Effect of Screen Switching and Brightness on Visual Fatigue in AR Environments

Augmented reality (AR) is being used increasingly in a number of domains for task assistance. Evolving augmented reality solutions may require more than one display screen in certain scenarios. Switching between the display screens repeatedly, in order to gather information, would thus be required in such AR environments. Repeatedly switching between the display screens will require the users to change their attention continuously. Additionally, the eye lens will have to accommodate at different distances when viewing the information presented on multiple display screens. These repeated accommodation demands, to change the focus of the eye lens, will put additional strain on the accommodation mechanism of the eye, thereby increasing visual fatigue. Attention switching and increased accommodation demands will eventually affect human performance. The human visual system will also be affected by the amount of light it is exposed to. It is understandable that the brightness of the display in an AR environment with respect to the ambient light would affect the visual fatigue induced in the users and eventually impact their performance. This study was aimed at studying the effect of repeated eye lens accommodation, attention switching and display screen brightness on human performance and visual fatigue, under typical illumination conditions. It was observed that medium brightness level induced least visual fatigue and resulted in highest performance levels in a room well lit by LED luminaries. Repeated eye lens accommodation and attention switching, involved in screen switching, were found to induce visual fatigue and adversely affect human performance.