Tilt-Explore: Making Tilt Gestures Usable for Low-Vision Smartphone Users

People with low vision interact with smartphones using assistive technologies like screen magnifiers, which provide built-in touch gestures to pan and zoom onscreen content. These gestures are often cumbersome and require bimanual interaction. Of particular interest is panning gestures, which are issued frequently, which involve 2- or 3-finger dragging. This paper aims to utilize tilt-based interaction as a single-handed alternative to built-in panning gestures. To that end, we first identified our design space from the literature and conducted an exploratory user study with 12 low-vision participants to understand key challenges. Among many findings, the study revealed that built-in panning gestures are error-prone, and most tilt-based interaction techniques are designed for sighted users, which low vision users struggle to use as-is. We addressed these challenges by adapting low-vision users' interaction behavior and proposed Tilt-Explore, a new screen magnifier mode that enables tilt-to-pan. A second study with 16 low-vision participants revealed that, compared to built-in gestures, the participants were significantly less error-prone; and for lower magnification scale (e.g., <4x), they were significantly more efficient with Tilt-Explore. These findings indicate Tilt-Explore is a promising alternative to built-in panning gestures.