Appropriate size, spacing, expansion ratio, and location for clickable elements on smart TVs with remote motion control

Motion control based on gyroscopes and/or accelerometers is a promising technique that can replace a typical television (TV) remote control. In this study, we investigated the effects of the size, spacing, expansion ratio, and location of clickable elements on the usability of remote motion control for smart TVs. Seven different target sizes, four expansion ratios, and 25 locations on a TV were examined in an experiment. Twenty-four people performed the task of pointing at and clicking on a single target on the TV with remote motion control. The results revealed that the target size of 80 mm exhibited the best performance in terms of the task completion time, pointing errors, and pointing convenience. A larger expansion ratio was better, particularly when the target size was smaller than 80 mm. Further, the usability of target locations was statistically analyzed. Then, the usability of 12 numeric keypads consisting of four different spacings among buttons and three button sizes were examined in another experiment. The results showed that a larger spacing among the buttons was worse, but the spacing of 10 mm was suitable for reducing errors with appropriate task completion time.