimulator and found significantly more accidents with the AlzheimerÕs group [50]. However,no information regarding the incidence of simulator sickness or other complications wasreported. Another group is currently examining the effects of caffeine and nicotine on theperformance of experienced pilots up to age 65 in an aircraft simulator (J. Yeasavage,personal communication, March 21, 1997), but the results from this work is not yet available.


The rapidly increasing size of the aging population, coupled with age-related changes incognitive/functional performance, makes investigations into the feasibility of VE neuro-psychological applications with elderly populations of considerable importance. Research into thisage groupÕs susceptibility for cybersickness and aftereffects (see Section 7) would be a usefulstarting point for this area. If these side effects were not found to be problematic, VE applicationscould be of particular utility for the assessment of cognitive impairments due toneurodegenerative disorders with this age group. Our lab is currently conducting a study withan elderly population (65+) on a VE spatial rotation assessment and training system[18] whichwill examine feasibility components in detail, in addition to performance efficacy on this cognitiveprocess.

While cognitive rehabilitation approaches for progressive disorders such as AlzheimerÕsdisease have met with limited success, VEÕs designed to deliver functional training for elderlypopulations might be of value. Functional VEÕs which exploit preserved procedural learningabilities in a relatively safe environment could serve to help maintain adequate performance ofactivities of daily living needed for safe living and functional independence. Preventable falls,and the hip damage that often accompanies them, are a leading cause of the loss of functionalindependence with this population. In this regard, a VE system is currently being developedto train elderly subjects to step over obstacles [51]. This HMD VE application allows at-riskelderly persons to practice stepping over moving obstacles on a treadmill while wearing anoverhead safety harness. As such, an effective VE approach to address this basic skill wouldbe of considerable value. Results from this study may also shed insight into the feasibility ofVE approaches for other procedural skills with elderly groups. However, procedural trainingapproaches may be of limited value for elderly persons with certain neurodegenerativedisorders. For example, individuals with HuntingtonÕs disease, often manifest difficultieswith procedural learning [52]. These patients may not be able to benefit from a highlyprocedural virtual learning environment. However, VE applications for this group might beusefully aimed at assessing the decline of this type of Òhands-onÓ learning as a tool formeasuring disease progression or the effects of different treatment approaches.

The application of VEÕs with MH populations offers the potential to create assessment andtreatment scenarios, that were not possible in the past. With this new capacity to createÒaltered realitiesÓ comes the responsibility to anticipate possible negative consequences thatcould do harm to potentially vulnerable populations. It is essential that individuals who developand implement VEÕs with MH populations be fully aware of the current status of conventionalapproaches with the population with which they are working. This also requires an understandingof the consensually recognized strengths and limitations of the specific target population. It is alsorecommended that incidents where a negative reaction to a VE occurs, be documented and sharedwith the VE community. In this manner, the causes of these problems can be addressed andunderstood, and future methods to prevent the reoccurrence of such problems can be developed.

5 . What is the optimal level of presence necessary for the application?

A full discussion of the human factors issues pertaining to the concept of presence isbeyond the scope of this chapter and is available elsewhere [25,53-56]. However, issuesregarding presence will be briefly addressed here, as they seen to be relevant for theconceptualization and design of VEÕs for MH applications.

The concept of presence is often cited as one of the important features of a virtualenvironment [25,57,58,59]. Presence can be simply described as the experience a person haswhen in a VE of Òbeing thereÓ. Stated another way, presence is ÒÉthe subjective experienceof being in one place or environment, even when you are physically located in anotherÓ[pp.225, 56]. This experience is not restricted to VEÕs; reading a book, watching TV, andtalking on the phone can all engender some level of presence. These authors further suggestthat the psychological states of Involvement and Immersion are both necessary for theexperience of presence. Involvement results when a person selectively focuses attention andenergy on coherent stimuli, activities, and events and can depend on the degree of meaning andsignificance that the person attaches to the activity, in addition to the ÒcompellingÓ nature of theactivity. Immersion is seen as related to oneÕs perception of being enveloped by, included in, and


interacting with environments that provide a continuous stream of stimuli and experiences [56].Involvement seems to be more a function of the userÕs internal characteristics (interest,motivation, etc.)and immersion appears more related to system attributes (non-HMD vs. HMD).However, these characteristics are seen to operate in an interdependent fashion, and both arebelieved to be necessary ingredients for the experience of presence to occur [56].

There is currently no single agreed upon way to measure presence, and a variety ofapproaches have been proposed or developed utilizing both, subjective reporting (rating scales[56,60], method of paired comparisons [61], and cross-modality matching [62]) and objectivemeasures (physiological monitoring [63], automatic motor responses [64,65]). A number ofvariables have been conjectured that may influence presence and these include: ease ofinteraction, degree of user-initiated control, pictorial realism, length of exposure, socialfactors, and system factors [25]. However, research examining the relationship betweendifferent levels of presence and VE effectiveness (particularly generalization or transfer fromthe VE to the non-VE world) for various types of applications is still at an early stage.Positive relationships have been reported for tracking performance [66], search tasks [67],while mixed results have been found on simple psychomotor and spatial knowledge tasks[56,68]. For those interested in a more in-depth presentation and analysis of these issues, anexcellent review paper produced by a 25-member roundtable panel conducted at the SeventhInternational Conference on Human Computer Interaction is available and is highlyrecommended [25].

For the purposes of the present chapter, we will examine the concept of presence and howit may relate to the potential effectiveness of various MH VEÕs. An understanding of thefactors involved in this relationship may be important for predicting the relative value ofpresence for different MH applications. Awareness of the nature of presence factors that areunder our control in the design of MH VE systems could serve to guide and inform futuresystem development. This knowledge does not exist at this early stage in the study of MH VEapplications, but it is safe to say that different MH targets will likely have different optimalpresence requirements. To determine this will require an analysis of presence/effectivenessrelationships for a range of different target applications.

Intuitive thinking regarding VEÕs might suggest that a large ÒamountÓ of presence wouldbe necessary for effective MH scenarios and that this may require a high degree of realism.However, the capacity to develop veridical VE scenarios that absolutely match thecharacteristics of the ÒrealÓ world, and which might be expected to create more presence, isnot technically feasible at the current time (and may never be). Fortunately, the experience ofpresence is not totally dependent on the level of realism [69]. An extreme level of VEsimilarity with the real world may not be necessary for the experience of presence to occur,and for MH VEÕs to be effective.

In the process of conjecturing on the value of presence for MH VE effectiveness, it may beuseful to consider the immersive and involvement components of presence [56] and howdifferent weightings of these factors may impact the effectiveness of various applications. TheÒsuspension of disbeliefÓ that occurs when one is using a virtual environment appears in part,due to system factors (i.e., HMD vs. non-HMD, graphic quality, computer speed, etc.) andto the individual differences of the user (i.e., degree of claustrophobic concerns, capacity fora good visual imagination, past experience with VEÕs, etc.). The design of an effective MHVE requires a unique appreciation for the complex relationship between available equipment,MH targets, and the characteristics of the clinical population. For example, psychological VEapplications for fear reduction with phobic clients have been shown to be effective eventhough the scenarios are often somewhat ÒcartoonishÓ and would never be mistaken for thereal thing. However, the effectiveness of these scenarios may be found to rely more on theHMD-based immersion component of presence, than on an involvement component. By this,it is meant that for persons who have a long history of avoiding feared stimuli, a highlyimmersive HMD system may be necessary to keep their awareness directed toward themodeled stimuli (immersion promoting involvement) in order to encourage therapeuticexposure. These clients would not be expected to naturally be motivated to experience thestimuli (low involvement), and therefore a less immersive non-HMD flatscreen system forthis application may fall short of the level of presence needed for effective therapeuticexposure to occur.


