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CyberPsychology & Behavior Volume 1, Number 2, 1998 Mary Ann Liebert, Inc. Virtual Reality: A New Tool for Interdisciplinary Psychology Research HUNTER HOFFMAN, Ph.D. ABSTRACT . Virtual reality (VR) has the potential to become a powerful scientific research tool for psy¬ chologists. VR serves as a bridge between different disciplines of psychology. Findings in one area are often easily applied to others, encouraging researchers who use VR to collabo¬ rate with experts from various fields. To support these claims, I will describe VR research on the following psychological topics, spanning several levels of analysis and several disciplines of psychology. In the process, I will describe how these various levels of analysis can inform and build upon each other. 1. Perception: Tactile augmentation, a technique for giving VR users the sensation of "touching" virtual objects with their real hands. 2. Memory and Cog¬ nition: Virtual-Reality monitoring, the decision process by which people try to distinguish memories of real events from memories of virtual events. 3. Clinical Psychology: VR expo¬ sure therapy for treatment of spider phobia: A case study. 4. Medical applications of VR: Use of VR to distract adolescent burn victims from burn pain: A case study. INTRODUCTION Psychology research is becoming increas¬ ingly multi-disciplinary. Virtual reality (VR) has the potential to become a powerful scientific research tool for psychologists. VR can serve as a bridge between different disci¬ plines of psychology. Findings in one area are often easily applied to others, encouraging re¬ searchers who use VR to collaborate with ex¬ perts from various fields. To support these claims, this article will describe VR research on Perception, Memory and Cognition, and appli¬ cations of VR to treating clinical disorders and medical problems, and will describe how these various levels of analysis can inform and build upon each other. These research topics span several levels of analysis and several disci¬ plines of Psychology. Human Interface Technology Lab, and Dept. of Psychol¬ ogy, University of Washington, Seattle, WA 98195. PERCEPTION Hoffman et al.1 (1996) found that physically touching a virtual object (mixing real objects and VR) improves the quality of the virtual ex¬ perience. For some objects, subjects saw a vir¬ tual object (e.g., an image of a ball) and touched its real counterpart (a rubber ball). Compared to visual VR only, converging evidence from both visual and tactile senses increased the il¬ lusion of "being in a place" when experiencing the virtual environment or VE (Figures 1-3). In Hoffman,2 subjects in a "cyberheft" con¬ dition were able to touch and pick up a virtual plate that had solidity and weight. Compared to another group who picked up a weightless, non-solid virtual plate, subjects in the cyberheft condition predicted that other unexplored vir¬ tual objects, walls and countertops would have higher solidity, weight, and would obey grav¬ ity (Figure 4). Adaptation to a virtual environ¬ ment involves making inferences about what rules from the real world apply in the virtual 195

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CyberPsychology & BehaviorVolume 1, Number 2, 1998Mary Ann Liebert, Inc.

Virtual Reality: A New Tool for InterdisciplinaryPsychology Research

HUNTER HOFFMAN, Ph.D.

ABSTRACT.

Virtual reality (VR) has the potential to become a powerful scientific research tool for psy¬chologists. VR serves as a bridge between different disciplines of psychology. Findings inone area are often easily applied to others, encouraging researchers who use VR to collabo¬rate with experts from various fields. To support these claims, I will describe VR research on

the following psychological topics, spanning several levels of analysis and several disciplinesof psychology. In the process, I will describe how these various levels of analysis can informand build upon each other. 1. Perception: Tactile augmentation, a technique for giving VRusers the sensation of "touching" virtual objects with their real hands. 2. Memory and Cog¬nition: Virtual-Reality monitoring, the decision process by which people try to distinguishmemories of real events from memories of virtual events. 3. Clinical Psychology: VR expo¬sure therapy for treatment of spider phobia: A case study. 4. Medical applications of VR: Useof VR to distract adolescent burn victims from burn pain: A case study.

INTRODUCTION

Psychology research is becoming increas¬ingly multi-disciplinary. Virtual reality

(VR) has the potential to become a powerfulscientific research tool for psychologists. VRcan serve as a bridge between different disci¬plines of psychology. Findings in one area are

often easily applied to others, encouraging re¬searchers who use VR to collaborate with ex¬

perts from various fields. To support theseclaims, this article will describe VR research on

Perception, Memory and Cognition, and appli¬cations of VR to treating clinical disorders andmedical problems, and will describe how thesevarious levels of analysis can inform and buildupon each other. These research topics spanseveral levels of analysis and several disci¬plines of Psychology.

