25.1 Introduction

25.1.1 Virtual Reality: A Definition

What is Virtual Reality (VR)? If we follow the Oxford English Dictionary, the meaning of VR is: “A computer-generated simulation of a lifelike environment that can be interacted with in a seemingly real or physical way by a person, esp. by means of responsive hardware such as a visor with screen or gloves with sensors.” (online: http://www.oed.com/view/Entry/328583?redirectedFrom=virtual+reality). In this definition VR is described as a set of fancy technologies [1,2,3]: an interactive 3D visualization system (a computer, a game console, or a smartphone) supported by input tools (trackers, gloves, joystick, mice, etc.) that continually report the position and movements of the users; and output tools (visual, aural, haptic, etc.) that immerse the user in the virtual environment.

On the basis of the hardware and software included in a VR system, it is possible to distinguish between:

  • Desktop VR: It uses as main output tool a standard PC screen. The feeling of immersion can be improved through stereoscopic vision. Input tools usually include a mouse, joystick, or typical VR peripherals such as a data glove.

  • Fully Immersive VR: It uses advanced output devices (head-mounted display, force feedback robotic arms, etc.) and a system of head/body tracking to guarantee the exact correspondence and co-ordination of users’ movements with the feedback of the environment. In immersive VR, the user appears to be fully inserted in the computer-generated environment.

  • CAVE: This is a small room where a computer-generated world is projected on the walls. The projection is made on both front and side walls. This solution is particularly suitable for collective VR experiences because it allows different people to share the same experience at the same time.

NASA recently provided a less technical definition of VR: “the use of computer technology to create the effect of an interactive three-dimensional world in which the objects have a sense of spatial presence. In this definition, ‘spatial presence’ means that the objects in the environment effectively have a location in three-dimensional space relative to and independent of your position. Note that this is an effect, not an illusion. The basic idea is to present the correct cues to your perceptual and cognitive system so that your brain interprets those cues as objects” out there “in the three-dimensional world”. (Online: https://www.nas.nasa.gov/Software/VWT/vr.html).

In this view, what distinguishes VR from other media is the sense of “presence,” i.e., the feeling of “being there,” in the synthetic experience produced by the technology [4, 5]. While there is still no general consensus about what presence actually is from a psychological viewpoint (for an introduction to the subject, see [6]), it is fair to say that most investigators agree about what it is not [7, 8]. As underlined by Riva and colleagues [9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25] “presence is not the degree of technological immersion, it is not the same thing as emotional engagement, it is not absorption or attention or action; but all of these have a potential role in understanding the experience of presence in interaction – the experience of interacting with presence” (p. 1).

25.1.2 The Clinical Use of VR

The sense of presence and emotional engagement offered by VR can be a powerful tool for personal change because it provides a high level of personal efficacy and self-reflectiveness [26]. As underlined by Glantz and colleagues [27]: “One reason it is so difficult to get people to update their assumptions is that change often requires a prior step – recognizing the distinction between an assumption and a perception. Until revealed to be fallacious, assumptions constitute the world; they seem like perceptions, and as long as they do, they are resistant to change” (p. 96). On one side, VR offers synthetic worlds in which an individual can be placed and live a particular experience [28]. More, VR allows a higher level of self-reflectiveness than that provided by memory and imagination, and a higher level of control than that offered by direct “real” experience [29]. In fact, VR has also been described as an experiential form of imagery that is as effective as reality in inducing emotional responses [30].

These features clearly explain the increasing use of VR in clinical psychology. In a recent publication, Riva et al. [29] reported the available reviews and meta-analyses about the use of VR in clinical and health psychology. They were related to addictions (2 reviews, 1 meta-analysis; 53 studies), pain (4 reviews; 48 studies), anxiety disorders (3 reviews, 4 meta-analyses; 175 studies), stress-related disorders (4 reviews; 41 studies), depression (1 review and meta-analysis; 19 studies), EDs (3 reviews; 33 studies), schizophrenia and other psychotic disorders (2 reviews, 1 meta-analysis; 23 studies), and autism (2 reviews; 39 studies). The highest number of studies has been conducted in anxiety disorders and stress-related disorders, supporting the efficacy of VR in the treatment of phobias, stress management, post-traumatic stress disorder, panic disorder, and agoraphobia. The evidence for the treatment of social phobia is not definitive. The reviews related to addictions show that VR is effective in inducing craving to substances such as cocaine, alcohol, and tobacco, allowing its use in cue exposure treatments and to develop coping skills. In autism, the reviews support the use of VR to train social skills. This kind of training has also been used in patients with schizophrenia, and preliminary results are promising, but there is still no strong evidence for the efficacy of VR in the treatment of this disorder and other psychotic disorders. Similarly, there is only evidence for a moderate effect of the VR interventions on depression. As a pain reduction technique, VR has shown strong efficacy in short-term interventions, but little evidence exists for longer-term benefits. In EDs, the reviews performed to date show that VR cue exposure to food stimuli and VR body image treatments are effective [31]. We will discuss more in detail these results in the next paragraphs.

