Design Guidelines for Schematizing and Rendering Haptically Perceivable Graphical Elements on Touchscreen Devices

• Published in: International journal of human-computer interaction Vol. 36; no. 15; pp. 1393 - 1414
• Main Authors: Palani, Hari P., Fink, Paul D. S., Giudice, Nicholas A.
• Format: Journal Article
• Language: English
• Published: Norwood Taylor & Francis 13-09-2020; Lawrence Erlbaum Associates, Inc
• Subjects: Cognition; Design; Eye (anatomy); Guidelines; Haptics; Information dissemination; Information retrieval; Interactive computer systems; Intersections; Parameters; Rendering; Touch screens
• ISSN: 1044-7318; 1532-7590; 1044-7318
• DOI: 10.1080/10447318.2020.1752464

This paper explores the viability of new touchscreen-based haptic/vibrotactile interactions as a primary modality for perceiving visual graphical elements in eyes-free situations. For touchscreen-based haptic information extraction to be both accurate and meaningful, the onscreen graphical elements should be schematized and downsampled to: (1) maximize the perceptual specificity of touch-based sensing and (2) account for the technical characteristics of touchscreen interfaces. To this end, six human behavioral studies were conducted with 64 blind and 105 blindfolded-sighted participants. Experiments 1-3 evaluated three key rendering parameters that are necessary for supporting touchscreen-based vibrotactile perception of graphical information, with results providing empirical guidance on both minimally detectable and functionally discriminable line widths, inter-line spacing, and angular separation that should be maintained. Experiments 4-6 evaluated perceptually-motivated design guidelines governing visual-to-vibrotactile schematization required for tasks involving information extraction, learning, and cognition of multi-line paths (e.g., transit-maps and corridor-intersections), with results providing clear guidance as to the stimulus parameters maximizing accuracy and temporal performance. The six empirically-validated guidelines presented here, based on results from 169 participants, provide designers and content providers with much-needed guidance on effectively incorporating perceptually-salient touchscreen-based haptic feedback as a primary interaction style for interfaces supporting nonvisual and eyes-free information access.