A Study on the Usability of Typing Interface on Large-Screen Phones for Different Thumb Sizes

Abstract

Currently, the larger-screen phone has gradually replaced the small screen mobile phone that has been unable to meet the needs of long-term reading. However, there is hardly any one-handed use for actually touching the larger-screen, making one-handed operation (using the thumb operation) more difficult; in particular, users with short thumbs may suffer an uncomfortable experience in its use. The participants' typing gestures were then observed when using their phones in a natural manner. Finally, the participants were asked use one thumb with extended, natural and bending gestures, respectively, to slide on a specified typing screen, and the sizes of these three sliding areas, named Stretch, Natural and OW, were measured to find the suitable typing area for different hand sizes. The results of this study found that the typing gestures could be classified into four types: One-Handed (15.6%), Two-Handed (68.8%), Hold & Tap, (6.3%) and Cradle (9.4%). Moreover, the Natural and OW areas for the larger and middle hands were both bigger than the one for the small hand, while there were no significant differences between the larger and middle hands. this indicated that the length of the thumb would affect the usability of the phone. These results can provide a reference for the interface designer.