25.1.3 Virtual Reality Technology

The implementation of VR-based applications for clinical use has always depended heavily on the development of advanced technology. Consequently, for a long time the research in this area was limited by the cost of the technology required. Furthermore, the field was largely restricted to academic research and very few technology companies sought to transfer the results of this research into clinical VR applications.

Today, however, VR technology is advancing quickly. Both Oculus Rift (http://www.oculus.com) and HTC (https://www.htcvive.com/) are showcasing high-quality VR experiences at reasonable price points—less than $2000 for a fully configured system—which are now widely available to consumers [32]. Thus, the first major obstacle to the widespread use of the VR seems to have been overcome. The second one, the presence of technological difficulties, remains, but probably not for very long. The use of VR systems involves the management of complex devices that require a certain level of technological knowledge and the assistance of technical staff. Therefore, it is not surprising that some therapists and clinicians, especially veteran practitioners, are reluctant to introduce VR systems into their daily practice. However, this scenario is about to change largely due to the expansion of VR in the field of consumer electronics; the commercialization of VR systems among the general population will bring down costs and enhance the development of user-friendly devices. Furthermore, for younger generations the use of VR technology will be part of their everyday routine and the technical difficulties will disappear.

25.2 Virtual Reality Applications in Eating and Weight Disorders

As discussed widely in other chapters of this book, body image disturbance is a central feature of eating and weight disorders (EWDs) and plays an important role in the development, maintenance, and risk of relapse of these conditions [6, 29, 33, 34]. However, the study of body disturbances is not easy. In fact, our experience of the body is not direct (Fig. 25.1), but it is [35,36,37]:

  • Mediated by perceptual information.

  • Influenced by internal information.

  • Recalibrated through stored implicit and explicit body representation (body memory).

Fig. 25.1
figure 1

From the experience of the body to body image disturbances

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More, body image distortion can be seen as a multidimensional construct (Fig. 25.1) that, according to neuroimaging studies [38,39,40,41,42,43,44,45], includes three different components: cognitive, affective, and perceptive. The cognitive and affective components of body image distortion are widely accepted and related both:

  • To brain dysfunctions [37, 40, 46]: alterations of the prefrontal cortex, the amygdala, and the insula [47], and

  • To sociocultural issues [41, 46, 48]: internalization of an ideal body figure [43], social body comparison [49,50,51], and self-objectification [52].

Recent different functional magnetic resonance imaging (fMRI) [53] also suggest a perceptual component of body image distortion. According to Gaudio and colleagues “several brain regions could be involved body image disturbances and may sustain an impaired integration between real and perceived internal/external state of one’s own body in AN patients” (p. 582).

Given the complexity of body image, researchers usually target only one of the different components of body image disturbances [54,55,56]:

  • The perceptual distortion of body image: the inability to perceive the size of the body accurately, and

  • The cognitive/affective body dissatisfaction: the degree to which a person likes or dislikes the size and shape of his/her body and values it.

This complexity can also explain why body image disturbance is often overlooked in EWDs treatments, despite being considered a core feature of these disorders.

In this context, the development of VR has provided researchers and clinicians with a new technology that seems to be particularly well suited to the study, assessment, and treatment of body image disturbances for its ability of targeting all these dimensions. The use of immersive VR systems brings patients face to face with their virtual body in its actual size. More, VR simulates real-life situations in which different aspects of body image disturbances can be studied, assessed, and even treated in a secure, private, and controlled setting [57, 58]. Moreover, the possibility of developing three-dimensional figures that represent the body of the participants and whose size and shape can be modified enables patients to embody their mental representations of the different components of body image (e.g., perceived vs. ideal body image). Finally, VR allows bodily illusions [59,60,61,62]—the controlled illusory generation of unusual bodily feelings, such as the feeling of ownership over a virtual limb, that affect the experience of a body part or the entire body (i.e., body-swap illusion)—whose results have been presented in three recent reviews [63,64,65] and will be further discussed in the next paragraphs.

