Analysis of Assets for Virtual Reality Applications in Neuropsychology Albert A. Rizzo, Maria Schultheis, Kimberly A. Kerns, and Catherine Mateer, Neuropsychological Rehabilitation (page 3 of 18) Page 3 of 18

This asset can be seen to allow for the hierarchical delivery of stimulus challenges across a range of difficulty levels. For example, an individual's rehabilitation could be customized to begin at a stimulus challenge level most attainable and comfortable for them, with gradual progression of difficulty level based on that individuals' performance. The rehabilitation of driving skills following traumatic brain injury is one example where individuals may begin at a simplistic level (i.e., straight, non-populated roads) and gradually move along to more challenging situations (i.e., crowded, highway roads) (Schultheis & Mourant, 2001). This asset would also provide the opportunity to identify, implement and modify individual compensatory strategies that can be tested at various hierarchical levels of challenge within a VE modeled after a targeted real world environment. Repeated practice could result in "successful learning" and produce positive reinforcement of compensatory strategy use that could potentially enhance the generalization of these strategies to everyday activities. As well, the successful execution of many everyday activities often requires the integration of a variety of cognitive functions, and subsequent component evaluation of these complex behaviors is often challenging to clinicians and researchers. By providing options for stimulus control within a VE, the impact of specific component cognitive assets and limitations may be better isolated, assessed and rehabilitated.

Enhanced stimulus control also can result in better consistency of stimulus presentations. Naturally occurring changes in "everyday" real world settings typically make the exact repetition of assessment unfeasible and this inconsistency can negatively impact on the standardization of defining and measuring specific behaviors. For example, current assessment and rehabilitation approaches of everyday functional skills, such as ambulation in the community, are currently limited by the inability to control and repeat exact stimuli in relevant settings (i.e., in the street, within office buildings). Subsequently, assessment and rehabilitation is typically conducted within a more controlled environment (e.g., gymnasium), which may not reflect the actual demands of ambulation in the "real world". The application of VR to this approach would address this limitation by allowing assessment and rehabilitation in more functionally relevant VEs (e.g., city streets) while still allowing clinicians and researchers full control over stimulus presentations. This level of control could serve to improve consistency across assessments and interventions and allow for increased standardization and validation of methods for assessing complex behaviors. Examples of such VR applications include the development of "virtual cities" and other complex environments for assessing and rehabilitating wayfinding (Brown, Kerr & Bayon, 1998), the use of public transportation (Mowafty & Pollack, 1995) and a wide range of other instrumental activities of daily living (see review in Rizzo et al, 2002a).

2. The capacity to create of more ecologically valid assessment and rehabilitation scenarios.

Traditional NP assessment and rehabilitation has been criticized as limited in the area of ecological validity, that is, the degree of relevance or similarity that a test or training system has relative to the "real" world (Neisser, 1978). While existing NP tests obviously measure behaviors mediated by the brain, controversy exists as to how performance on analog tasks relates to complex performance in an "everyday" functional environment. By designing virtual environments that not only "look like" the real world, but actually incorporate challenges that require 'real world' functional behaviors, the ecological validity of cognitive/functional performance assessment and rehabilitation could be enhanced. As well, the complexity of stimulus challenges found in naturalistic settings could be presented while still maintaining the experimental control required for rigorous scientific analysis and replication. Thus, VR derived assessment results could have greater predictive validity/clinical relevance and a more direct linkage to both restorative and functional NP rehabilitation approaches.

A number of examples illustrate efforts to enhance the ecological validity of assessment and rehabilitation by designing VEs that are "replicas" of relevant archetypic functional environments. This has included the creation of virtual cities (Brown et al., 1998; Costas, Carvalho & de Aragon, 2000), supermarkets (Cromby et al., 1996); homes (Rose et al., 2001); kitchens (Christiansen et al., 1998; Davies et al., 1998;), school environments (Stanton et al., 1998; Rizzo et al., 2000), workspaces/offices (McGeorge et al., 2001; Schultheis & Rizzo, 2002); rehabilitation wards (Brooks et al., 1999) and even a virtual beach (Elkind et al., 2001). While these environments vary in their level of pictorial or graphic realism, this factor may be secondary in importance, relative to the actual activities that are carried out in the environment for determining their value from an ecological validity standpoint. Interestingly, when in a virtual environment, humans often times display a high capacity to "suspend disbelief" and respond as if the scenario was real. It could be conjectured that the "ecological value" of a VR task that needs to be performed may be well supported in spite of limited graphic realism and less immersion (such as in flatscreen systems). In essence, as long as the VR scenario "resembles" the real world, possesses design elements that replicate key real life challenges and the system responds well to user interaction, then ecological validity is enhanced beyond existing analog approaches. Evidence to support this view can be drawn from clinical VR applications that address anxiety disorders. While a number of the successful VR scenarios designed for exposure-based therapy of specific phobias would never be mistaken for the real world, clients within these VEs still manifest physiological responses and report subjective units of discomfort levels that suggest they are responding "as if" they are in the presence of the feared stimuli (Wiederhold & Wiederhold, 1998).

From Neuropsychological Rehabilitation, 2004. 14(1/2), 207-239. Reprinted with permission from Albert Rizzo. All rights reserved.

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