While text-to-speech software has largely made textual information accessible in the digital space, analogous access to graphics still remains an unsolved problem. Because of their portability and ubiquity, several studies have alluded to touchscreens as a potential platform for such access, yet there is still a gap in our understanding of multimodal information transfer in the context of graphics. The current research demonstrates feasibility for following lines, a fundamental graphical concept, via vibrations and sounds on commercial touchscreens. Two studies were run with 21 blind and visually impaired participants (N = 12; N = 9). The first study examined the presentation of straight, linear lines using a multitude of line representations, such as vibration-only, auditory-only, vibration lines with auditory borders, and auditory lines with vibration borders. The results of this study demonstrated that both auditory and vibratory bordered lines were optimal for precise tracing, although both vibration- and auditory-only lines were also sufficient for following, with minimal deviations. The second study examined the presentation of curving, non-linear lines. Conditions differed on the number of auditory reference points presented at the inflection and deflection points. Participants showed minimal deviation from the lines during tracing, performing nearly equally in both 1- and 3-point conditions. From these studies, we demonstrate that line following via multimodal feedback is possible on touchscreens, and we present guidelines for the presentation of such non-visual graphical concepts.
Tennison, J. L., & Gorlewicz, J. L. (2019). Non-visual Perception of Lines on a Multimodal Touchscreen Tablet. ACM Transactions on Applied Perception (TAP), 16(1), 6.