How to Optimize the Input Efficiency of Keyboard Buttons in Large Smartphone? A Comparison of Curved Keyboard and Keyboard Area Size

Smartphone has been constantly optimizing the user experience of viewing content by increasing screen size. However, larger screen brings about unsatisfactory input issue, especially for one-handed users. Curved QWERTY keyboard and reduced soft keyboard area are proposed to solve the input inefficiency issue of application design in the large smartphones. Following the design of existing curved keyboards, we designed a keyboard application, which could collect all the usage data, to test whether the curved keyboard or reduced-area keyboard could indeed solve the input inefficiency issue. By using within-subject design. we compared 2 screen sizes (5.0 in. vs. 6.5 in.), 2 area sizes (small-area: letter key area is 4.9 mm × 7 mm vs. large-area: letter key area is 6.3 mm × 9 mm), and 2 keyboard layouts (curved QWERTY vs. traditional QWERTY). The results show that the large-area keyboard is significantly better in terms of pairs per minute and reaction time between two keys, at the same time, the curved keyboard performs worse than the traditional keyboard. It indicates that the two design elements are not a common practice.

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