Future Directions: How Virtual Reality Can Further

CYBERPSYCHOLOGY, BEHAVIOR, AND SOCIAL NETWORKING Volume X, Number X, 2015 ª Mary Ann Liebert, Inc. DOI: 10.1089/cyber.2015.0412

ORIGINAL ARTICLE

Future Directions: How Virtual Reality Can Further Improve the Assessment and Treatment of Eating Disorders and Obesity Jose´ Gutie´rrez-Maldonado, PhD,1 Brenda K. Wiederhold, PhD, MBA, BCIA,2,3 and Giuseppe Riva, PhD 4,5

Abstract

Transdisciplinary efforts for further elucidating the etiology of eating and weight disorders and improving the effectiveness of the available evidence-based interventions are imperative at this time. Recent studies indicate that computer-generated graphic environments—virtual reality (VR)—can integrate and extend existing treatments for eating and weight disorders (EWDs). Future possibilities for VR to improve actual approaches include its use for altering in real time the experience of the body (embodiment) and as a cue exposure tool for reducing food craving.

coming years: attempts to modify the experience of the body through the phenomenon of embodiment, and cue exposure therapy (CET). Body image modification techniques focus on the experience of the body, while cue exposure, based on the psychology of learning, focuses on response. Just as important as these scientific foundations are the new technological innovations in the design of instruments for conducting virtual simulations, which are helping to produce highly immersive devices that are inexpensive and easy to use.

Introduction

T

he first studies of the application of virtual reality (VR) to eating and weight disorders (EWDs) were carried out by Riva under the aegis of VREPAR, a European project designed to develop virtual environments for the study, evaluation, and treatment of body image disorders.1,2 Subsequently, Perpinã´ et al.3,4 also developed programs for the evaluation and treatment of disorders of this kind. In the area of eating disorders, a feature of VR that has received considerable attention is its ability to trigger emotional reactions in patients.5,6 Comparing virtual stimuli with the corresponding real stimuli and photographs, Gorini et al.7 found that virtual food was as effective as real food, and more effective than photographs of food, in triggering psychological and physiological responses in patients with eating disorders. This finding was not related to the patients’ specific diagnosis, since patients with anorexia nervosa (AN) or bulimia nervosa (BN) presented similar responses. These studies thus demonstrate the validity of VR for use as an exposure technique in place of real stimuli in treating patients with eating disorders. VR offers high ecological validity given its ability to locate specific stimuli in the context of simulations of real situations, and also high internal validity given its ability to control the parameters of exposure. Research into the applications of VR in EWDs is still expanding, and in combination with findings from other areas, it is likely to boost the growth of two types of intervention in the

Research and Intervention at the Level of Perception: Embodiment

Although various longitudinal studies highlight the unhealthy weight-control behaviors used to counter body dissatisfaction as the common antecedents of eating and weight disorders, transdisciplinary efforts for further elucidating this mechanism and improving the effectiveness of the available evidence-based interventions are imperative at this time. To achieve a better explanation of these mechanisms, Riva proposed the ‘‘Allocentric Lock Hypothesis.’’8–15 The key hypothesis of this framework is that both obesity (OB) and eating disorders (EDs) (i.e., AN and BN) are the outcome of a primary disturbance in the way the body is ‘‘experienced’’ and ‘‘remembered.’’ Differently from other physical objects, our body is experienced both as object (third person)—we perceive our body as a physical object in the external world—and as

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Department of Personality, Assessment, and Psychological Treatments, University of Barcelona, Barcelona, Spain. Virtual Reality Medical Institute, Brussels, Belgium. 3 Virtual Reality Medical Center, San Diego, California. 4 Department of Psychology, Universita` Cattolica del Sacro Cuore, Milan, Italy. 5 Applied Technology for Neuro-Psychology Lab., Istituto Auxologico Italiano, Milan, Italy. 2

