Virtual reality (VR), is a technology enabling users to experience an immersive three-dimensional environment in a realistic fashion. A head-mounted display presents binocular imagery with a large field of vision and responds to head movements and physical position in space. Other technologies can be incorporated such as earphones, gloves, eye-tracking and biofeedback capabilities to increase the feeling of immediacy. This rich set of inputs allows a computer system to render a natural feeling of presence as the virtual environment changes with the motion of the user (please refer to section on presence for further explanation). The multimodal components work together to avoid a passive feeling of watching images on a screen, and rather, allow for an immersive and interactive experience. This means that researchers and therapists can deliver, observe and record in real-time with individuals in naturalistic and controlled environments.
The concept of VR technologies first emerged in the 1950s (Park et al., 2019); however, they were traditionally expensive and cumbersome, and required substantial technical expertise to use and maintain. The technology has been steadily advancing but only in the last decade has VR become widely accessible due to releases of high-end and low-end devices onto the consumer market. Headsets have become more portable with VR apps now available even on smartphones. Due to international efforts in standardisation and interoperability, software has become easier to design and develop. For mental health, this has meant that exploration and therapy has become more feasible, enabling researchers and clinicians to conceive and deliver programmes without extensive prior training.
These developments in VR could make mental health more egalitarian and more personalised, allowing for at-home self-administered interventions or assessments, and even longitudinal studies. This technology may also be invaluable for those who are unable to leave their home, or do not wish to see a therapist. Such a highly adaptable toolset can also be effective in fields outside of mental health, for example for individuals with brain injury or neurological diseases. It can be used for rehabilitation or diagnosis, as well as establishing the causes of mental health disorders. For these reasons, VR has been predicted to rapidly expand over the next decade (Norcross et al., 2013).
VR has also many other advantages, especially when compared with in vivo treatments (although it can be used in conjunction with in vivo techniques, which we will discuss later).
- In vivo exposure therapy may require a clinician to work with animals, or, in the case of social or flying phobia, take a therapy session outside of the treatment room. This can be expensive, difficult to control and may raise ethical concerns.
- VR creates a replicable, controlled environment which can be easily manipulated and personalised, but also feels realistic and induces a feeling of presence. This differentiates it from other kinds of computer-based interventions or assessments.
- VR is well tolerated, with many patients preferring VR to in vivo exposure (Freeman et al., 2017). The feeling of security may allow them to experience and then express thoughts or emotions which may be inhibited in a real-life situation and increase the degree of closeness between the patient and the therapist. The therapist can also guarantee what will and won’t happen, for example- turbulence on a flight. (Bell et al. 2020).
- The novelty and immersive nature of VR can minimise external distractors and enhance engagement, which can be helpful in a patient group with low adherence rates or concentration difficulties (Navarro-Haro et al. 2019).
However, there are some disadvantages to VR, and these should be highlighted and addressed as research in this area progresses.
- For some people, using VR can cause nausea and dizziness, also called ‘cyber-sickness’ (Slater et al., 2016).
- In some cases, VR may not elicit emotions or reactions as intensely as a real-life situation. However, VR can be viewed as an intermediate step allowing the user to become accustomed to confronting a situation or thought pattern, which should serve them in an analogous real-life experience.
- A recurring pattern in the literature shows very little standardisation in VR software and technology, as well as in the protocols implemented (Freeman et al. 2017). As this is an emerging field, many researchers have created apps for use in proof-of-concept exercises with small sample sizes. These are usually not repeated. While such studies may have demonstrated promising results, they lack the robustness and validity needed for clinicians to reliably use them in wide-ranging contexts. There is a need for more consistent apps, which are tested and validated for a target symptom and population.
- Finally, researchers and clinicians may find it difficult to incorporate VR into their work in a fluid way. They may need additional training to use equipment and deal with software glitches (Maples-Keller et al, 2017). This also requires developers to gain further understanding of what occurs in therapy and what is and isn’t possible to integrate. Again, this is something which further research, standardised protocols and advances in the consumer gaming technology market may help with.
As will be discussed in our next instalment, currently a large majority of the research conducted concerns the treatment of anxiety disorders (Freeman et al. 2017), but we also hope to look at the potential of VR in other areas in mental health and neurological disorders.
A brief explanation of the concepts of presence and ecological validity is included here as these are considered to be mediating or moderating variables and are vital in understanding how effective a VR programme or protocol is.
‘Presence’ in VR removes the separation between the user and the simulated environment. It is used to refer to the feeling of being in an environment which is simulated while also being aware that you are simultaneously in another place. It is important to note: “Except in the most extreme cases, the individual can indicate correctly that s/he is using the technology, but at *some level* and to *some degree*, her/his perceptions overlook that knowledge and objects, events, entities and environments are perceived as if the technology was not involved in the experience’’ (International Society for Presence Research, 2000).” This feeling of being immersed in an environment has been associated with engagement and motivation (Lombard et al., 1997; Retaux,2003), which could provide better outcomes when using programmes for assessment or intervention. Presence can be measured by objective (e.g., heart rate, body posture) or subjective measures (usually questionnaires such as the Igroup Presence Questionnaire (IPQ)) (Krijn et al. 2004). Measurement can be difficult however, as there is no one standard questionnaire and the objective measures can also be used to measure emotional responses such as anxiety or fear, risking conflating the variables. There may also be individuals more susceptible to presence than others and this needs further investigation (Krijn et al. 2004).
