Pixelated Interactions: Exploring Pixel Art for Graphical Primitives on a Pin Array Tactile Display

Two-dimensional pin array displays enable access to tactile graphics that are important for the education of students with visual impairments. Due to their prohibitive cost and limited access, there is limited research within HCI and the rules to design graphics on these low-resolution tactile displays are unclear. In this paper, eight tactile readers with visual impairments qualitatively evaluate the implementation of Pixel Art to create tactile graphical primitives on a pin array display. Every pin of the pin array is assumed to be a pixel on a pixel grid. Our findings suggest that Pixel Art tactile graphics on a pin array are clear and comprehensible to tactile readers, positively confirming its use to design basic tactile shapes and line segments. The guidelines provide a consistent framework to create tactile media which implies that they can be used to downsize basic shapes for refreshable pin-array displays.

1 INTRODUCTION Teaching practices for students with visual impairments rely on tactile graphics to make images, diagrams, maps, and art accessible. These are simplifed translations of visual images that are readable by the tactile sense [49]. For intelligible information, the Braille Authority of North America (BANA) provides guidelines for printed tactile graphics [50], but they do not extend to tactile graphics on refreshable pin array type tactile displays. Pin array displays are the refreshable tactile displays on which, tactile information is presented through an array of evenly spaced pins or tactile pixels that selectively pop out above a fat surface to create a tactile bump. Tactile graphics and shapes on these devices are hence created with a series of tactile dots, rather than continuous lines of printed interfaces. Among the many surface haptic technologies, pin array displays are the closest in terms of their haptic feedback to printed tactile media [29]. There are now a growing number of interactive pin-array displays, and these devices are highly aspirational among students, teachers and professionals who are visually impaired [35]. As technology develops, it is important to have guidelines to ensure repeatability, usability and scalability of information that is presented on the display [51]. Guidelines support an open innovation approach, which has been recommended to scale assistive technology [18]. This is especially important in low-resource environments (LREs) where education resources are severely limited for students with visual impairments, contributing to poor overall educational outcomes [8]. The educational losses compound over a lifetime, restricting the livelihood opportunities of people with visual impairments [14]. Within LREs, digital technologies, such as mobile phones, have bucked the trend of poor technology adoption [21], allowing people with disabilities increased independence and social participation [31]. However, advanced digital interactions, such as pin array displays, have been designed for and with people with visual impairments in high-resource settings. The resulting technologies remain prohibitively expensive for most people with visual impairments globally – a vast majority of whom live in LREs. The exception is Tacilia.