Thumbs-Up: 3D Spatial Thumb-Reachable Space for One-Handed Thumb Interaction on Smartphones

Abstract

People very often use mobile devices with one hand to free the second hand for other tasks. In such cases, the thumb of the hand holding the device is the only available input finger, making multi-touch interactions impossible. Complicating interaction further, the screen area that can be reached with the thumb while holding the device is limited, which makes distant on-screen areas inaccessible. Motivated by emerging portable object tracking technologies, we explore how spatial mid-air thumb-gestures could potentially be used in combination with on-screen touch input to facilitate one-handed interaction. From a user study we identify the 3D thumb-reachable space when holding a smartphone. We call this space "Thumbs-Up". This space extends up to 74 mm above the screen, making it possible to create interactions for the thumb of the hand holding the smartphone. We furthermore demonstrate how such Thumbs-Up techniques, when combined with on-screen interaction, can extend the input vocabulary in one-handed situations.