Heading assessment by “tunnel vision” patients and control subjects standing or walking in a virtual reality environment

Abstract

Virtual reality locomotion simulators are a promising tool for evaluating the effectiveness of vision aids to mobility for people with low vision. This study examined two factors to gain insight into the verisimilitude requirements of the test environment: the effects of treadmill walking and the suitability of using controls as surrogate patients. Ten "tunnel vision" patients with retinitis pigmentosa (RP) were tasked with identifying which side of a clearly visible obstacle their heading through the virtual environment would lead them, and were scored both on accuracy and on their distance from the obstacle when they responded. They were tested both while walking on a treadmill and while standing, as they viewed a scene representing progress through a shopping mall. Control subjects, each wearing a head-mounted field restriction to simulate the vision of a paired patient, were also tested. At wide angles of approach, controls and patients performed with a comparably high degree of accuracy, and made their choices at comparable distances from the obstacle. At narrow angles of approach, patients' accuracy increased when walking, while controls' accuracy decreased. When walking, both patients and controls delayed their decisions until closer to the obstacle. We conclude that a head-mounted field restriction is not sufficient for simulating tunnel vision, but that the improved performance observed for walking compared to standing suggests that a walking interface (such as a treadmill) may be essential for eliciting natural perceptually-guided behavior in virtual reality locomotion simulators.

Comparison of Visual Parameters Between Normal Individuals and People with Low Vision in a Virtual Environment

“…Magnusson et al, Papageorgiou et al, Apfelbaum et al, [19][20][21][22][23] and several other authors have studied the performance and response of visually impaired subjects in a virtual environment and have shown the validity of VR in various aspects such as way-finding tasks, collision avoidance, exploration, and so on. However, the use of VR scenario for assessing navigation tasks in case of visual impairment has its limitations, and it becomes difficult to compare the deficits seen in the VR world and real world.…”

P-27: Maintaining Position and Display Perspective in a Walking Simulator while Self-Pacing on a Treadmill

“…To avoid the high cost of the Sarcos Treadport system, others have used cheaper, smaller, conventional treadmills, moving at fixed speeds [2,6]. Apfelbaum et al [1] placed a bar in front of the subject to keep their position constant. This approach does keep the visual extents of the screen constant, but it does not allow the user to set and vary their walking speed naturally and an incorrectly chosen treadmill speed may cause fatigue.…”

“…The self-propelled treadmill mode does keep the visual extent constant and allow the subject to adjust their walking speed. In such a configuration, the treadmill motor is disengaged and the subjects move the treads while pushing front handrails or are tied to ropes behind them [1,5,13,16]. While this may be acceptable for younger, physically fit subjects, older or less-fit subjects may have difficulty with the level of exertion required to push the tread for the duration of an experiment.…”

ScreenMasker: An Open-source Gaze-contingent Screen Masking Environment

“…In addition, gaze-contingent systems facilitated the research into the impact of simulated visual field defects on the heading task performance (Cornelissen & van den Dobbelsteen, 1999), on human walking in virtual environments (Apfelbaum et al, 2007), and on visual search (Cornelissen et al, 2005).…”