Evaluation of Non-visual Zooming Operations on Touchscreen Devices

The limited screen real estate of touchscreen devices necessitates the use of zooming operations for accessing graphical information such as maps. While these operations are intuitive for sighted individuals, they are difficult to perform for blind and visually-impaired (BVI) people using non-visual sensing with touchscreen-based interfaces. We address this vexing design issue by investigating the perceptual and cognitive factors involved in: (1) non-visual zooming operations, and (2) integrating information across multiple zoom levels to build a global cognitive map. A behavioral study compared map learning performance between two zoom-mode conditions and a no-zoom control. Results revealed that non-visual zooming operations are not only possible, but actually lead to improved efficiency of touch-based non-visual learning. Findings provide compelling evidence for the efficacy of incorporating zooming operations on touchscreen-based non-visual interfaces and have significant broader impacts for improving the accessibility of a wide range of graphical information for BVI people.