Human Interface Technology Lab, and Dept. of Psychol¬ogy, University of Washington, Seattle, WA 98195.

PERCEPTION

Hoffman et al.1 (1996) found that physicallytouching a virtual object (mixing real objectsand VR) improves the quality of the virtual ex¬

perience. For some objects, subjects saw a vir¬tual object (e.g., an image of a ball) and touchedits real counterpart (a rubber ball). Comparedto visual VR only, converging evidence fromboth visual and tactile senses increased the il¬lusion of "being in a place" when experiencingthe virtual environment or VE (Figures 1-3).

In Hoffman,2 subjects in a "cyberheft" con¬

dition were able to touch and pick up a virtualplate that had solidity and weight. Comparedto another group who picked up a weightless,non-solid virtual plate, subjects in the cyberheftcondition predicted that other unexplored vir¬tual objects, walls and countertops would havehigher solidity, weight, and would obey grav¬ity (Figure 4). Adaptation to a virtual environ¬ment involves making inferences about whatrules from the real world apply in the virtual

195

196 HOFFMAN

Touch group No Touch group

Did VHbecomereality?

Was VR"seen" or"visited"?

FIG. 1. Tactile augmentation, a type of mixed reality.Subject holds a position tracked real plate he sees in VR.(Images by H. Hoffman, VRAIS '98; used with permis¬sion.)2

world. The perception literature on how thebrain unifies sensory input from touch andsight to create a single percept (e.g., Welch andWarren3) guided our use of real objects to en¬

hance the realism of virtual reality, a techniquecalled tactile augmentation. Tactile augmenta¬tion is a form of mixed reality, blurring the dis¬tinction between what is real and what is vir¬tual.

MEMORY AND COGNITION

The essence of immersive VR is the experi¬ence of "being there" in the computer-gener¬ated environment (presence). Users become en-

FIG. 3. Means and standard errors from Hoffman et al.,Exp. 1 (1997). Physically touching virtual objects en¬hanced VR users' sense of presence in the virtual envi¬ronment. (Images by H. Hoffman, VRAIS '98; used withpermission.)2

gaged in events in VR, experiences they re¬

member later. Memories for events that oc¬

curred in VR constitute a new source of mem¬

ories, different from the traditional memorysources (real world, imagined, or dreams). Mycolleagues and I4-5 are conducting research on

"virtual-reality monitoring," a twist on theJohnson-Raye reality monitoring paradigm.6 Inthe study phase of Hoffman7 I exposed peopleto various common objects (e.g., an orange).Some objects were seen in VR, others were seenin the real world (subjects lifted up their hel-

Predictions about the properties of KitchenWorld Touch No Touch(error bars = SE)

how howsolid solidwas virtualteapot? walls?

howsolidcounter-top?

howmuchteapotweigh

teapot Meansobey of Q1 to 5gravity?

FIG. 2. The plate seen by the subject in Figure 1 as seen

through one eye (Images by H. Hoffman, VRAIS '98; usedwith permission.)2

FIG. 4. Results of Hoffman.2 Cyberheft increased pre¬dictions about the laws of nature obeyed in Virtual Real¬ity.

VR AND INTERDISCIPLINARY PSYCHOLOGY RESEARCH 197

met to see). Seven days later, subjects returnedto take a memory source identification test.

They were shown the name of an object (e.g.,book) and had to decide whether they had seenit during the study phase in the real world, inthe virtual world, or if it was new (i.e., not inthe study phase). Later they filled out a Mem¬ory Characteristics Questionnaire designed tomeasure the phenomenological qualities asso¬

ciated with their memories. According to John¬son and colleagues6'8 people infer whether an

event was real or imagined based on qualitiesassociated with the memory at time of retrieval.Hoffman2 Exp. 1, explores whether people use

a similar decision process when deciding if a

memory was real or virtual. What qualities are

associated with memories of virtual events? Dothese qualities help people infer the virtualsource of the memories? In other words, howuseful is it to study virtual reality using theJohnson-Raye theoretical framework? In ex¬

periment 2 (in progress), for one group of sub¬jects, tactile augmentation is being used to addphysical properties (e.g., solidity and cyber¬heft) to the virtual objects. For example, sub¬jects in the see-and-touch group touch a real or¬

ange with their position-tracked real hand,while their virtual hand explores a virtual or¬

ange. For other objects, they will lift their hel¬mets and touch the real object while looking atthe real object. A second "see only" group willsee real and virtual objects, but will not toucheither. Based on Hoffman,2 I predict the group

that touches the virtual objects will find themmore realistic. If so, the qualities associatedwith the object in memory will likely be more

similar to qualities associated with a memoryfor a real object, increasing real/virtual mem¬

ory source confusions (VR monitoring errors)on the memory test 1 wk later.