‘Ecological Validity’ is vital for research to be translated to a clinical setting. This is defined by (Bell et al. 2020) as “the degree to which the findings of research studies generalize to real-world settings”. In VR this is important, particularly when combined with the concept of presence, as presence may determine the ecological validity of study results. Findings appear to demonstrate that participants react to VR environments in a realistic way and that desired physiological and emotional responses can be targeted. Research studies have evaluated whether VR is capable of eliciting real emotions. While the results appear mixed due to the difficulty of controlling for physical exertion (e.g. the heart rate can be increased due to other factors) the findings show that emotion experienced during a VR session is similar to those during in vivo experiences (Marin-Morales et al., 2019; Regenbrecht et al., 2009). We will discuss these topics further in the next instalments of our review, where we focus on studies in a range of mental health conditions.
One of VR’s major advantages is its broad range and flexibility as a medium. (Riva, 2005) gives a good appraisal of how VR can be adapted depending on the background of the therapist (bottom up vs. top down approaches) and the nature of the issue the patient is presenting with. For example, with a behavioural (or bottom up) approach, -the VR environment can be used to activate the fear structure by exposing a patient to the phobic stimuli; with a cognitive (or top down) approach clinicians/researchers can use a VR environment to assess schema or confront habitual patterns or biases; and with an experiential approach, patients can carry out actions in a safe environment that gives them space to re-enact and re-experience emotional situations. As with a lot of research in VR, there is still room for further innovation, including examining new intervention approaches as well as progressing in the assessment of symptoms and diagnoses.
Later in the review, we will look at the various interventions in detail under diagnostic groupings as this shows how techniques can be well adapted to suit the patient. In the literature to date there has been a lot of focus on VR exposure therapy (VRET; Boeldt et al., 2019) which reflects that the majority of research to date in mental health has focussed on anxiety disorders. It also demonstrates the advantage of VR in the recreation of believable ‘real-world’ scenarios and its potential for ecological validity’ (Bell et al. 2020). Exposure therapy is based on emotional processing theory, which proposes that fear is activated by networks which include information about the stimulus, escape response to the stimulus, and the meaning of that fear. With intervention, these networks are activated and modified by presenting incompatible information (Maples-Keller et al., 2017). This makes VR a perfect resource as the sense of presence allows those fear networks to be stimulated in a secure way and incompatible information can be presented in a very controlled and tailored manner, which matches specifically with each patient.
Research has shown that VRET performs as well as in vivo therapy, and a meta-analysis has demonstrated a small effect size supporting VRET over in vivo therapies (Powers & Emmelkamp, 2007). VRET also appears to translate to real life and demonstrates its ecological validity; with a meta-analysis showing that VRET patients did better on behavioural assessments at post-treatment than waitlist, and no significant difference between VRET and exposure in vivo (Morina et al., 2015). It should be noted that VRET still relies heavily on the therapist to tailor the programme for the patient and to help to guide them through the exposure process and VRET can be commonly paired with cognitive behavioural therapy (CBT) techniques. Such blended approach relies on technology extending existing treatment rather than replacing it.
VR has been mostly used as an intervention in the literature to date. However, it also shows great potential as an assessment tool, which has yet been little explored. As noted by (Freeman et al., 2017), many diagnostic techniques such as interviews and questionnaires rely on the recall abilities of the patient, which can be very subjective and prone to error. VR could allow a clinician to assess a patient’s reactions and emotions in real-time and distinguish particular environmental triggers. (Bell et al., 2020) have classified current research using VR as an assessment tool into three main areas: social functioning, cognition and symptomatology. Social functioning can be assessed using data capture such as eye gaze, proximity to VR avatars, and observation of behaviour in social situations. Cognition can be studied with memory and executive function in maze navigation and attention tasks. Symptomatology can be elicited in VR environments; for example, paranoia in individuals with first episode psychosis (Veling et al., 2013), and triggers for addiction (Detez et al., 2019) and disordered eating (Ferrer-Garcia et al., 2015). Finally, a study looking at VR with skin conductance reactivity identified it as a promising diagnostic tool. For example, veterans with PTSD showed larger skin conductance reactivity in VR combat, but not for non-combat VR (van ‘t Wout et al. 2017).
These studies show that with a fresh perspective and a little imagination, VR can match and indeed exceed many of our current methods for research and treatment.
This introductory part of our literature review demonstrates the potential of utilising VR for interventions and assessment tools across a spectrum of mental health conditions. We have discussed the essential concepts and highlighted the overall advantages and disadvantages of VR innovation applied to date. This piece lays the foundation for the remaining two parts of our review.
The next instalment discusses the use of VR in anxiety disorders; spanning from specific phobias, social anxiety and panic disorders, to public speaking phobia, and obsessive-compulsive disorder.