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David Baxter

Mar 26, 2004
Playing Games with Painful Memories: Designing VR Exposure Therapy Simulations for PTSD
Ari Hollander

Virtual Reality Exposure Therapy is currently being examined in several contexts as a treatment for post-traumatic stress disorders. Going through therapy for PTSD is decidedly not a game, and exposure therapy typically involves highly structured graded exposure treatment therapy protocols. The Virtual World Designers, for whom worldbuilding is usually much more of an art than a science, need some research and therapy savvy design guidelines. This paper explores a few ideas in this vein, drawing from the PTSD therapy literature, video game development technology, and virtual reality theory. In particular one concept originally from the field of robotics, Masahiro Mori?s Uncanny Valley, is extended in its possible application as a useful metaphor for designing virtual environments for PTSD Exposure therapy

A soldier who had recently returned from Iraq told us that the most dangerous times were just after the loudspeaker evening prayers ended. This was often when the most brutal attacks by insurgents began. In designing Virtual Environments for post-traumatic stress disorders exposure, this is a situation where the mere cessation of a sound has the potential to create more tension and anxiety than you will ever experience in a video game. Although many of the tools and techniques that we use for building such environments are the same as those used to build video games, PTSD therapy is not a game.

The video game vernacular is tantalizing to a designer in this new field where conventions and constraints are scarce, but how we choose to draw on the metaphors from more established application domains is a question that needs to be considered carefully. Finding specific details like which sounds to play (and when to end them) is one of the many hard problems that face the designer and comes out of close consultation with the researchers and cybertherapists who do the hard work of conducting focus groups establishing therapeutic protocols and adapting them to employ virtual reality.

At Imprint Interactive, we are VR and game designers (none of us therapists) who have now worked on several VR exposure therapy applications. In this paper we attempt to synthesize the beginnings of some general design guidelines for the technologists by drawing connections between the requirements of the exposure therapy applications given to us by the therapists, and precedents from other application domains.

Exposure Therapy for PTSD
Imaginal exposure therapy (without virtual reality) is one of the most successful methods of treating post-traumatic stress disorders (PTSD)(1). It involves having a cognitive behavioral therapist with specialized training for PTSD serve as a guide in confronting memories of traumatic events(2). By helping the patient to imagine these events as if they were happening again and getting them to repeatedly tell their story it is often possible for the patient to come to terms with the memories and experience significantly reduced symptoms of PTSD.

While this technique is one of the most dramatically successful therapies around, it does suffer from a few vulnerabilities: It requires emotionally scarred individuals to repeatedly immerse themselves in their most painful memories. The challenge of gently bringing out these memories without causing further harm is not even the greatest challenge. Pathological avoidance of problematic memories is one of the primary symptoms of PTSD and may leave the patient unable to recreate the scenarios for themselves. However, what was formerly purely a question of technique is now partially becoming one of technology.

Virtual reality (VR) provides a tool that can allow therapists to gradually intensify a simulation of the traumatic events rather than relying on pure talk and storytelling. With VR, therapists have been able to bring out memories and stories that might have otherwise been inaccessible(3). Patients may also be more willing to seek VR therapy than conventional therapy, because of the stigma attached to conventional therapy (and the tendency of PTSD patients to avoid situations where they have to recount their traumatic experiences).

At the time of this writing, virtual reality exposure therapy for PTSD is a fairly new idea. At Imprint Interactive, we have been involved with a number of PTSD VR exposure therapy research projects, one of which has already been used to successfully treat patients. These include a simulation of the tragic events of 9/11/01 (We made minor modifications to the application originally built by Howard Abrams for Difede and Hoffman, 2002), a simulation of a terrorist bus bombing for a research group at the University of Haifa in Israel, and two simulations for treating U.S. soldiers returning from Middle East conflict.

Although the last three projects are still in their early phases, our ongoing communication with the therapy research teams including Dr. Hunter Hoffman, Dr. Sarah Miyahira, Dr. Ray Folen, Dr. Tamar Weiss and others has suggested some general ideas for how we might structure the technical components of the design process.

Design Goals
The research in PTSD treatment has shown that Imaginal Exposure Therapy requires the patient to engage emotionally in the process in order to be effective(4). This is a familiar goal in both game design and VR. In game design we call the engagement process ?fun? (we will not digress into that particular can of worms here). In VR we call the engagement process presence. Presence is the primary success metric in VR: when we create a sufficiently compelling software controlled environment that the users react to it as if it were an actual place, all kinds of magic can happen! In therapeutic applications, for example, we have built applications that have successfully been used by therapists to cure phobias(5) and alleviate pain in such a way that the reduction in pain-related brain activity can been seen on an fMRI brain imaging(6).

In virtual environments for PTSD exposure therapy, our first goal is to maximize presence. Presence is influenced by a collection of pure sensory factors such as field of view, frame rate, and tracking latency(7) and aesthetic factors that we will discuss below. The second goal is to make the environment sufficiently reminiscent of the patient?s experience that it evokes memories of the traumatic events. Achieving a personalized experience for each patient presents a challenge given that economics and expedience require single applications that can be used to treat many people. This requirement is simplified in cases where a large population has experienced a common overwhelming traumatic event, such as in the case of 9/11.