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subject (first person)—we experience our body through different neural representations that are not related to its physical appearance.16,17 These frames also influence the way memories are stored and retrieved18–20: the rememberer may ‘‘see’’ the event from his or her perspective as in normal perception (field mode), or ‘‘see’’ the self engaged in the event as an observer would (observer mode). More, they influence the ability of representing and recalling our body: an egocentric representation of how our body looks is matched by an allocentric one, used by our brain in different situations,21,22 from spatial cognition to social perception. But what are the differences between field and observer modes of remembering? As Eich et al. clearly underline,18(p177) ‘‘ . adopting an observer perspective is tantamount to a literal disembodiment at the neural level. That is, when we choose to relive past events from a perspective outside our body, we shut down the neural circuitry in the insula that is central for monitoring our bodies’ internal states.’’ In simpler words, remembering our body in the observer mode overrides the actual contents of our bodily self-consciousness. If this process is impaired for either exogenous (i.e., high level of stress) or endogenous causes (i.e., alteration of brain areas), the experience of the body of the subject is locked to an old memory. In other words, OB and ED patients may be locked to an allocentric disembodied negative memory of the body that is not updated, even after a demanding diet and a significant weight loss. They cannot win23: whatever they do to modify their real body, they will be always present in a virtual body that they hate (e.g., ‘‘My body is fat’’). But if even successful dieting attempts are not able to improve body dissatisfaction, either people may start more radical dieting attempts, or, at the opposite end, all their attempts to control eating are abandoned and they engage in ‘‘disinhibited’’ eating behaviors. As presented and discussed in this special issue, VR can have a key role in the process of updating and improving the experience of the body. And the recent interest in the study of multisensory bodily illusions, among which the rubber hand illusion (RHI) is the main paradigm, may further improve the clinical potential of VR. In this illusion,24 feelings of ownership over a false hand are induced by synchronized stimulation of the real hand (by touch) and of the false hand (by sight). Many of these studies have been conducted using VR, allowing the manipulation of the perspective (first person, third person) from which the body itself is observed in a way that would not be possible with other procedures. Petkova and Ehrsson25 expanded this illusion to the whole body, and other studies have shown that the modulation of these illusions can also produce perceptual changes to the shape and size of the actual body, for example the illusory elongation of an arm26,27 and illusory expansion of the stomach.28 The production of the RHI involves a three-way interaction between the sensory modalities of touch, vision, and proprioceptive perception of body position in space. Using the RHI paradigm in patients with eating disorders, Eshkevari et al.29 found that when visual and tactile sensory information was incongruent with proprioception, individuals with an eating disorder experienced the RHI significantly more strongly than healthy controls did, as measured by both proprioceptive drift of the participant’s stimulated hand toward the rubber hand and self-reported experience of the illusion. Additionally, both the subjective self-reported

GUTIE´RREZ-MALDONADO ET AL.

experience of the RHI and associated proprioceptive biases were correlated with eating disorder psychopathology. These results suggest that people with an eating disorder have a heightened sensitivity to visual information, which dominates and overrides proprioceptive information. Keizer et al.30 also found that AN patients had a stronger experience of ownership over the rubber hand than healthy females did. Before induction of the illusion, AN patients overestimated hand width, but after induction (in both experimental and control conditions), AN patients no longer did so. Preston and Ehrsson31 used these illusions to investigate a causal link between body perception and body satisfaction. The full body illusion was induced over a mannequin body digitally manipulated to be both wider and slimmer than the participants’ actual body size. The results showed that the illusion of ownership over a slimmer body significantly decreases perceived body width and increases body satisfaction. In a later study, Eshkevari et al.32 explored whether this is a state phenomenon or a persisting individual trait that outlasts the period of acute eating disorder. The results indicated that dominance of visual information over information from other bodily senses could be a trait feature of individuals with eating disorders, which is further exacerbated during the acute stages of illness. This observation suggests that sensory training to increase the contribution of internal somatosensory information might restore an undistorted body representation. Increasing interoceptive and/or proprioceptive awareness should produce a less malleable and more accurate body perception. Disproportionate sensitivity to visual information about the body might then be reduced, and reliance on somatosensory and/or interoceptive information increased. All these results are in agreement with the results of a recent systematic review that explored nonvisual multisensory impairment of body perception in AN.33 The review suggests an altered capacity of AN patients in processing and integration of bodily signals: body parts are experienced as dissociated from their holistic and perceptive dimensions. Specifically, the studies suggest that not only perception but memory, and in particular sensorimotor/proprioceptive memory, shapes bodily experience in patients with AN. It is likely that some of the new interventions on eating disorders that derive from the allocentric Lock theory and from the findings related to multisensory bodily illusions may be enhanced by the use of VR. The manipulation of these illusions has already had some therapeutic success for other disorders thought to involve abnormalities in the cortical body representation.34,35 Research and Intervention at the Level of the Response: Cue Exposure

Though few studies have been carried out to date, CET has shown promise for the treatment of BN and other eating disorders.36 In 1988, Schmidt and Marks37 reported the first results of CET applied to patients with BN, and found that craving disappeared as the sessions progressed. In 1989, Jansen et al.38 reported a patient with BN who was effectively treated by cue exposure. Jansen et al.’s39 CET study reported effective results after even 1 year of follow-up. Cue exposure has been used in obesity as well as eating disorders.40,41 The procedure followed in most CET programs is to trigger the craving response and to maintain the length of each exposure session until the intensity of the craving decreases to a