However, a HMD may not necessarily be mandatory as a way to achieve an effectivepresence level. This issue may need to be considered in terms of the potential contribution topresence levels by other non-visual sensory stimuli. For example, it has been noted thatÒbattlefieldÓ sounds make for very compelling stimuli in VEÕs designed to address PTSD withwar veterans [B.O. Rothbaum, personal communication, June 30, 1998]. Perhaps a non-HMD multi-wall cave system that integrates this type of sound stimuli with the standard visualmaterials, may create an effective level of presence for the targeted purpose. This hypotheticalexample may serve to illustrate the potential for creating an acceptable level of presence withoutthe more immersive components available with HMD technology. Also, navigation studies havealso shown successful functional skills learning (supermarket shopping and landmarkrecognition) using a flat screen computer approach for teenagers with developmental disordersand children with motor disorders.[12,13] These results suggest that for certain populations andtraining objectives, a HMD may not always be necessary. However, HMDÕs may still be themost efficient tool to support the immersion-based component of presence and may benecessary for VE effectiveness with certain MH targets. Examples of areas where theimmersion component of presence found with HMD-based systems may be especially usefulmight include:

1. Systems designed to produce active distraction where the goal is to ÒremoveÓ thepersonÕs ability to view conditioned (and unconditioned) pain related stimuli [8].Anticipated pain reduction may also serve to motivate a patient to become ÒinvolvedÓ inthis alternative experience, with a higher level of presence resulting.

2. Systems designed to allow comparisons and ratings of full-sized humans for purposesof assessing and treating body image disturbances [10], or for other applications thatmay require some interaction with virtual ÒactorsÓ.

3. Systems that target the assessment and rehabilitation of attention processes (as well asother cognitive domains) whereby HMD fostered immersion would be needed to eliminateexternal ÒdistractionsÓ that would intrude on the controlled environment [5,70].

4. Systems designed to assess and rehabilitate functional activities where transfer to thereal world is highly valued. An example where a higher level of the sense of presencemay be needed to maximize ecological validity, is when the objective is the assessmentor training of a complex procedurally-based functional skill (i.e., driving ability).However, it should be noted that non-HMD approaches have shown some success forthis purpose for simple navigation-based activities [12,13].

This list is not meant to be complete, but rather to illustrate examples where the immersioncomponent of presence is emphasized. Some MH VE applications may exist where theimmersive component is less important, and involvement can be promoted to support a levelof presence that may be necessary for VE effectiveness. This is obviously seen with flatscreencomputer games that create a sense of presence due to their involving features (gaming,interesting graphics, sound effects, etc.). Likewise, less immersive VEÕs may effectivelyaddress certain MH targets by leveraging the involvement component of presence that mayoccur with certain 3-D interactive applications. However, the users in the targeted clinicalgroup may need to possess more motivation to participate and have intact attentional abilitiesin order to benefit from less immersive approaches.

VE applications that target visuospatial processes and specific motor abilities may beusefully addressed in this manner [18,71,72,73]. In this regard, our lab has developed amental rotation/spatial skills assessment and training system that utilizes the Immersadesksystem [18]. This system is a drafting table format virtual prototyping device that employsstereo glasses and magnetic head and hand tracking. It is a projection-based system offering atype of VE that is semi-immersive and features a 4 X 5-foot rear-projected screen positioned at a45 degree angle. The size and position of the screen give a wide-angle view and the user is able tolook down as well as forward. We have designed block configurations that appear like hologramsÒfloatingÓ in front of the user. The goal of the application involves the specific testing and trainingof eye/hand rotations of the blocks, into specific targets with an aim towards measuring andimproving mental rotation ability. Unimpaired subjects that have been tested, report the task to beengaging (involvement), and distraction away from the screen rarely, if ever, occurs. Positive


transfer effects seen thus far may suggest that for this purpose, this type of presence (lowerimmersion-higher involvement) is acceptable for the goals of the application. However, trialswith impaired populations have not yet started, and the effectiveness of this application for thosegroups remains to be seen.

How much presence is necessary for a given application remains an empirical question. Inorder to determine the factors that influence presence and how they relate to the effectiveness ofthe application, considerable work need to be done. The lack of an agreed upon standard methodto measure presence limits our capacity to understand itÕs relationship with system effectiveness.However, a set of rating scales designed to measure both, presence, and an individualÕsÒimmersive tendenciesÓ has been developed and initial reports suggests that they are internallyconsistent and have high reliability [56]. These tools have also been shown to provide, ÒÉaweak, but consistent positive relation between presence and task performance in VEÕsÓ [pp. 225,56]. Perhaps this relatively low cost approach to measuring these factors will provide usefulinformation which will aid in the design and development of effective MH VEÕs.

6 . Will the target users be able to learn to navigate in and interact with theenvironment in an effective manner?

The method of navigation and requirements for interaction in a VE, are important factors toconsider in the design of these systems for MH applications. While this topic might normallybe subsumed under the last section on the issue of ÒpresenceÓ, it is felt that the specificnavigation/interaction user issues for MH applications requires separate treatment. Virtualreality has been characterized as an Òintuitive interfaceÓ that allows a person to interact with acomputer (and data) in a naturalistic fashion [21]. In this regard, Wann and Mon-Williamssuggest, ÒThe goal is to build (virtual) environments that minimize the learning required tooperate within them, but maximize the information yield.Ó [p.845, 55].

Thus far, this has been less of an area of difficulty for VEÕs designed to addresspsychological targets for individuals with ÒintactÓ cognitive processes. Applications directedtoward the exploration of fear or anxiety provoking environments (as well as with theÒdistractionÓ approaches) have been able to use various hand actuated devices such as wands,joysticks, and data-gloves with relative effectiveness. In these sorts of applications theÒintuitivenessÓ of the mode of navigation, and interaction with objects, appears to be less of aconcern for the overall effectiveness of the VE in addressing the targeted objectives. After afew practice trials, subjects appear able to learn how to effectively move around in theenvironment at a level that meets the needs of the application. In fact, for some applications,the need for independent navigation and interaction, is less relevant. This can be readily seenwith applications designed to address fear of flying [2,4]. In these applications, all that isrequired of the subject is that they sit in the virtual aircraft seat and experience the flyingscenario without any need for navigational control.

However this Òinteractional intuitivenessÓ issue becomes more relevant when designingVEÕs applied to personÕs with cognitive, and in some cases, motor impairments. In order forpersonÕs with cognitive impairments to be in a position to benefit from a VE, they often mustbe capable of learning how to navigate within the environment. Many modes of VE navigation(data-gloves, joy sticks, space balls, etc.), while easily mastered by nonimpaired participants,could present problems for those with cognitive difficulties. Even if patients are capable ofinteracting in a VE system at a basic level, the extra non-automatic cognitive effort required tonavigate may serve as a distraction, and limit the targeted assessment and rehabilitationprocesses. In this regard, Psotka [74] hypothesizes that facilitation of a Òsingle egocenterÓfound in highly immersive interfaces serves to reduce Òcognitive overheadÓ and therebyenhance information access and learning. Thus far, early reports on VEÕs with neurologicalpatient populations using both joystick HMD and non-HMD systems have producedencouraging results. In these studies, assessing executive functioning in head injured patients[43,75], teaching supermarket navigation with developmentally disabled students [13], andteaching spatial skills in children with cognitive and motor impairments [12], difficulties withlearning to navigate in the VEÕs were not reported. However, navigational/interactional factorswere not the empirical focus of these studies and it might be expected that as VEÕs are designed


to address more complex cognitive and functional targets, this may become more problematic. Inthese cases, more naturalistic modes of navigation/interaction may be required to optimizeperformance and improve access for patients having severe cognitive or motor impairments. Theuse of voice recognition technology may also be a useful approach for some types of navigationor interaction [76]. This technology may also provide a more naturalistic interface on sometypes of tasks, in addition to improving VE access for persons with motor impairments.