Like other source monitoring tasks (e.g., Dy-wan and Jacoby9), VR monitoring may provevaluable for studying human memory (e.g.,age-related declines in memory performance),and for "cybercognition," the study of how hu¬mans think in immersive and non-immersivecomputer-simulated environments.

FIG. 5. Experimenter demonstrates VR exposure ther¬apy for spider phobia (photo copyrighted by Mary Levin,U.W., used with permission).

CLINICAL PSYCHOLOGY

A recent clinical case study explored the use

of immersive VR, including mixed reality tac¬tile feedback, for treating spider phobia. Wemodelled our treatment after pioneering VR ex¬

posure therapy treatments by Rothbaum,Hodges, and colleagues for fear of heights10and fear of flying.11 Prior to treatment, the sub¬ject displayed a number of serious symptoms,had been phobic for approximately 20 years,and was getting worse. Treatment (Figure 5) in¬volved exposure to a virtual brown Guyanabird-eating tarantula, and a virtual blackwidow (with cyberweb). VR successfullyevoked strong but carefully controlled emo¬

tional reactions from the subject. She graduallybecame less fearful of virtual spiders, and ableto progress to more frightening situations. Af¬ter 1 month of therapy, she was ready to phys¬ically "touch" a mixed reality spider. Tactilecues were achieved by allowing her to feel a

position-tracked real object (a furry toy spider)with her real hand, that corresponded to thevirtual spider she saw in the immersive VE (tac¬tile augmentation). Outcome after 3 months oftherapy (12 1-hr sessions) was excellent, as as¬

sessed by a number of ratings and measures, in¬cluding her behavior toward real spiders out¬side of therapy. She now kills real spiders shefinds in her house, is able to go camping in thewoods, and no longer shows the obsessive-com¬pulsive symptoms associated with her phobia.Her quality of life has improved dramatically(and 1 yr after therapy she is still doing great).

198 HOFFMAN

These findings converge with a growing bodyof evidence showing that VR can serve as an ef¬fective tool for clinical therapy. A second pa¬tient has since been treated successfully.

One of the reasons we used tactile augmen¬tation in SpiderWorld was to deliberately blurthe distinction between fact and fantasy (VR).This served two functions: (1) to increase thelevel of anxiety evoked by the virtual spiderand, thus, the effectiveness of desensitization,and (2) to increase generalization of trainingfrom the virtual world to the real world. It doesno good to cure a phobic's fear of virtual spi¬ders if they remain afraid of real spiders. Forour case study, treatment was very effective at

reducing the patient's fear of real spiders. Weplan to conduct controlled experiments ex¬

ploring the value of VR exposure therapy fortreating spider phobia. Whether tactile aug¬mentation enhances the value of VR exposuretherapy is an important research question.

In addition to blurring the distinction be¬tween fact and fantasy, tactile augmentationmay increase the amount of attention drawninto the virtual environment. VR can be con¬

sidered a sort of divided-attention task.12 Atsome level, subjects remain aware of the factthat they are standing in the laboratory wear¬

ing a helmet. But for many users, much of theirattention is drawn into the virtual environ¬ment, and subjects largely forget about theirreal bodies and their physical location. Thismay be especially true when the realism of thevirtual world is enhanced with tactile cues (us¬ing either tactile augmentation or computer-generated force feedback displays).

MEDICAL APPLICATIONS OF VR

The attention-grabbing nature of VR makesit attractive for certain medical applications.For example, severe burns require frequentdressing changes and painful wound cleansing(e.g., scraping off dead skin tissue from theburn). Both of these procedures can produceexcruciating pain, even in patients under heavymorphine medication. Part of this pain is dueto anxiety and other cognitive factors, and trag¬

ically, much of this suffering is unnecessary.13Patterson and colleagues14'15 have shown thatpsychological non-pharmacological interven¬tions such as hypnosis can reduce burn pain in¬tensity and unpleasantness. These burn painresearchers at U.W. Harborview Burn Center(Seattle, WA) have recently joined forces withVR researchers at the U.W. Human InterfaceTechnology Center (part of the WashingtonTechnology Center) to explore the possible use

of VR for burn pain reduction.The logic of why VR might help is as follows:

Human attention is a flexible, sharable pro¬cessing resource of limited availability.16'17 Ifpain requires attention, performing a task thatdraws heavily on the same attentional re¬

sources (i.e., a task sharing pain's attentionalresources), will reduce the amount of attentionavailable for processing pain, reducing the sub¬jective experience of pain and /or the amountof time patients spend thinking about the pain.