Difede and Hoffman were able to use a simulation of planes striking the World Trade Center(3) to administer therapy to patients in spite of the fact that each of those patients experienced the events of the day from a different vantage point and with different, very personal details. Similarly, in the bus bombing simulation we developed for the University of Haifa in Israel a single scenario is sadly becoming appropriate for a growing number of people.

In ongoing research projects the Veterans Administration, the US Army, and the Office of Naval Research are using VR Exposure therapy to treat soldiers afflicted with PTSD. We are developing a number of Middle East conflict simulations that include such common elements as sniper attacks, improvised explosive devices (IEDs), and rocket propelled grenade (RPG) attacks. These applications include functionality that allows therapists to dynamically control the intensity of the experience for the patient, increasing or decreasing the level of stimulation and tension according to the level of anxiety. The level of control computer simulations afford enables therapists to go beyond the limitations of conventional Imaginal Exposure Therapy, which relies on the patient's willingness and ability to push their own recall. It does, however, remain an open question as to whether this one simulation will span the great variety of soldier?s experiences.

This application was created for the Pacific Telehealth and Technology Hui and will be tested in a clinical study funded by Office of Naval Research (program officer Russ Shilling).

Design Guidelines
The need for broadly applicable simulations repeats and refines the call for the development of design methodologies for VR Exposure Therapy. Specifically: how do we determine what content and aesthetic factors contribute to both presence and reminiscence?

In his 1970 robotics paper The Uncanny Valley (7) Masahiro Mori drew a curve that described the ?familiarity? of anthropomorphic robots. As robots are made more realistic (i.e. more like humans) they become more compelling?to a point. The curve reaches a peak and then takes a plunge into what Mori called the ?Uncanny Valley? where the simulation becomes rapidly less compelling and then actively repellent when our perceptual system switches over from noticing the life-like aspects of the robot to underlining the discrepancies. This curve has been correctly criticized as being unscientificii, largely due to the fact that there is no one-dimensional quantity that completely characterizes realism. The true value in this curve is in its use as a metaphor to guide design.

The Uncanny Valley metaphor been also been generalized to cover discussions of presence in virtual environments(9). Our job as virtual environment designers is to seek the sweet spot on the suspension of disbelief curve and avoid wasting resources that would only be dumped into the Uncanny Valley. In the case of VR Exposure Therapy applications I would suggest that the metaphor does double-duty and can also inform our selection of appropriate content to achieve reminiscence: we seek the sweet spot on the curve where we have included sufficient contextual details to evoke responses from a wide variety of patients without adding too much specific information that could distract from some patients? experiences.

How might we apply this? In our current design project we are making use of three rules of thumb to address the presence/reminiscence curve:

1)Favor the suggestive over the specific. When it is possible to imply a detail without actually filling it in then your design does not end up limited by that detail. In our next application we are planning to put action in shadows, use high dynamic range lighting and pixel shaders to create depth of field effects that will simultaneously draw focus in the scene and obscure background detail.

2)Use intentional ambiguity to cover a range of possible scenarios. We will attempt to design scenes that can be interpreted in a number of different ways. Are those two figures in the distance insurgents or allies? Is that a checkpoint ahead, or an ambush? Was an attacker just killed by shrapnel from an IED or did you just accidentally shoot a civilian? Many scenarios can look the same and mean different things in different contexts.

3)Use systemic designs and parallel information to specify and disambiguate. As we have seen, a single, carefully placed sound file can set the tone of a scene. Other types of sounds can pin down the meaning of the scene, and sounds play an extremely valuable roll in VR therapy for PTSD. Rather than spend resources on perfect individually tailored effects use generic ones that can be placed anywhere. Physics and materials can make a scenario flexible, and then small details delivered by the therapist can make the scene specific to the individual.

We have anecdotal evidence that this kind of design may be spectacularly successful specifically for Exposure Therapy applications. More than one researcher has reported(10) that VR Exposure therapy patients, when recalling their therapy experiences, have occasionally described significant components of their experience in VR that were not actually present in the simulation! It is as if, adjacent to the Uncanny Valley there is a peak where subjects will fill in major details from their own experiences and the simulation magically becomes more than real. PTSD patients carry around in their heads a set of special effects that we can?t ever match with simulation. With VR Exposure Therapy applications the key may be to design simulations that provide maximal space for the patient and the therapist to do their work.

As with entertainment applications, in VR Exposure Therapy, emotional engagement is critical to success. We have expanded upon Masahiro Mori?s robot realism curve in an attempt to synthesize some design guidelines for building VR Exposure Therapy applications. This presence/reminiscence curve may turn out to be a useful metaphor not only for designing the most compelling experiences, but also for modeling how a therapist interacts with the toolset to administer the therapy. The exposure therapy protocol calls for a gradual ramping up of the intensity of the simulation. A useful way of thinking about this is to imagine the therapist climbing the presence/reminiscence curve with the patient. Addressing the whole left side of the curve in our designs-- and not just the peak-- could be an excellent way to provide therapists with the smooth control they need.

We have used some fairly simple ideas here to provide a modicum of structure to an otherwise complex and under-constrained design process. It is our profound hope that the therapists who use the tools we build will have an easier time with their work. Now we await validation of these ideas from the therapy and research. It is an unusual and exciting situation for a software developer, where, if success comes, it will be not in the form of software sales, but in people healed.

Feb 4, 2009
What a great accomplishment this could be for our soldiers and others. What healing power it could possess. Thanks for interesting read mary.

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