Effect of Button Size and Location When Pointing with Index Finger on Smartwatch

Users control smartwatches through touch screen interfaces such as smartphones. However, because smartwatches are very small and users’ postures differ depending on the device, control using touch screens needs to be adapted for smartwatches. Users tap buttons on the touch screen to control the smartwatch, so speed and accuracy of button input are required. Users’ button input speed and accuracy are affected by displayed button size and location. In this study, we investigated the effects of button size and location when pointing with the index finger on a smartwatch. The results suggest that the pointing error rate is significantly affected by button size and location. The error rates became lower as the buttons became larger and when the buttons were located near the center of the screen.