25.3 Virtual Reality for the Treatment of Body Image in EWDs: The Rationale

Most women are dissatisfied with their body [66]: one adolescent girl out of two reports body dissatisfaction [42]. For this reason, the “objectification theory” suggests a significant role of culture and society in the etiology of these disorders. Introduced by Fredrickson and Roberts [67], this theory suggests that our culture imposes a specific self-evaluation model—self-objectification—that defines women’s behavioral and emotional responses [68].

At its simplest, the objectification theory holds that [69]:

  1. 1.

    There exists an objectified societal ideal of beauty (within a particular culture).

  2. 2.

    This is transmitted via a variety of sociocultural channels.

  3. 3.

    This ideal is then internalized by individuals.

  4. 4.

    Satisfaction (or dissatisfaction) with appearance will be a function of the extent to which individuals do (or do not) meet the ideal prescription.

According to Fredrickson and colleagues [70, 71], repeated experiences of sexual objectification—when women are treated as bodies that exist for the use and pleasure of others—cause them to gradually adopt an observer’s perspective of their physical self; that is, they begin to treat themselves as an object to be looked at and evaluated on the basis of physical appearance. The self is so defined in terms of how the body appears to others.

The internalization of an observer’s perspective on one’s own body is labeled as “self-objectification” [72] and reduces a woman’s worth to her perception of her body’s semblance to cultural standards of attractiveness [69]. Self-objectification is typically manifested as persistent body surveillance or habitual monitoring of the body’s outward appearance and is believed to lead to different negative experiential consequences such as body shame, social physique anxiety, lack of awareness of internal bodily states, and decreased peak motivational states/flow experiences [73, 74], and is recognized as the most robust risk factor for clinical and subclinical EWDs [43, 75].

There are two possible criticisms of this view. The first is that males, who apparently are less prone to self-objectification, also experience EWDs. Second, only a small subset of all the female and male subjects exposed to idealized body models develop clinically diagnosable EWDs [76].

Nevertheless, different recent studies have underlined the possible role of self-objectification in the etiology of male EWDs [43, 71, 76,77,78]. Specifically in males, self-objectification is manifested as body surveillance [79].

A possible response to the second criticism is offered by a new etiological model, i.e., the “Allocentric Lock (AL) Theory” [20, 52, 80,81,82]. This theory suggests that EWDs, including anorexia nervosa, are the outcome of a deficit in the processing and integration of multisensory bodily representations and signals [40, 83, 84] that alters the way the body is “experienced” and “remembered.” Specifically, individuals with (or developing) this disorder may be locked to an allocentric (third person) disturbed memory of their body that, independently of its causes, is not more updated by experiential data, even after a successful diet and/or a significant weight reduction (Fig. 25.2).

Fig. 25.2
figure 2

The allocentric lock theory

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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 subject (first person)—we experience our body through different neural representations that are not related to its physical appearance [85].

These frames influence also the way memories are stored and retrieved [86, 87]: 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 [88]: from spatial cognition to social perception.

But what are the differences between field and observer modes of remembering? As Eich and colleagues clearly underline [87]: “…adopting an observer perspective is tantamount to a literal disembodiment at the neural level.” (p. 177). 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 neurotransmitters and/or brain areas), the experience of the body is locked to an old memory.

From a cognitive viewpoint, this situation can be explained as the effect of a functional disconnection between top-down, premorbidly learned predictions regarding the experience of the body and the processing of bottom-up perceptual information regarding its current state [20, 74].

More, this theory also fits well with the recent neurobiological model developed by Kaye and colleagues [89, 90] suggesting that AN patients are characterized by a dysregulation in the anterior ventral striatal pathway that may create a vulnerability for dysregulated appetitive behaviors. One of the effects of this dysregulation is an altered serotoninergic activity [91,92,93,94] related to the impairment of serotonin (5-HT) neurotransmitters. As discussed in a recent review [40], serotonin disturbances may (see Fig. 25.2):

  • Facilitate the encoding of allocentric (from outside) episodic memories.

  • Facilitate the consolidation of emotional episodic memories (e.g., teasing), if preceded by repeated stress.

  • Reduce voluntary inhibition of mnestic contents.

  • Impair allocentric spatial memory.

If we discuss these data within the interpretative frame suggested by the allocentric lock hypothesis, it is possible to hypothesize that these patients [40]:

  1. (a)

    Are more able to store and consolidate negative autobiographical memories, including those of their body, in allocentric perspective.