Another factor of critical importance, is whether the means of navigation actually affectswhat aspects of the VE are focused on, and consequently what is measured and learned. Thiswas seen to be the case in a study that looked at what types of memory were enhanced in anunimpaired group during a four-room house navigation task [16,20]. These studies, usingboth a HMD and non-HMD joystick interface, allowed one subject to navigate the house(active condition), while a yoked subject was simply exposed to the same journey but had nocontrol (passive condition). Differential memory performance between the two groups wasobserved, with the active group showing better spatial memory for the route, while the passivegroup displayed superior object recall and recognition memory for the items viewed along theroute. Mixed results were found on two other non-HMD VE studies in this area, with oneshowing active participation enhancing spatial memory [77] and no difference reported in theother [78]. Perhaps a more intuitive method of navigation may have allowed the active group toperform as well on object memory via a more equal allocation of cognitive resources. Also, thisnavigation method may have taxed the subjectsÕ divided attention capacity and thereby influencedthe memory results found using this paradigm. These issues may be particularly noteworthy forthe development of VEÕs designed to address the assessment and rehabilitation of attentionprocessing.

Better generalization of learning to Òreal worldÓ performances might also be expected asthe method of navigation and object interaction more closely resembles the requirements of theÒnaturalÓ or target environment. Reduced motivation may also result when a personÕs first VEexperience is characterized as Òmore work than it is worthÓ when confronted with anunnatural or awkward navigational interface. One example of an obvious and effective matchbetween the mode of VE navigation and the real world objective is with the training ofmotorized wheelchair navigation skill in children with cerebral palsy [11]. In this application,the controls for the motorized chair in the virtual application are essentially identical to thecontrols used in the childÕs real world environment. This would be considered an ÒidealÓmatch between the VE navigation mode and the demands of the actual targeted behavior.However, this sort of one-to-one correspondence is relatively rare for VEÕs having morecomplex navigational/interactional demands. It might be interesting to note any difference ineffectiveness that might occur if the learning in this scenario was directed toward the operation ofa standard manually operated chair. More effective transfer of this skill would be expected withthe original VE application and functional target. However, if equal criterion performance wasfound, it might support the idea of the robustness of training with non-identical navigation devicesand would be quite interesting indeed. In essence, the development of more naturalisticinterfaces could be of vital importance for precise assessment and rehabilitative targeting, andcould also have implications for the generalization issues discussed in Section 8.

7 . What is the potential for side-effects (cybersickness and aftereffects) inlight of the characteristics of different clinical groups?

In order for VEÕs to become a useful tool for mental health applications, the potential foradverse side effects needs to be considered and addressed. This is a significant concern as theoccurrence of side effects could limit the applicability of VEÕs for certain clinical populations.While a full chapter is devoted to the issue of VE-related medical side effects elsewhere in thisvolume, we will briefly address these issues here. A recent review of this area [25] suggests anumber of issues that need to be examined in this area and these may be of considerableimportance in the use of VEÕs with clinical populations. These include: Ò(1) How can prolongedexposure to VE systems be obtained? (2) How can aftereffects be characterized? (3) How shouldthey be measured and managed? (4) What is their relationship to task performance?Ó [Pp.6, 25].These questions are particularly relevant to developers of MH VEÕs, as these systems are


primarily designed to be used by personÕs with some sort of defined diagnosis or impairment.The possibility exists that these users may have increased vulnerability and a highersusceptibility to VE-related side effects, and ethical clinical vigilance to these issues isessential.

Two general categories of VE-related side effects have been reported: cybersickness andaftereffects. Cybersickness is a form of motion sickness with symptoms reported to includenausea, vomiting, eyestrain, disorientation, ataxia, and vertigo [79]. Cybersickness isbelieved to be related to sensory cue incongruity. This is thought to occur when there is aconflict between perceptions in different sense modalities (auditory, visual, vestibular,proprioceptive) or when sensory cue information in the VE environment is incongruent withwhat is felt by the body or with what is expected based on the userÕs history of Òreal worldÓsensory experience [80]. Aftereffects may include such symptoms as disturbed locomotion,changes in postural control, perceptual-motor disturbances, past pointing, flashbacks,drowsiness, fatigue, and generally lowered arousal [81,82,83,84,85]. The appearance ofaftereffects may be due to the user adapting to the sensory/motor requirements of the VE,which in most cases is an imperfect replica or the non-VE world. Upon leaving the VE, thereis a lag in the readaptation to the demands of non-VE environment and the occurrence ofaftereffects may reflect these shifts in sensory/motor response recalibration. It has beensuggested that side effects can be reduced via gradual repeated exposures to VEÕs and by theprovision of more optimal levels of user initiated control over movement in the virtualenvironment [86]. However, these issues need to be investigated further in order to determinewhat effective methods exist to reduce the occurrence of side effects that could limit thefeasibility of VEÕs for MH applications.

The reported occurrence of side effects in virtual environments varies across studiesdepending upon such factors as the type of VE program used, technical drivers (i.e., vection,response lag, field of view, etc.), the length of exposure time, the person's prior experienceusing VEÕs, active vs. passive movement, gender, and the method of measurement used toassess occurrence [84,87,88,89,90,91]. Recent reports also suggest that the profile of sideeffects for virtual environments is somewhat different than those found with flight simulatorsor with sea or air sickness [25,86]. These authors report a unique symptom profile for virtualenvironments which produces more disorienting effects, followed by neurovegativesymptoms (i.e., nausea), and fewer oculomotor-related disturbances (i.e., eyestrain). Theysuggest that these issues need to be understood and evaluated since the total severity ratingsfor virtual environments are usually higher than with other types of simulation technology. Inone study, 61% of 146 healthy subjects reported Òsymptoms of malaiseÓ (i.e., dizziness,stomach awareness, headaches, eyestrain, lightheadedness, and severe nausea) at some pointduring a 20-min. immersion and 10-minute postimmersion period [89]. While a paper on VRtraining for the Hubble telescope repair ground crew [92] suggested low incidence ratesdepending on the symptom (5-40%), a recent study reported a 95% occurrence of some illeffects [91]. For those interested in more details on VE-related side effects and other relevanthuman factor concerns, a number of informative reviews are available [25,54,55,90].

The incidence of side effects is of particular importance when considering the use of VEÕs forMH applications. Thus far, most psychological applications appear to use short periods ofexposure (10-20 minutes) and this may have served to mitigate the occurrence of side effects.However, this is difficult to ascertain, as statistics on the occurrence of side effects withpsychological applications have been inconsistently reported in the published literature to date. Thisis an aspect of data reporting on VEÕs that should be changed. Some type of assessment andreporting of VE-related side effects, whether using Òin-houseÓ designed ratings scales, orstandardized subjective and objective measures [93,94], should be standard procedure for presentingresults on systems in this area.

