The Right Fit: Optimizing Usability with Handedness-Adaptive Smartphone Interfaces

Abstract

This research investigates the impact of a handedness-adaptive smartphone interface on usability. A considerable amount of research has been conducted towards smartphone interfaces, but many of these only consider right-handed users. Since poor usability can contribute to musculoskeletal disorders and carpal tunnel syndrome, improving smart- phone interfaces is essential. Handedness-adaptive designs offer a promising solution to enhance usability for a broader range of users, left-handed users in particular. To study this, a within subject quantitative experiment was conduc- ted with 135 participants where two interfaces were compared: a standard interface that places elements within the reachable areas of right-handed users, and a mirrored interface that places the elements within the reachable areas of left-handed users. Each participant performed twelve tasks four times, once for each interface in combination with both their left and right hand. After all four twelve task iterations, the participants filled out a user experience test. The usability of each task was measured using the three usability dimensions: accuracy (path measures and distance), speed (task action duration and total time), and user experience (satisfaction rate). The analysis showed a significantly higher usability for the handedness-adaptive smartphone interfaces, mainly for the distance, duration and satisfaction rate measurements. Additionally, flick and drag tasks showed that flicks should be performed toward the center of the screen and horizontal drags should not start too close to the hand. It was concluded that handedness-adaptive smartphone interfaces improve usability.