  2. (b)

    Have an impaired ability to trigger voluntary inhibition of the previously stored negative memory of the body, impairing their possibility to disengage and update it during the reconsolidation process.

  3. (c)

    Have an impaired capacity to retrieve and update allocentric information.

In conclusion, there is a possible link between serotonin dysfunctions and body image disturbances in AN: the impossibility of updating a disturbed body memory using real-time experiential data—I’m locked to an old negative body stored in long-term memory—pushes patients to control body weight and shape even when underweight. Moreover, if even successful dieting attempts are unable to balance body image disturbance, people may either 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 that can be followed by compensatory behaviors, which can turn into a vicious cycle (for a broader review, see [95, 96]).

25.4 Virtual Reality for the Treatment of Body Image in EWDs: Protocols and Studies

To modify this situation, the use of VR, a synthetic egocentric experience, is an emerging and promising approach [97,98,99,100]. In particular, the two research groups mentioned above (Riva’s group in Milan and Perpiñá’s group in Castellón and Valencia) are using VR to improve CBT, and have also developed VR-based software for the assessment and treatment of body image disturbances [101].

The first approach is offered by VR-enhanced cognitive behavior therapy called Experiential Cognitive Therapy (ECT) developed by Giuseppe Riva and his group inside the VREPAR and VEPSY Updated European funded projects. It is a relatively short-term, patient-oriented approach that focuses on individual discovery [102]. ECT shares with CBT the use of a combination of cognitive and behavioral procedures to help the patient identify and change the maintaining mechanisms. However, it differs from CBT in the following ways:

  • Use of VR: There are 15 VR sessions. The first session is used to assess any stimuli that could elicit abnormal eating behavior. Specifically, attention is focused on the patient’s concerns about food, eating, shape, and weight. At the end of the first VR session the therapist uses the miracle question, a typical approach used by the solution-focused brief therapy [103,104,105,106]. Using VR to experience the effects of the miracle [34, 107,108,109,110] individuals are more likely not only to gain an awareness of their need to do something to create change but also to experience a greater sense of personal efficacy.

  • Focus on the negative emotions related to the body (a major reason patients want to lose weight) and on supporting the empowerment process. In eight VR sessions, the therapist helps patients to recognize why they eat and what they need to either avoid or cope with specific emotional/behavioral triggers. Cue exposure techniques are also used [111, 112]. During exposure, patients face high-risk situations for reducing or extinguishing the conditioned response of anxiety when exposed to food-related cues [113, 114]. Exposure ends after a significant reduction in the level of anxiety.

  • Focus of the experience of the body: VR is used in a sensory training to unlock the body memory (body image rescripting protocol) by increasing the contribution of new egocentric/internal somatosensory information directly related to the existing allocentric memory [31, 115]. In the protocol (see Fig. 25.3), involving six VR sessions, different body-related situations are experienced from both first-person (the patient does not see his/her body in the scene) and third-person perspectives (the patient sees his/her body in the scene) integrating the therapeutic methods used by Butter and Cash [116] and Wooley and Wooley [117].

Fig. 25.3
figure 3

The VR body image rescripting protocol (Adapted from Riva et al. 2006, Riva, 2011)

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This approach was validated by various case studies [3, 118] and trials [107, 119,120,121,122].

The most recent controlled trial (ISRCTN59019572) included 211 obese (BMI>40 female patients and 90 obese (BMI>40) female patients with BED [109, 110]. In the trial ECT was compared with CBT and an integrated treatment (IT) including nutritional groups, a low-calorie diet (1200 kcal/day) and physical training.

In both studies [109, 110], only ECT was effective at improving weight loss at 1-year follow-up. Conversely, control participants regained most of the weight they had lost during the inpatient program.

Furthermore, in the BED study [109] binge eating episodes decreased to zero during the inpatient program but were reported again in all the groups at 1-year follow-up. However, a substantial regain was observed only in the group who received the integrated treatment alone, while both ECT and CBT were successful in maintaining a low rate of monthly binge eating episodes.

To further improve the efficacy of ECT, Riva and colleagues recently started to explore the possibility of integrating the emerging field of bodily illusions in the protocol [115, 123]. A first study [97] showed that the body-swap illusion was able to update the negative stored representation of the body. It has been found that after embodying a virtual body with a skinny belly, women updated their “remembered body,” reporting a significant (post-illusion) decrease in their body-size distortion. A similar result was obtained recently by Keizer and colleagues [124] using body swapping with a sample of 30 anorectic subjects: they decreased the overestimation of their shoulders, abdomen, and hips both after the illusion was induced and after a short follow-up (2 h and 45 min after the illusions).