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significant extent. Another approach is to focus on the reduction of anxiety rather than craving. It is generally agreed that anxiety, negative affect, and subjective distress can trigger episodes of binge eating.42,43 Patients may experience anticipatory anxiety in association with the presence of ‘‘forbidden’’ food and in relation to environmental and temporal cues; the cues that indicate the possibility of a binge provoke anxiety, which may lead, psychologically, to bulimic hunger. As a result, anxiety and hunger are experienced simultaneously in the presence of these cues. However, even though the live cue exposure technique can achieve positive results in patients resistant to standard treatments, it may also present considerable logistical difficulties. In the studies mentioned, for example, patients were asked to bring sufficient quantities of their own food to therapy sessions. Another limitation is to do with the ecological validity of the intervention; as it is performed in the therapist’s office, the setting does not include the contextual cues that may be relevant to the craving and anxiety in everyday situations. As VR places the exposure in the context of virtual environments that simulate natural situations, it may represent a valid way of overcoming these problems and may increase the effectiveness of these treatments. VR exposure achieves a high degree of control over the variables (internal validity) and also offers high generalizability to other contexts (external validity). These features are relevant to basic and applied research, as they influence the effectiveness of treatments. Many traditional experimental studies offer a high degree of control of variables but low external validity because this high control requires the creation of an artificial laboratory situation, which differs notably from the natural conditions in which the phenomena occur. This is also true of the application of psychological treatments such as cue exposure in a therapist’s office. In experimental studies, VR achieves the same degree of control as traditional laboratory studies, but with a higher ecological validity, since it facilitates the simulation of real situations.44 It offers the same advantages in psychological treatments in the therapist’s office, as it is possible to simulate the natural situations in which the disorder occurs,45 and the cues to which the patient is exposed are not decontextualized. VR has mainly been applied in treatments based on cue exposure in the field of addiction. Several research groups have studied VR treatment of addiction to substances such as heroin, nicotine, and alcohol.46–52 Virtual environments represent situations, people, or objects that are expected to trigger the desire to consume. The aim of the intervention is to eliminate or reduce this urge as far as possible, and then to extend this elimination or reduction to similar situations in the real world. In order to develop similar CET programs for patients with eating disorders, several studies are currently underway or have recently been published.53–55 One of these studies

sought to determine whether the level of craving experienced in VR environments incorporating cue exposure and contexts related to bingeing behavior was consistent with trait craving and state craving. As expected, participants with the highest scores on trait craving and state craving also showed a greater urge to eat when exposed to food in different VR environments. In addition, scores on questionnaires assessing trait craving and state craving were able to predict the average craving experienced in virtual environments. A clinical trial underway at several centers in Spain and Italy is currently investigating these issues (ClinicalTrials.gov identifier: NCT02237300; https://clinicaltrials.gov/ct2/show/ NCT02237300). Sixty patients diagnosed with BN or binge eating disorder according to the DSM-5 are participating in the study. They are all considered treatment resistant: that is, after the first 10 standard CBT sessions, all present persistence of binges at least once a week. Patients are randomly assigned to one of two booster session conditions: a VR-based cue exposure (VR-CE) booster session group, and a CBT booster session group (control group). Booster sessions consist of six 60-minute sessions held twice weekly over a period of 3 weeks. Over the six sessions, participants in the experimental group are exposed to different VR environments related to binge behavior, according to a previously constructed hierarchy. During exposure, patients face high-risk situations for reducing or extinguishing the conditioned response of anxiety when exposed to food-related cues and handle the virtual foods using a computer mouse. Exposure ends after a significant reduction in the level of anxiety, or after 60 minutes. Participants in the control group receive six CBT booster sessions to improve treatment outcome. In this treatment program, patients are trained to self-monitor their food patterns and to identify and manage thoughts, emotions, and environmental factors related to disruptive eating behaviors. A significant interaction between group (VR-CE vs. CBT) and time is expected in the first block of analyses. If this result is confirmed, it would indicate that the number of binges and purges remains stable before and after the booster sessions and during follow-up in the control group (CBT), but falls in the experimental group (VR-CE) after treatment and during follow-up. Technological Advances in VR Instruments

Traditionally, immersion and presence have been considered central to the quality of a VR system.56–58 Immersive VR is considered a special and unique experience that it is not achieved by simple three-dimensional (3D) interactions on desktop PCs. As a result, previous research has focused on the factors that contribute to the level of immersion in virtual environments.59–61 However, authors are also interested in looking for situations when highly immersive systems are unnecessary.