Particular concern may be necessary for neurologically impaired populations, some ofwhom display residual equilibrium, balance, and orientation difficulties. Also, it has beensuggested that subjects with unstable binocular vision may be more susceptible to post-exposure visual aftereffects [95]. In one of the few reports to date which reports side effectoccurrence with clinical populations, 11 neurological patients were compared with 41 non-neurological subjects regarding self-reported prevalence of side effects [75]. Subjects weretested in a system which was specifically designed for the assessment and rehabilitation of


executive cognitive functioning following brain injury. The results suggested a reducedoccurrence of VE related side effects relative to other studies using the same assessmentquestionnaire, with an overall rate of 17% for the total sample. The authors also reported thatthe neurological subjects appeared to be at no greater risk for developing cybersickness thanthe non-neurological group. While these initial findings are encouraging, further work isnecessary to specifically assess how the occurrence of side effects is influenced by factorssuch as, the type and severity of neurological trauma, specific cognitive impairments, priorVE exposure, length of time within the VE, and characteristics of the specific VE program.This is an essential step in determining the conditions where VEÕs would be of practical valuein the area of neuropsychological assessment and rehabilitation.

A useful tool for monitoring VE-related side effects is the Simulator SicknessQuestionnaire SSQ [93]. While more involved ÒobjectiveÓ measures may exist, particularlyfor the measurement of aftereffects, SSQ data is relatively simple to collect and it may serve asa low-cost method to begin to specify the occurrence of side effects in MH VEÕs. Until wehave better data on these issues, extra caution may be needed with some applications. Forexample, in our work, we will soon be conducting a study with an elderly group (+65 yearsold) using our mental rotation/spatial skills system. Since we couldn't be confident regardingthe absence of potential perceptual aftereffects occurring with this group, we have money builtinto our grant to provide transportation to and FROM the test site. The worst thing for theuser, us, and the field would be for an elderly person to have an car accident driving homeafter participating in an Òexperimental virtual reality settingÓ where we were exposing subjectsto visuospatial manipulations! These concerns need to be addressed in order to assure apositive course for developing VE applications for persons with MH concerns.

8 . Will assessment results and treatment effects generalize to the ÒrealworldÓ?

A fundamental issue which has important implications regarding the ultimate utility ofVEÕs for MH applications is the concept of generalization of measurement and treatment. Ina ÒclassicÓ review from the applied behavioral psychology literature, Stokes and Baer placestrong emphasis on the need to plan and program for generalization when designingassessment and treatment interventions [96]. This is no less important for the design andimplementation of VEÕs for MH applications. As VEÕs are developed to assess and treatvarious MH targets, it will become increasingly important to demonstrate that the results havesome relevance or functional impact on usersÕ real world behavior. For example, in thetreatment of various phobias, early data seem to show that fear reductions that are accrued in aVE, generalize to the personÕs real world functional behavior [3,4,6,97]. In these casesclients were able to walk across real bridges, go up glass elevators, ride in aircraft, andparticipate in areas of everyday life in which they were limited prior to VE treatment. Thisevidence of generalization of treatment from the VE to functional activities in everyday livinghas excited researchers and clinicians working in other MH areas with the hope thatassessment and treatment VEÕs can actually produce tangible benefits.

In the area of neuropsychology, improved generalization of assessment and cognitiverehabilitation is viewed as one of the expected benefits of using a VE [22,28,42] Support forthis expectation can first be seen in the predecessor, field of aviation simulator research. In anarticle on theoretical issues concerning generalization and transfer of training from aircraftsimulators, Johnston cites a Transfer Effectiveness Ratio in the aviation simulation research of0.48 [98]. This ratio indicates that for every hour spent in aviation simulator training, one-halfhour is saved in actual aircraft training. However, while it intuitively seductive to assume thatVEÕs are Òjust another form of simulationÓ, and that generalization will be promoted, researchspecific to virtual environments must be examined.

One early study reported that no evidence was seen for transfer from a VR Òpick and placesequence taskÓ to a real world task [99]. However, some authors have noted problems withthe criterion task used in this study regarding itÕs simplicity [74] and reliance on overlearnedcognitive cues not specific to the VE training [54] which may have limited the implications ofthese results. In contrast, an encouraging literature is emerging which provides evidence of


positive learning transfer from virtual training environments to functional tasks. One VEapplication was shown to foster learning of console operations and this learning was shownto transfer to the actual console [100,101]. Spatial navigation training for a complex buildingwas found to generalize by two different researchers [101,102]. In one of these studies, whilereal building training produced slightly fewer Òwrong turnsÓ than the VE training (1.1 vs.3.3), both of these methods were significantly better than the verbal rehearsal condition (9.2errors) [101]. In another study on navigation skills training, soldiers used a self-guidedvirtual terrain environment to successfully learn the actual physical terrain that had beenmodeled [103]. Self-guided HMD VE training for machine operation has also been shown topromote generalization [104]. This project, conducted at Motorola University, is of particularpractical interest, in that the results indicated positive transfer from a virtual ÒfactoryÓ trainingprogram to the actual factory line. Since vocational concerns are paramount in variousrehabilitative domains, evidence of transfer or generalization from a VE to a ÒrealÓ workenvironment, is a very desirable objective.

In studies examining generalization with clinical groups, evidence of positive learningtransfer from a non-HMD virtual training setting was found for groups of developmentallydisabled students and children with motor impairments [12,13]. In one study, students withsignificant cognitive impairments were trained on a PC-based, non-HMD, virtual system tonavigate through and select specific items in a virtual supermarket [13]. In addition todemonstrating good transfer of learning, this study is noteworthy in that it suggests anefficacious approach to increasing the independence of persons with cognitive difficulties forwhom a fully immersive HMD strategy may not be practical. Also, a case study will soon bepresented that reports positive generalization with an amnesic patient who was trained in routefinding around a hospital rehabilitation unit using a non-immersive VE, based on the real unit[F.D. Rose, personal communication, May 19, 1998].

A recent case study also reports positive generalization of results for the assessment ofexecutive functioning [43]. Two years following a stroke, the patientÕs everyday performancewas reported to be impaired, yet traditional neuropsychological assessment tools suggestednormal functioning. By contrast, the VE was better able to detect deficits that had been reported tobe limiting this patientÕs everyday functioning. These findings support the idea that VEÕs may bemore effective for allowing cognition and functional behavior to be tested and trained in situationsthat are ecologically valid. Users could be evaluated and rehabilitated in an environment thatsimulates the real world, not a contrived artificial environment. Results from these types of VEscenarios would be expected to have greater clinical relevance to the personÕs everydayenvironment.

Three types of generalization have been described that have relevance to the design ofsystems and studies investigating the generalizability of MH approaches conducted in VEÕs[105]. These are: (1) transfer of gains on the same materials on separate occasions; (2)improvement on similar but not identical training tasks; (3) transfer from the trainingenvironment to day-to-day functioning. From this framework, a VR application for thetraining of some hypothetical visuospatial ability would show good generalization ifimprovements were seen, across multiple VE sessions, on pencil and paper measures of theskill, and observed in a real life task such as assembling a piece of furniture or finding oneÕsway home. These types of generalization are of similar concern for assessment purposes. Theemphasis on any one of these forms of generalization will depend, of course, on the goals ofthe application. At this stage of VE development, the primary emphasis has been ongeneralization from a VE environment to the actual Òreal worldÓ environment. How well-suited a VE is for this purpose may be related to a variety of factors and these need morestudy with clinical populations. One investigation with non-impaired participants, reportedthat a short period of VE training for spatial navigation of a maze was no more effective thanmap training. However, with longer exposure time, VE training eventually surpassed realworld training [106]. This finding suggests that temporal parameters need to be addressed inorder to understand how this factor may influence generalizability in MH VEÕs.

