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Immersive Rehearsal in a Simulated Environment.

INTRODUCTION
Recent advancements in virtual environment (VE) technology and the increasing use of VEs for treatment are opening up possibilities for rehearsal in safe and rich environments. Research has shown that VEs can be used to treat individuals with posttraumatic stress disorder (PTSD), but little research has been done to suggest guidelines for creating an effective environment. The aim of this study was to determine the design of systems that would allow military veterans to rehearse potentially stressful events in a VE before having to step into the actual environment. This research evaluated the responses to six stimuli: startle sound, direct eye contact, horizontal movement across the visual field, social conflict, an abandoned item, and a crowded auditorium. Measures used included change in heart rate (ΔHR), change in subjective unit of discomfort scores, and participant behavior.


MATERIALS AND METHODS
Thirty-eight participants, both with and without PTSD, experienced two VEs in first person using an Oculus Rift device. The first VE consisted of a tranquil garden, which allowed the participants to practice in the system, whereas baseline data were collected. The second VE was the experimental condition where the participant completed tasks within the VE and encountered stimuli designed to evoke responses from those with PTSD.


RESULTS
There was a significant difference in ΔHR between the PTSD and non-PTSD groups (P = .008), and the PTSD group had a higher mean ΔHR for all stimuli. The stimulus type was also significant for all participants (P < .001). Crowded auditorium and startle sound had the largest impact on the participants' ΔHR. Change in subjective unit of discomfort showed a significant interaction between the group factor (PTSD, non-PTSD) and stimulus (P = .043). Individuals with PTSD also presented more avoidance behavior than those without PTSD.


CONCLUSIONS
Findings imply that VEs other than virtual combat zones can elicit behavioral, emotional, and physiological responses in individuals with PTSD, and these types of environments should be further studied for use with veterans suffering from PTSD. In future studies, systems should include initial stimuli that can be configured to allow focus on specific past traumatic experiences. Stimuli should also include both a crowded room and a startle noise scenario.