Table 1. Low-Cost Immersive Headsets Head-mounted display Oculus Rift Htc Vive Razer OSVR Samsung Gear VR Google Cardboard

Web site

Required hardware

Price

www.oculus.com/en-us/ www.htcvr.com www.razerzone.com/osvr www.oculus.com/en-us/gear-vr/ www.google.com/get/cardboard/

PC PC PC and Mobile (not yet available) Mobile Mobile

US$350 US$350 US$300 US$199 US$5/60


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Indeed, Banõs et al.62 found important differences in the responses to VR environments between control and clinical samples and observed that emotions may play an important role when the goal is to reduce or modify these responses. They suggested that if the content design is emotionally engaging, immersive systems are not always necessary.63 Thus, although immersive systems undoubtedly play an important role in reproducing life-like situations, other aspects are equally important. Typical VR systems for exposure involve graphical user interfaces for human–computer interaction that vary depending on the required level of immersion. The most basic level involves exposure to virtual environments on computer screens, with peripheral input devices (e.g., a keyboard or a computer mouse) used to interact with them. At the other extreme are innovative, technologically advanced systems such as head-mounted displays (HMD). Although HMDs can increase the user’s immersive experience, their use has several drawbacks. For example, they can be impractical in clinical settings,64 as clinical centers are often reluctant to include VR interventions in their daily practice if it involves the use of expensive or technically complex instruments. Another concern is that HMD may lead to side effects such as simulator sickness, which is estimated to occur 20% of the healthy population,65 or visual fatigue. Sex differences in simulator sickness have also been noted, with higher rates among women than among men.66 In addition to these practical issues, the price of immersive HMDs with a good tracker system has been generally prohibitive until recently, and this has delayed the development of advanced virtual environments for routine clinical practice.67 Several low-cost immersive HMDs have appeared on the market in recent years, among them the Oculus Rift, Razer OSVR, and HTC Vive (see Table 1), and which allow greater immersion at relatively economical prices. However, a certain level of technical knowledge is still needed to use these low-cost HMDs properly, and the need for training may present a barrier to their wider clinical application. Therefore, although low-cost HMDs offer an economic solution, the technological drawbacks remain. Recently, there has been a trend toward using smartphones as alternative VR systems, in combination with specially designed headsets (Samsung Gear VR) or even cardboard ones (Google Cardboard, see Table 1). Mobile seems a logical platform for the future of VR. Using classical PC-based VR, the illusion is compromised by the dim awareness that you remain attached to a PC via a cradle of wires. Mobile devices will offer a more liberating and self-contained experience. Not only are they self-contained but also cheaper to buy and run, both for the therapist and the patient. A recent study by Gutierrez-Maldonado et al.68 studied the effectiveness of a VR-CET program to reduce craving, comparing a highly immersive and a nonimmersive approach, in 113 college students (90 women and 23 men). Each participant was randomly assigned to one of the two exposure conditions, the first with an immersive VR system (HMD Oculus Rift) and the other with a nonimmersive system (a laptop with a stereoscopic screen). The analyses showed that the average craving experienced during VR exposure was significantly lower than the average craving reported by participants during the assessment prior to exposure. This reduction was similar in the two experimental conditions (highly immersive and

nonimmersive), in which both sets of subjects presented significant decreases in craving response after exposure to VR environments. Two conclusions follow from these results. The first is that repeated, systematic exposure to food-related virtual environments seems able to reduce the craving response in the nonclinical population. Second, although the use of HMD in clinical psychology helps to focus attention on the task being carried out and makes the experience more realistic, the lowcost nonimmersive VR systems (including the use of 3D laptops) also achieve significant effects. Bearing these results in mind, the progressive expansion and incorporation of economical, user-friendly VR devices is likely to dispel the reluctance of mental health professionals to use VR technology. In our view, the two factors that are currently holding back the widespread use of VR technology in the clinical setting in general and in EWDs in particular are the high cost and complexity of its use and maintenance. The first of these barriers is about to disappear. As noted above, high-quality, highly immersive HMD devices are now available at a remarkably low cost. Until recently, they were practically handmade instruments for laboratory use alone, but the introduction of consumer electronics has brought about a drastic reduction in their cost. It is to be hoped that, as their price falls, these devices will also become more userfriendly. When this happens—that is, when clinicians who use them to perform evaluations or interventions can do so by themselves without the need for technical assistance, as may happen with the diffusion of smartphone-based VR—the use of this type of technology will grow exponentially. Psychological interventions are not always carried out in large health institutions with specialized technical staff; in fact, in most cases the intervention teams comprise only psychologists or health professionals. In this situation, practitioners need to have access to technologies that are economical and easy to use. Significant progress in this direction has already been made. Support should now be provided for the testing of new devices as they become available in order to assess the value of VR in clinical and health psychology as a whole, and more specifically in the field of EWDs. Acknowledgments

The first author was supported for this study by the Spanish Ministry of Science and Innovation (Project PSI2011-28801: ‘‘Virtual Reality Cue-Exposure Treatment for Bulimia Nervosa’’) Author Disclosure Statement

No competing financial interests exist. References

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Address correspondence to: Dr. Jose´ Gutie´rrez-Maldonado University of Barcelona Faculty of Psychology Paseo Valle de Hebron, 171 08035 Barcelona Spain E-mail: [email protected]