The above cited investigations represent essential Òfirst-stepsÓ in determining whether VE-based assessment and treatment can foster generalization and transfer to other settings,particularly the real world! Generalization concerns have been fundamental in the evaluationof the effectiveness and value of MH approaches. This makes it essential that intuitive


expectations of positive VE results in this area be, in fact, supported with quality research.This will be vital in order for a VE approach to be taken seriously in the MH field.

9 . How should VE studies be designed and how will the data be analyzed?

A discussion of the methodological concerns and data analysis issues relating to VEÕs formental health applications could easily consume a full chapter in this volume! We will onlybriefly mention some of the general issues for this section. Much of the VE literature consistsof solid research designs using sophisticated statistical analyses. However, some of the initialwork with MH VEÕs is limited by a number of factors including, inadequate control groups,inconsistent reporting of statistics, and what appears to be a lack of a comprehensive long-term plan to address important issues. This is not meant to slight the innovative work ofscientists and clinicians that have begun the difficult work of exploring the practicalapplications of this emerging technology. Often with any new area of study, initial effortsconsist of mainly exploratory pilot projects designed to both, determine potential value andserve as a springboard for future funding opportunities that will provide support for moreserious in-depth investigation. The current status of research on MH VEÕs reflects this earlystage of development. However, the field is at a turning point where much of the initial effortsthat hint at the potential of this technology need to be explored and developed further. Thiswill require an awareness of the important issues and knowledge that has been uncovered thusfar, and then building upon this exploratory foundation.

Issues that need exploration were discussed earlier in this chapter and it is our belief thatmany of the questions cited should be consistently addressed in future studies. For example,it is recommended that future MH VE studies include some recording and reporting of sideeffects. This can, at a minimum, be attempted by using variously available questionnaires[93,94]. The same recommendation can be made for the estimation of presence factors via theuse of available rating scales [56]. Information regarding both side effects and presence,acquired with these basic tools, could provide the field with useful information that could aidin our understanding of the strengths and limitations of a VE approach for certain populationsand for specific targets. Another area that needs in-depth exploration involves the issue ofgeneralization. This issue requires considerable forethought when developing an experimentaldesign for any type of assessment and treatment study, and is no less important in the studyof VE approaches. There is a fair number of good transfer studies that are coming out of theHuman Factors literature on VEÕs, and these need to be carefully examined for the insight andtools that they provide, in order to construct better designs for specific MH applications.

Many issues related to the collection, management, and analysis of VE data remain to besolved. One problem concerns the development of VE systems without attention to theunderlying psychometric criteria. For example, while VE systems solely designed fortreatment applications have been successfully developed, certain applications may bepremature if it has yet to be demonstrated that the focus of treatment is a construct that isreliably and validly addressed by the given application. In these cases it may be necessary todevelop reliable and valid VE assessment techniques which allow for an analysis of thepsychometric properties of the application, and then attempt to develop the treatment focus ofthe system. By proceeding directly to the development of treatment applications there is thepossible risk that even successful applications will be developed where there is an inability toidentify the actual reasons for the obtained outcomes. While VEÕs will allow for thedevelopment of applications not possible prior to this technology, if we fail to establish itsvalidity for addressing psychological domains utilizing existing, validated instruments, wecould potentially be accused of bad science and short-sightedness. Also, much work alsoremains to be done in understanding the demand characteristics of VE exposure. While we arewell aware of the complexity of demands on subject performance associated withexperimental and clinical settings, the sociobehavioral effects of placing individuals in VEÕsneeds to be explored.

The analysis of VE generated data can also be problematic. Every event in a virtual worldcan be recorded and quantified, and every behavioral response of the user can be placed inthis digital context. The availability of such comprehensive and discrete data is one of the


most intriguing aspects of VEÕs. However, it poses the possibility of Òdrowning in oneÕsdata.Ó The data gathered in our Mental Rotation VE project (see Section 5) highlights thepossibilities, and difficulties, in data management and analysis. We are adapting a strategy ofstarting with a simplified data collection scheme while we are conducting feasibility studies,with a plan of increasing sophistication. Data we are recording on each problem are the visualquadrant in which both the stimuli and target are presented and the degree of rotation neededto accurately superimpose the stimuli on the target. The basic response parameter we areinitially recording is time to complete each trial. However, responses can also be coded interms of acceleration, velocity and direction--on a near continuous basis. We anticipate thatthe analysis of these parameters may provide insight into the userÕs problem solving strategy(i.e., trial and error approach versus more systematic tactics). Effective use of VEÕs for MHapplications will require a unique combination of existing data management and analysissystems. Novel analytic solutions based on the research objectives of the particular applicationwill need to be developed in order to allow for meaningful psychometric analysis. Whilestandards already exist for established methodologies, exploratory data analysis strategies willbe required in order to derive meaningful information from the massive amount of potentialdata available from virtual testing and training environments.

This brief sampling of methodological and statistical issues suggests some very basicconsiderations for the development and application of MH VEÕs. This direction in virtualtechnology is at the very beginning stages of development in terms of our understanding onhow to scientifically maximize the potential usefulness of VEÕs for MH applications. As alarger body of VE-related literature develops, we will be in a better position to consider thestandards that should be applied to research-based and clinically-oriented MH applications.This is a natural progression in the development of any new area of science and a good deal ofexciting, challenging, and potentially beneficial work remains to be done!

References

[1] L.F. Hodges, R. Kooper, B.O. Rothbaum, D. Opdyke, J.J. de Graaff, J.S. Williford, & M.M. North,Virtual environments for treating the fear of heights. Computer Innovative Technology for ComputerProfessionals, 28:7 (1995) 27-34.

[2] L.F. Hodges, B.O. Rothbaum,B.A. Watson, G.D. Kessler, & D. Opdyke, Virtually conquering fearof flying. IEEE Computer Graphics & Applications, 16:6 (1996) 42-49.

[3] A.S. Carlin, H.G. Hoffman, & S. Weghorst, Virtual reality and tactile augmentation in the treatmentof spider phobia: a case report. Behavioral Research Therapy, 35:2 (1997) 153-158.

[4] M.M. North, S.M. North, & J.R. Coble, Virtual environments psychotherapy: A case study of fearof flying disorder. Presence: Teleoperators and Virtual Environments, 5:4 (1996) 1-5.

[5] M.M. North, S.M. North, & J.R. Coble, Virtual reality therapy. IPI Press, Colorado Springs, CO.,1996.

[6] B.O. Rothbaum, L.F. Hodges, R. Kooper, D. Opdyke, J.S. Williford, & M. North, Effectiveness ofcomputer-generated (virtual reality) graded exposure in the treatment of acrophobia. American Journalof Psychiatry, 152: (1995) 626-628.

[7] B.O. Rothbaum, L.F. Hodges, R. Kooper, Virtual reality exposure therapy. Journal of.Psychotherapy Practice and Research, 6:3 (1997) 291-296.

