Use of Scaling to Improve Reach in Virtual Reality for People with Parkinson's Disease

This research investigates the effect of scaling in virtual reality to improve the reach of users with Parkinson's disease (PD). People with PD have limited reach, often due to impaired postural stability. We investigated how virtual reality (VR) can improve reach during and after VR exposure. Participants played a VR game where they smashed water balloons thrown at them by crossing their midsection. The distance the balloons were thrown at increased and decreased based on success or failure. Their perception of the distance and their hand were scaled in three counterbalanced conditions: under-scaled (scale = 0.83), not-scaled (scale = 1), and over-scaled (scale = 1.2), where the scale value is the ratio between the virtual reach that they perceive in the virtual environment (VE) and their actual reach. In each study condition, six data were measured −1. Real World Reach (pre-exposure), 2. Virtual Reality Baseline Reach, 3. Virtual Reality Not-Scaled Reach, 4. Under-Scaled Reach, 5. Over-Scaled Reach, and 6. Real World Reach (post-exposure). Our results show that scaling a person's movement in virtual reality can help improve reach. Therefore, we recommend including a scaling factor in VR games for people with Parkinson's disease.