The Harborview/HITLab team18 success¬

fully used VR for burn pain distraction forMichael, an 11-year-old boy with gasolineburns on his hand and leg. The child rated hispain while in VR considerably lower than hisresting pain (Fig. 6). After removing his VR hel¬met, he realized with surprise that while in VRhe had temporarily "forgotten" that his burnedleg hurt. He was delighted that he couldn't see

his temporarily disfigured (real) leg while inVR. A second patient, Ryan, a 16-year-old withthird-degree burns on his face, neck, arm and

—100

£1(0too 80 e

Is60ç E

'cd ilQ-o

o 40-

Patient 1, Burn Pain Week Two(over about a 35 minute period)

NoVR NoVR NoVR

With VR With VR

FIG. 6. Hoffman et al. (1998). Preliminary data from thefirst use of VR for burn pain distraction (patient 1). (Im¬ages by H. Hoffman, VRAIS '98; used with permission.)2

VR AND INTERDISCIPLINARY PSYCHOLOGY RESEARCH 199

hand showed mixed results. Sometimes VRpain distraction significantly reduced his burnpain ratings, sometimes not. Encouragingly,during one session, he remarked with annoy¬ance that the questions about pain in VR were

not appropriate, because he was focussing on

the VR task not thinking about this pain. Fig¬uring out why some patients respond better toVR therapy than others is an important re¬

search topic. A third patient showed large re¬

ductions in pain ratings and amount of timespent thinking about pain during wound care

(Figure 7). Success with patient 3 is particularlyimportant because pain during wound care

reaches severe to excruciating levels for mostburn patients19 and is a target area for pain re¬

searchers.One limitation of case studies is that they

must be followed up with larger studies. Whileencouraging, the case reports described in thispaper are by their nature inconclusive, and re¬

quire converging evidence from carefully con¬

trolled experiments. In the future, we plan to

perform controlled experiments to determinewhether the magnitude of the patient's sense

of "presence" in the VE influences how effec¬tively VR distracts them from their pain. Ourfinding that Michael had high presence ratingsand Ryan had lower presence ratings is inter¬esting. Tactile augmentation will likely helpdraw the burn patient's minds even furtheraway from their pain-wracked bodies anddeeper into the virtual world during these rel-

FIG. 7. Burn patient 3 distracted from his pain duringwound care (Photo copyrighted by G. Carrougher, U.W.,used with permission.)

FIG. 8. The virtual pilot (image copyrighted by StigHollup, used with permission).

atively brief durations of intense pain duringwound care.

CONCLUSIONS

In summary, VR technology is a catalyst forinterdisciplinary research. Our experimentsand treatments drew upon several levels ofanalysis: perception, cognition, clinical, andperhaps social (changes in attitudes toward spi¬ders).

I am involved in some other projects at theHITLab: (1) exploring educational applicationsof VR in the public school system;20'21 and (2)exploring military applications of VR for theAir Force. There is a good deal of cross talk be¬tween these fields. For instance, efforts by theHITLab's Learning Center to create a networkedVR world for kids undergoing chemotherapyhelped inspire the development of a multi-par¬ticipant, distributed, networked military VRapplication, the Virtual Pilot22-24 (Figure 8).Thus, some core concepts transcend bound¬aries between entire disciplines of science.

ACKOWLEDGMENTS

Research was supported by a grant from theWashington State Firefighters Council, Na¬tional Institute of Heath grant GM42725-07, Sil¬icon Graphics, Paradigm Simulations, AFOSR,Logicon, and the HITLab consortium.

200 HOFFMAN

REFERENCES

1. Hoffman, H.G., Groen, J., Rousseau, S., Hollander, .,Winn, W. Wells, M., and Furness III, T. (1996). Tactileaugmentation: Enhancing presence in inclusive VR withtactile feedback from real objects. Paper presented at themeeting of the American Psychological Society, SanFrancisco.

2. Hoffman, H.G. (1998). Physically touching virtual ob¬jects using tactile augmentation enhances the realism ofvirtual environments. Proceedings of the JEEE VirtualReality Annual International Symposium '98, AtlantaGA., pp. 59-63. IEEE Computer Society, Los Alami-tos, CA.

3. Welch, R.B., and Warren, D.H. (1980). Immediate per¬ceptual response to intersensory discrepancy. Psycho¬logical Bulletin, 88, 638-667.