Support for the use of bodily illusions to alter the dysfunctional experience of the bodily self also came from a recent published study [125] showing that a (VR) body-swap illusion, which generates the (converse) illusion that a fat person is thin, was able to increase body satisfaction and reduce body-size distortion in a non-operable super-super obese patient (i.e., with body mass index >60 kg/m2). In addition to the improvement in the bodily experience, the illusion was able to increase the patient’s motivation to maintain healthy eating behaviors. While no studies to date have directly exploited the potential of bodily illusions in ED treatment, the evidence deriving from the extant experimental studies may suggest clinical applications for these methods [65, 126, 127].

Preston and Ehrsson [128] also used these illusions to explore the relation between body satisfaction and body perception. The body swapping 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. Preston and colleagues [129] also used multisensory full-body illusions to modulate feelings of ownership over a mannequin body. The third-person mirror perspective elicited strong feelings of ownership over the mannequin and increased physiological responses to the mannequin being threatened. This result suggests that mirrors are special for viewing the self by providing a unique first-person perspective of our body from the outside. In a later study, Preston and Ehrsson [130] used multisensory illusions to elicit illusory ownership of obese and slim bodies during functional magnetic resonance imaging. Their results suggest the involvement of the anterior insula and the anterior cingulate cortex in the development of negative feelings toward the body through functional interactions with the posterior parietal cortex, which mediates perceived obesity.

Perpiñá’s group compared the effectiveness of VR with that of CBT for body image improvement. Specifically, they developed six different virtual environments, including a 3D figure whose body parts (arms, thighs, legs, breasts, stomach, buttocks, etc.) could be enlarged or reduced. The proposed approach addressed several body image dimensions: the body could be evaluated wholly or in parts; the body could be placed in different contexts (for instance, in the kitchen, before eating, after eating, facing attractive persons, etc.); behavioral tests could be performed in these contexts, and several discrepancy indices related to weight and figure could be combined (actual weight, subjective weight, desired weight, healthy weight, how the person thinks others see her/him, etc.).

In the published trial, 18 outpatients who had been diagnosed as suffering from EDs disorders (AN or BN) were randomly assigned to one of the two treatment conditions: the VR condition (CBT plus VR) and the standard body image treatment condition (CBT plus relaxation). The results showed that all patients improved significantly following treatment. However, those who had been treated with the VR component showed a significantly greater improvement in general psychopathology, ED psychopathology, and specific body image variables. What is more, these results were maintained at 1-year follow-up [131].

This group’s most recent controlled trial included 34 patients diagnosed with ED [42]. Seventeen patients underwent VR-enhanced CBT and 17 classical CBT. The CBT program for EDs enhanced by a body image-specific component using VR techniques was shown to be more efficient than CBT alone. Furthermore, improvement was maintained in post-treatment and at 1-year follow-up.

Conclusions

VR has proven to be a useful technology in the study, assessment, and treatment of a variety of psychological disorders. Studies on the application of this technology in the treatment of EDs were some of the first ones conducted in the early 1990s. Since then, several VR applications have been developed to be used in conjunction with traditional treatments, and their effectiveness has been tested in case studies, as well as in non-controlled and controlled trials. VR-based interventions in EDs usually combine exposure to VR environments with components based on CBT.

Although various longitudinal studies highlight the unhealthy weight-control behaviors used to counter body dissatisfaction as the common antecedents of eating and weight disorders, trans-disciplinary 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” [20, 43, 52, 74, 82, 83]. The key hypothesis of this framework is that both OB and EDs [i.e., Anorexia Nervosa (AN) and Bulimia Nervosa (BN)] are the outcome of a deficit in the processing and integration of multisensory bodily representations and signals [40, 83, 84] that alters the way the body is “experienced” and “remembered”: EWDs 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 win: whatever they will do to modify their real body, they will be always present in a virtual body that they hate (e.g., “My body is fat”).

As presented and discussed in this chapter, virtual reality can have a key role in the process of updating and improving the experience of the body [5]. So, it is likely that some of the new interventions on EWDs that derive from the allocentric lock theory and from the findings related to multisensory bodily illusions may be enhanced by the use of virtual reality, as recently demonstrated by different pioneering studies [65, 124, 125].

In conclusion, the two factors that are currently holding back the widespread use of VR technology in this field are the high cost and complexity of its use and maintenance [28]. 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 [32]. 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.