Virtual Reality Exposure Therapy to tackle "Vertigo" complex

Delft 29 February 2000At the Delft University of Technology, a multi-disciplinary research team, headed by Drs. Martijn J. Schuemie, in 1999 started to build a Virtual Reality Exposure Therapy (VRET) environment for the treatment of obsessive anxiety, more specifically of acrophobia, which is a fear of heights. This four-year project running in close co-operation with the University of Amsterdam, will take into account the Human Computer Interface (HCI) issues unique to such a system, in order to create a real sense of presence for the patient. To this purpose, psychologists as well as computer graphics experts are playing a crucial role in the design. First, the researchers initiated a pilot study with low budget Virtual Reality equipment to obtain a better understanding of the basic VRET system requirements. A group of patients with acrophobia was treated in an environment depicting a swimming pool with two diving towers.

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Drs. M. J. Schuemie depicts phobias as the most familiar type of anxiety phenomena among the psychiatric disorders. In the Netherlands, up to 12.4% of the population is suffering from one or more phobias. Psychiatry has identified three different categories:

  • agoraphobia which is irrational anxiety about being in places from which escape might be difficult or embarrassing;
  • social phobia, described as irrational anxiety elicited by exposure to certain types of social or performance situations, also leading to avoidance behaviour;
  • specific phobia, defined as persistent and irrational fear in the presence of some specific stimulus, which commonly elicits avoidance of that very stimulus by withdrawal. Specific examples are acrophobia, fear of flying, spider phobia, fear of driving, claustrophobia, ...
Exposure therapy is applied to attenuate the anxiety by subjecting a patient to anxiety-producing stimuli in real life situations, referred to as "in vivo" or by evoking the stimulus in the patient's imagination. A third option constitutes the use of Virtual Reality, which offers the advantage of a safer setting, less embarrassing and more cost-effective than producing real world situations and more realistic than just imagining the danger.

Research in VRET is still in its infancy. To date, systems have been designed to demonstrate the effectiveness of VRET, but the question of which elements a good VRET system should consist and how this actually differs from in vivo and imaginary therapy largely remains unanswered. Therefore, the Schuemie team aims to validate criteria for a Human Computer Interface (HCI) in VRET systems by means of a task analysis based on the video recordings of several sessions in the treatment of fear of heights at the faculty of psychology at the University of Amsterdam. The Virtual Reality User Interface should be able to carry out a twofold job as an access tool for both patient and therapist to the functionality of a fully immersive Virtual Environment via CSCW, Computer Supported Collaborative Work, and as an exposure tool to generate a sense of presence by influencing the patient through vivid interaction.

A higher level of presence can increase a phobic response to a virtual anxiety producing stimulus, which is necessary for effective treatment. In fact, there are three major interactive variables acting upon the patient's virtual phobia experience which are the system's response speed to a task; the modification range of the six degrees of freedom tracking device within the Head Mounted Display, used in the experimental setting; and mapping, which is defined as the degree of correspondence between the type of user input and the type of medium response. In the test sessions, organised by the VRET team to find out which criteria are vital to HCI design, the therapist moved the patient to a location which could be scary to this person. It would be useful to provide a list of navigation points which could be programmed by the therapist and individualised for each patient.

After moving the patient to a location, the therapist instructed the patient to look at certain points and to evaluate whether the location produced enough anxiety. If so, the therapist left the patient in that particular location, usually accompanied by a long silence, until the fear had habituated. Ambiguities in the Virtual Environment however may distract the patient after being moved to a new location. As already been stated, the researchers intend to use the task analysis to improve the VRET process in the final system design. This will lead to a task model, which will take into account aspects necessary for turning the user interface into an effective exposure tool. Based on the task model, a User's Virtual Machine (UVM) will be designed as a description of the user interface.

Expert evaluation by means of the interface guidelines, and eventually a real user evaluation with prototypes will be applied to improve aspects of the HCI in an iterative design cycle. Research will probably demonstrate that the two roles of Virtual Reality can conflict. In this regard, the HCI can be developed in a way to make people move their bodies more frequently as to increase the sense of presence, at the same time causing the system to take more effort to operate efficiently. At this moment, Virtual Reality is only used for exposure treatment itself. More research is needed to find out whether this technology could also play a role in other parts of the therapy, such as diagnosis of the disorder. Drs. Schuemie carefully states that Virtual Reality may be effective in treating several types of phobia but, on the other hand, might cause other psychological problems such as self-fragmentation. Extensive information is available at the VRET project home page.


Leslie Versweyveld

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