Comparing Graphical Pattern Matching on Tablets and Phones: Large Screens are Not Necessarily Better.
Touchscreen-based smart devices, such as smartphones and tablets, offer great promise for providing blind and visually-impaired (BVI) users with a means for accessing graphics non-visually. However, they also offer novel challenges as they were primarily developed for use as a visual interface. This paper studies key usability parameters governing accurate rendering of haptically-perceivable graphical materials. Three psychophysically-motivated usability studies, incorporating 46 BVI participants, were conducted that identified three key parameters for accurate rendering of vibrotactile lines. Results suggested that the best performance and greatest perceptual salience is obtained with vibrotactile feedback based on: (1) a minimum width of 1mm for detecting lines, (2) a minimum gap of 4mm for discriminating lines rendered parallel to each other, and (3) a minimum angular separation (i.e., cord length) of 4mm for discriminating oriented lines. Findings provide foundational guidelines for converting/rendering visual graphical materials on touchscreen-based interfaces for supporting haptic/vibrotactile information access.
Citation: Tennison, J.L., Carril, Z.S., Giudice, N.A., and Gorlewicz, J.L. (in press). Comparing Graphical Pattern Matching on Tablets and Phones: Large Screens are Not Necessarily Better. Optometry and Vision Science.