[8] H.G. Hoffman, VR for burn pain control during wound care. Paper presented at The 6th AnnualConference on Medicine Meets Virtual Reality. San Diego, CA., January 31, 1997.

[9] H. Oyama, Clinical applications of virtual reality for palliative medicine. CyberPsychology and Behavior, 1:1(1998) 53-58.

[10] G. Riva, Virtual reality in psychological assessment: The Body Image Virtual Reality Scale.CyberPsychology and Behavior, 1:1 (1998) 37-44.

[11] D.P. Inman, K. Loge, & J. Leavens, VR education and rehabilitation. Communications of the ACM, 40:8(1997) 53-58.

[12] N. Foreman, P. Wilson, & D. Stanton, VR and spatial awareness in disabled children.Communications of the ACM, 40:8 (1997) 76-77.

[13] J.J. Cromby, P.J. Standen, J. Newman & H. Tasker, Successful transfer to the real world of skillspractised in a virtual environment by students with severe learning difficulties. In: P. Sharkey, (ed.)


Proceedings of the European Conference on Disability, Virtual Reality and Associated Technology.(1996) 103-107.

[14] D.J. Brown & D.S. Stewart, An emergent methodology for the design, development andimplementation of virtual learning environments. In: P. Sharkey, (ed.) Proceedings of the EuropeanConference on Disability, Virtual Reality and Associated Technology. (1996) 75-84.

[15] D. Strickland, A virtual reality application with autistic children. Presence: Teleoperators and VirtualEnvironments, 5:3 (1996) 319-329.

[16] E.A. Attree, B.M. Brooks, F.D. Rose, T. K. Andrews, A.G. Leadbetter & B.R. Clifford, Memoryprocesses and virtual environments: I can't remember what was there, but I can remember how I gotthere. Implications for people with disabilities. In: P. Sharkey, (ed.) Proceedings of the EuropeanConference on Disability, Virtual Reality and Associated Technology. (1996) 117-121.

[17] J.P. Wann, S.K. Rushton, M. Smyth, & D. Jones, Rehabilitative environments for attentionmovement disorders. Communications of the ACM, 40:8 (1997) 49-52.

[18] A. A. Rizzo, J.G. Buckwalter, U. Neumann, C. Kesselman, M. Thiebaux, P. Larson, & A. vanRooyen, The virtual reality mental rotation spatial skills project. CyberPsychology and Behavior, 1:2(1998) 107-113.

[19] J. McComas, J. Pivik, M. Laflamme, Children's transfer of spatial learning from virtual reality toreal environments. CyberPsychology and Behavior, 1:2 (1998).

[20] L. Pugnetti, L. Mendozzi, E.A. Attree, E. Barbieri, B.M. Brooks, C.L. Cazzullo, A. Motta, & F.D.Rose. Probing memory and executive functions with virtual reality. Past and present studies.CyberPsychology and Behavior, 1:2 (1998).

[21] S. Aukstakalnis & D. Blatner, Silicon Mirage: The Art and Science of Virtual Reality. PeachpitPress: Berkeley CA. 1992.

[22] A.A. Rizzo, & J.G. Buckwalter, Virtual reality and cognitive assessment and rehabilitation: The stateof the art. In: G. Riva ed., Psycho-neuro-physiological Assessment and Rehabilitation in VirtualEnvironments: Cognitive, Clinical, and Human Factors in Advanced Human Computer Interactions,IOS Press: Amsterdam, (1997) 123-145.

[23] K. Glantz, N.I. Durlach, R.C. Barnett, & W.A. Aviles, Virtual reality (VR) and psychotherapy:Opportunities and challenges. Presence: Teleoperators and Virtual Environments, 6:1 (1997) 87-105.

[24] B. K. Wiederhold, & M.D. Wiederhold, A review of virtual reality as a psychotherapeutic tool.CyberPsychology and Behavior, 1:1 (1998) 45-52.

[25] K.M. Stanney, G. Salvendy, et al., Aftereffects and sense of presence in virtual environments:Formulation of a research and development agenda. Report sponsored by the Life Sciences Divisionat NASA Headquarters. International Journal of Human-Computer Interaction, 10:2 (1998) 135-187.

[26] J.P. Wann, Virtual reality environments for rehabilitation of perceptual-motor disorders followingstroke. In: P. Sharkey, (ed.) Proceedings of the European Conference on Disability, Virtual Realityand Associated Technology. (1996) 233-238.

[27] M.F. Folstein, S.E. Folstein, & P.R. McHugh, ÒMini Mental StateÓ: A practical method for gradingthe cognitive state of outpatients for the clinician. Journal of Psychiatric Research, 12 (1975) 189-198.

[28] F.D. Rose, Virtual reality in rehabilitation following traumatic brain injury. In: P. Sharkey, (ed.)Proceedings of the European Conference on Disability, Virtual Reality and Associated Technology.(1996) 5-12.

[29] A. A. Rizzo, J.G. Buckwalter, U. Neumann, C. Kesselman, & M. Thiebaux, Basic issues in theapplication of virtual reality for the assessment and rehabilitation of cognitive impairments andfunctional disabilities. CyberPsychology and Behavior, 1:1 (1998) 59-78.

[30] W.O. Eaton, & L.R. Enns, Sex differences in human motor activity level. Psychological Bulletin,100 (1986) 19-28.

[31] J.S. Hyde, Gender differences in aggression. In: J.S. Hyde & M.C. Linn (Eds.) The psychology ofgender. Johns Hopkins University Press: Baltimore, MD. 1986 51-66.

[32] J.S. Wolpe, Psychotherapy by reciprocal inhibition. Stanford University Press: Stanford CA. 1958.[33] T.G. Stampfl, & D.J. Levis, Essentials of implosive therapy: A learning theory-based psychodynamic

behavioral therapy. Journal of Abnormal Behavior, 72 (1967) 496-503.[34] W. Yule, B. Sacks, & L. Hersov, Successful flooding treatment of a noise phobia in an eleven-year-

old. Journal of Behavior Therapy and Experimental Psychiatry, 5 (1974) 209-211.[35] E. Richter-Heinrich, & N.E. Miller, Biofeedback-basic problems and clinical applications. Elsevier:

North-Holland 1982.


[36] M.M. North, S.M. North, & J.R. Coble, Virtual reality therapy: An effective treatment for psychologicaldisorders. In: Riva G. ed. Psycho-neuro-physiological Assessment and Rehabilitation in VirtualEnvironments: Cognitive, Clinical, and Human Factors in Advanced Human Computer Interactions,IOS Press: Amsterdam, (1997) 59-70.

[37] G. Holden, D. Bearison, D. Rode, M. Fishman, & G. Rosenberg, Virtual reality and hospitalizedchildren: A pilot study with aggregation of the results of replicated single system designs via meta-analysis. Retrieved July 6, 1998 from the World Wide Web:http://www.starbright.org/projects/vrpilot.html.

[38] G.M. Escamilla, Y. Falkinstein, C.Y. Chang, D.I. Schneider, & L.K. Zeltzer, Reducing acute painthrough computer generated distraction in children. Journal of Investigative Medicine, 45:1 (1997)86A.

[39] J.J. Annesi, & J. Mazas, Effects of virtual reality-enhanced exercise equipment on adherence andexercise-induced feeling states. Perceptual and Motor Skills, 85 (1997) 835-844.

[40] M.M. Sohlberg, & C.A. Mateer, Effectiveness of an attention training program. Journal of Clinicaland Experimental Neuropsychology 9 (1987) 117-130.

