Analyzing thumb interaction on mobile touchpad devices

A touchpad is a convenient device component on account of its mobility and portability, and is used more widely nowadays to control various devices. This study investigated the usability of a touchpad when subjects performed the task of pressing a target on a mobile device. The 3.5-inch mobile device was used in an experiment in which the subject pressed a single target. A total of 24 right-handed subjects participated in the experiment. The breadth and length of the thumb of each subject were measured. Task performance times and the number of errors were analyzed. The results showed that task performance times increased as the target size decreased and that the target location was in the lower-right corner. In terms of the length of the thumb, the group of the longest thumb had the lowest performance. The results of this study can be used to design touchpad-related interfaces using thumb-based control for other mobile devices. Relevance to industry: The results of this study are expected to be useful in the development of a mobile interface that considers the specific features of the user's thumb.