4. Hoffman, H.G., Hullfish, K.C., and Houston, S. (1995).Virtual-reality monitoring. Paper presented at the meet¬ing of the Virtual Reality Association InternationalSymposium (VRAIS), Research Triangle, NC.

5. Hullfish, K.C. (1996). Virtual Reality monitoring: Howreal is Virtual Reality! Unpublished Masters thesis.HITLab tech report #TH-96-2.

6. Johnson, M.K., and Raye, CL. (1981). Reality moni¬toring. Psychological Review, 88, 67-85.

7. Hoffman, H.G. (in preparation). Virtual Reality Moni¬toring: identifying the origins of real; and chimeric (mixedreality) memories.

8. Johnson, M.K., Hashtroudi, S., and Lindsay, D.S.(1993). Source monitoring. Psychological Bulletin, 114,3-28.

9. Dywan, J., and Jacoby, L. (1990). Effects of aging onsource monitoring: Differences in susceptibility tofalse fame. Psychology and Aging, 5, 379-387.

10. Rothbaum, B.O., Hodges, L.F., Kooper, R., Opdyke,D., Williford, J., and North, M.M. (1995). Effectivenessof virtual reality graded exposure in the treatment ofacrophobia. American Journal of Psychiatry, 152,626-628.

11. Rothbaum, B.O., Hodges, L.F., Watson, B.A., Kessler,G.D., and Opdyke, D. (1996). Virtual reality exposuretherapy in the treatment of fear of flying: A case re¬

port. Behavior Research Therapy, 34, 477-^81.12. Hoffman, H.E., Prothero, J., Wells, M., and Groen, J.

(in press). Virtual Chess: The role of meaning in thesensation of presence. International Journal of Human-Computer Interaction.

13. Melzack, R. (1990). The tragedy of needless pain. Sci¬entific American, 262, 27-33.

14. Patterson, D.R. (1995). Non-opioid-based approachesto burn pain. / Burn Care Rehabil 16, 372-376.

15. Patterson, D.R., Everett, J.J., Burns, G.L., and Marvin,

J.A. (1992). Hypnosis for the treatment of burn pain./ Consult Clin Psychol. 60, 713-717.

16. Kahneman, D. (1973). Attention and effort. Engle-wood Cliffs, NJ: Prentice-Hall.

17. Navon, D., and Gopher, D. (1979). On the economyof the human processing systems. Psychological Re¬view, 86, 254-255.

18. Hoffman, H.G., and Doctor, J.N., Patterson, D.R., Car-rougher, G.C., Taylor, W., Weghorst, S., and Furness,T. III. (1998). VRfor burn pain control during wound care.

Paper presented at Medicine Meets VR 6, San Diego,CA.

19. Perry, S., Heidrich, G., and Ramos, E. (1981). Assess¬ment of pain by burn patients. / Burn Care Rehabil 2,322-327.

20. Winn, W., Hoffman, H., and Osberg, K. (in press).Semiotics and the design of objects, actions and in¬teractions in virtual environments. Journal of Struc¬tural Learning.

21. Winn, W., Hoffman, H., Hollander, ., Osberg, K.,and Rose, H. (1997). The effect of student construction ofvirtual environments on the performance of high- and low-ability students. Presented at the Annual Meeting ofthe American Educational Research Association,Chicago, March 1997.

22. Wells, M.J., Baldis, S., and Hoffman, H.G. (1996). TheVirtual Pilot. Presentation at the Colloquium on Multi-Crew Performance in Complex Military Systems, heldat the 30th Annual Meeting of the Human Factors andErgonomics Society in Philadelphia, September 2-6.

23. Wells, M.J., and Hoffman, H.G. (1997). Task Allocationbetween real and virtual pilots: Putting real intelligenceinto a virtual cockpit. Paper presented at the 2nd An¬nual Symposium on Situational Awareness in the Tac¬tical Air Environment. Naval Air Warfare Center,Patuxent River, MD.

24. Wells, M.J., Hoffman, H.G., Smith, D., and Mitchell,T. (1998). Putting a virtual pilot on the crew roster. Pa¬per to be presented at the NATO human factors &medicine panel on collaborative crew performance incomplex operational systems, April 20-24, 1998, Ed¬inburgh, U.K.

Address reprint requests to:Hunter Hoffman, Ph.D.

Human Interface Technology LabUniversity of Washington

Seattle, WA 98195-2142

E-mail: [email protected]: www.httl.washington.edu/people/hunter