[41] J.R. Crawford, Introduction to the assessment of attention and executive functioning.Neuropsychological Rehabilitation, 8:3 (1998) 209-211.

[42] L. Pugnetti, L. Mendozzi, A. Motta, A. Cattaneo, E. Barbieri, & S. Brancotti, Evaluation andretraining of adults' cognitive impairments: Which role for virtual reality technology? Computers inBiology and Medicine, 25:2 (1995) 213-227.

[43] L. Mendozzi, A. Motta, E. Barbieri, D. Alpini, & L. Pugnetti, The application of virtual reality todocument coping deficits after a stroke: Report of a case. CyberPsychology and Behavior, 1:1 (1998)79-91.

[44] C.T. Tart, Multiple personality, altered states and virtual reality: The world simulation processapproach. Dissociation 3:4 (1990) 222-233.

[45] G.L. Paul, Outcome of systematic desensitization II: Controlled investigations of individualtreatment, technique variations and current status. In: Franks CM, ed. Behavior therapy: Appraisal andstatus. McGraw-Hill: New York 1969.

[46] G.F. Cartwright, Virtual or real? The mind in cyberspace. The Futurist, Mar-Apr (1994): 22-26.[47] L.J. Whalley, Ethical issues in the application of virtual reality to medicine. Computers in Biology

and Medicine, 25:2 (1995) 107-114.[48] R.W. Bloom, Psychiatric therapeutic applications of virtual reality technology (VRT): Research

prospectus and phenomenological critique. In K.S. Morgan, H.M. Hoffman, D. Stredney, & S.Weghorst, Eds. Medicine Meets Virtual Reality: Global Healthcare Grid. IOS Press: Amsterdam,1997, 11-16.

[49] H.S. Muscott, & T. Gifford, Virtual reality and social skills training for students with behavioraldisorders: Applications, challenges and promising practices. Education and Treatment of Children, 17:3(1994)417-34.

[50] M. Rizzo, S. Reinach, D. McGehee, & J. Dawson, Simulated car crashes and crash predictors indrivers with Alzheimer's disease. Archives of Neurology, 54 (1997) 545-551.

[51] D.L. Jaffe, Use of virtual reality techniques to train elderly people to step over obstacles. Paperpresented at the Technology and Persons with Disabilities Conference, Los Angeles, CA. March 19,1998.

[52] N. Butters, D.P. Salmon, W. Heindel, & E. Granholm, Episodic, semantic, and procedural memory:Some comparisons of Alzheimer and Huntington disease patients. In: R.D. Terry, ed. Aging and theBrain. Raven Press: New York (1988).

[53] M.J. Singer, & B.G. Witmer, Presence: Where are we now? In M. Smith, G. Salvendy, & R.Koubek, Eds. Design of computing systems: Social and ergonomic considerations. Elsevier SciencePublishers: Amsterdam, Netherlands, (1997) 885-888.

[54] K.M. Stanney, R. Mourant, R.S. Kennedy, Human factors issues in virtual environments: A reviewof the literature. Presence: Teleoperators and Virtual Environments. In Press.

[55] J. Wann, & M. Mon-Williams, What does virtual reality NEED? Human factors issues in the design ofthree dimensional computer environments. International Journal of Human-Computer Studies, 44 (1996)829-847.

[56] B.G. Witmer, & M.J. Singer, Measuring presence in virtual environments: A Presence Questionnaire.Presence: Teleoperators and Virtual Environments, 7:3 (1998) 225-240.


[57] B.N.I. Durlach, & A.S. Mavor, Virtual Reality: Scientific and technological challenges. NationalAcademy Press: Washington, DC (1995).

[58] J. Psotka, S.A. Davison, & S.A. Lewis, Exploring immersion in virtual space. Virtual RealitySystems 1:2 (1993) 70-92.

[59] M. Slater, & M. Usoh, The influence of a virtual body on presence in immersive virtualenvironments. Virtual Reality '93: Proceedings of the Third Annual Conference on Virtual Reality.Meckler Ltd.: Westport CT, (1993) 34-42.

[60] M. Slater, M. Usoh, & A. Steed, Depth of presence in virtual environments. Presence: Teleoperatorsand Virtual Environments, 3:2 (1994) 130-144.

[61] D.W. Schloerb, A quantitative measure of telepresence. Presence: Teleoperators and VirtualEnvironments, 4:1 (1995) 64-80.

[62] R.B. Welch, The presence of aftereffects. In G. Salvendy, M. Smith, and R. Koubek, Eds., Design ofcomputing systems: Cognitive considerations (pp. 273-276). Elsevier Science Publishers:Amsterdam, Netherlands, (1997) 273-276.

[63] W. Barfield, & S. Weghorst, The sense of presence within virtual environments: A conceptualframework. In G. Salvendy and M. Smith, Eds., Human-Computer Interaction: Software andHardware Interfaces Elsevier Science Publishers: Amsterdam, Netherlands, (1993) 699-704.

[64] V.J. Cohn, P. DiZio, & J.R. Lacknerr, Reaching movements during illusory self-rotation showcompensation for expected Coriolis forces. Society for Neuroscience Abstracts, 22:1 (1996) 654.

[65] V.J. Cohn, P. DiZio, & J.R. Lackner, Reaching during virtual rotation II: Context specificcompensations for apparent self-displacement reaching during virtual rotation. Manuscript submittedfor publication (1997).

[66] S.R. Ellis, N.S. Dorighi, B.M. Menges, B.D. Adelstein, & R.H. Jacoby, In search of equivalenceclasses in subjective scales of reality. In M. Smith, G. Salvendy, and R. Koubek, Eds., Design ofcomputing systems: Social and ergonomic considerations. Elsevier Science Publishers: Amsterdam,Netherlands, (1997) 873-876.

[67] R. Pausch, D. Proffitt, & G. Williams, Quantifying immersion in virtual reality. Computer GraphicsProceedings, Annual Conference Series/ ACM SIGGRAPH, ACM SIGGRAPH: Los Angeles, CA(1997) 13-18.

[68] M.J. Singer, J. Ehrlich, S. Cinq-Mars, & J. Papin, Task performance in virtual environments:Stereoscopic vs. monoscopic displays and head-coupling (Technical Report 1034), U.S. ArmyResearch Institute for the Behavioral and Social Science: Alexandria, VA. (1995).

[69] R.B. Welch, T.T. Blackmon, A. Liu, B.A. Mellers, & L.W. Stark, The effects of pictorial realism,delay of visual feedback, and observer interactivity on the subjective sense of presence. Presence:Teleoperators and Virtual Environments, 5:3 (1996) 263-273.

[70] A.A. Rizzo, J.G. Buckwalter, & U. Neumann, The virtual reality attention process assessment andtraining project. Unpublished manuscript.

[71] A. Rovetta, F. Lorini, & M.R. Canina, Virtual reality in the assessment of neuromotor diseases:Measurement of time response in real and virtual environments. In: G. Riva ed., Psycho-neuro-physiological Assessment and Rehabilitation in Virtual Environments: Cognitive, Clinical, andHuman Factors in Advanced Human Computer Interactions, IOS Press: Amsterdam, (1997) 165-184.

[72] M. Steffin, Virtual reality therapy of multiple sclerosis and spinal cord injury: Design considerationsfor a haptic-visual interface. In: G. Riva ed., Psycho-neuro-physiological Assessment andRehabilitation in Virtual Environments: Cognitive, Clinical, and Human Factors in Advanced HumanComputer Interactions, IOS Press: Amsterdam, (1997) 185-208.

[73] T. Kuhlen, K.F. Kraiss, A. Szymanski, C. Dohle, H. Hefter, & H.J. Freund, Virtual holography indiagnosis and therapy of sensorimotor disturbance. In: H. Murphy, ed. Proceedings of the 3rdInternational Conference on Virtual Reality and Persons with Disabilities. CSUN: Northridge, CA.1995.

[74] J. Psotka, Immersive training systems: Virtual reality and education and training. InstructionalScience, 23 (1995) 405-431.

[75] L. Pugnetti, L. Mendozzi, A. Motta, A. Cattaneo, E. Barbieri, A. Brancotti, & C.L. Cazzullo.Immersive VR for the retraining of acquired cognitive defects. Paper presented at the Medicine MeetsVirtual Reality 3 Conference. San Diego, CA.1995.

[76] T. Middleton, D. Boman, ÒSimon SaysÓ: Using speech to perform tasks in virtual environments. InMurphy ed. Proceedings of the 2nd Annual Conference on Virtual Reality and Persons withDisabilities. CSUN: Northridge, CA, (1994) 76-79.


[77] P. Peruch, .L. Vercher, & G.M. Gauthier, Acquisition of spatial knowledge through visualexploration of simulated environments. Ecological Psychology 7:1 (1995) 1-20.

[78] P. Wilson, Nearly There. Special Child 68 (1993) 28-30.[79] R.S. Kennedy, K.S. Berbaum, & J. Drexler, Methodological and measurement issues for

identification of engineering features contributing to virtual reality sickness. Paper presented at: Image7 Conference. Tucson, AZ.1994.

[80] J.T. Reason, Motion sickness: A special case of sensory rearrangement. Advancement in Science 26(1970) 386-393.

[81] R.S. Kennedy, K.M. Stanney, J.M. Ordy, & W.P.Dunlap, Virtual reality effects produced by head-mounted display (HMD) on human eye-hand coordination, postural equilibrium, and symptoms ofcybersickness. Society for Neuroscience Abstracts, 23 (1997) 772.

[82] B.D. Lawson, A.H. Rupert, F.E. Guedry, J.D. Grissett, & A.M. Mead, The human-machine interfacechallenges of using virtual environment (VE) displays aboard centrifuge devices. In M. Smith, G.Salvendy, and R. Koubek, Eds., Design of computing systems: Social and ergonomic considerations.Elsevier Science Publishers: Amsterdam, Netherlands (1997) 945-948.

[83] J.P. Rolland, F.A. Biocca, T. Barlow, & A. Kancherla, Quantification of adaptation to virtual-eyelocation in see-thru head-mounted displays. IEEE Virtual Reality Annual International SymposiumÔ95. IEEE Computer Society Press: Los Alamitos CA. (1995) 56-66.

[84] P. DiZio & J.R. Lackner, Spatial orientation, adaptation, and motion sickness in real and virtualenvironments. Presence: Teleoperators and Virtual Environments. 1 (1992) 323.

[85] R.S. Kennedy, & K.M. Stanney, Postural instability induced by virtual reality exposure:Development of certification protocol. International Journal of Human-Computer Interaction, 8:1(1996) 2547.

[86] K.M. Stanney, & R.S. Kennedy, The psychometrics of cybersickness. Communications of the ACM40:8 (1997) 67-68.

[87] L.J. Hettinger, Visually induced motion sickness in virtual environments. Presence: Teleoperators andVirtual Environments. 1 (1992) 306-307.

[88] R.S. Kennedy, N.E. Lane, M.G. Lilienthal, K.S. Berbaum & L.J. Hettinger, Profile analysis ofsimulator sickness symptoms: Application to virtual environment systems. Presence: Teleoperatorsand Virtual Environments. 1 (1992) 295-301.

[89] E. Regan & K.R. Price, The frequency of occurrence and severity of side-effects of immersion virtualreality. Aviation, Space, & Environmental Medicine. 65 (1994) 527-530.

[90] G. Kolasinski, Simulator sickness in virtual environments. (Tech Report 1027). Orlando: UnitedStates Army Research Institute for the Behavioral and Social Sciences. (1995).

[91] K.M. Stanney & P. Hash, Locus of user-initiated control in virtual environments: Influences oncybersickness. Presence: Teleoperators and Virtual Environments. (in press).

[92] R.B. Loftin & P.J. Kenny, Training the Hubble Space Telescope Flight Team. IEEE ComputerGraphics and Applications. Sept. (1995) 31-37.

[93] R.S. Kennedy, N.E. Lane, K.S. Berbaum, & M.G. Lilienthal, Simulator sickness questionnaire: Anenhanced method for quantifying simulator sickness. International Journal of Aviation Psychology,3:3 (1993) 203-220.

[94] P. Dizio, & J.R. Lackner, J.R, Circumventing side effects of immersive virtual environments. In M.Smith, G. Salvendy, and R. Koubek, Eds. Design of computing systems: Social and ergonomicconsiderations. Elsevier Science Publishers: Amsterdam, Netherlands, (1997) 893-896.

[95] J.P. Wann, S.K. Rushton, & M. Mon-Williams, Natural problems for stereoscopic depth perceptionin virtual environments. Vision Research, 19 (1995) 2731-2736.

[96] T.F. Stokes & D.M. Baer, An implicit technology of generalization. Journal of Applied BehaviorAnalysis. 10 (1977) 349-367.

[97] R. Lamson, & M. Meisner, The effects of virtual reality immersion in the treatment of anxiety, panicand phobia of heights. In Murphy ed. Proceedings of the 2nd Annual Conference on Virtual Realityand Persons with Disabilities. CSUN: Northridge, CA. (1994) 63-68.

[98] R. Johnston, Is it live or is it memorized? Virtual Reality Special Report. 2:3 (1995) 53-56.[99] J.J. Kozak, P.A. Hancock, E.J. Arthur & S.T. Chrysler, Transfer of training from virtual reality.

Ergonomics. 36:7 (1993) 777-784.[100] J.W. Regian,W.L. Shebilske & J.M. Monk, Virtual reality: An instructional medium for visual-

spatial tasks. Journal of Communication. 42 (1992) 136-149.


[101] J.W. Regian,W.L. Shebilske & J.M. Monk, VR as a training tool: Transfer effects. Unpublishedmanuscript. Armstrong Laboratory, Brooks Air Force Base, Texas.

[102] S. Goldberg, Training dismounted soldiers in a distributed interactive virtual environment. U.S. ArmyResearch Institute Newsletter. 14:April (1994) 9-12.

[103] D. Johnson, Virtual environments in Army aviation training. Proceedings of the 8th Annual TrainingTechnology Technical Group Meeting, Mountain View, CA, (1994) 47-63.

[104] A. Paton, Education in the virtual factory. Paper presented at The Spring VRWORLD Ô95Conference, San Jose, CA, (1995).

[105] W. Gordon, Methodological considerations in cognitive remediation. In: M. Meier, A. Benton & L.Diller, eds. Neuropsychological Rehabilitation. Guilford Press: New York (1987).

[106] D. Waller, E. Hunt, & D. Knapp, The transfer of spatial knowledge in virtual environment training.Presence: Teleoperators and Virtual Environments, 7:2 (1998) 129-143.

BASIC ISSUES IN THE USE OF VIRTUAL ENVIRONMENTS FOR MENTAL HEALTH APPLICATIONS

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