Touch key design for target selection on a mobile phone

Abstract

Mobile phones with a touch screen replacing traditional keypads have been introduced to the market. Few studies, however, have been conducted on the touch interface design for a mobile phone. This study investigated the effects of touch key sizes and locations on the one-handed thumb input that is popular in mobile phone interactions. Three different touch key sizes (i.e. square shape with 4mm, 7mm, and 10mm wide) and twenty five locations were examined in an experiment. The results provided two groups of touch key locations (an appropriate and an inappropriate region) with respect to three usability measures including success rate, number of errors, and pressing convenience. In addition, a hits distributions based algorithm was applied to target selection tasks, which statistically improved the performance. The results of this study could be used to design touch keys so as to enhance the usability of mobile phones with a touch screen.

User interface design guidelines for smartphone applications for people with Parkinson’s disease

“…However, their study setup included a fixed tablet in a specific angle, which is quite different from the normal usage of a smartphone. These target sizes contrast with the 9-10mm suggested by other studies [40,41]. A more recent study [26] reported that older adults have the best accuracy when tap targets on the smartphone have between 14 and 17.5mm, with 10mm being acceptable when screen space is restricted.…”

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“…But, we do not want all items of the same hierarchy level to be visible, so, as ERELT [7], we display only a part of items and user can access hidden ones by dragging them on the active view. This design allows us to make all items the same size (Figure 7), which can fit through tactile guidelines [18], and not to limit the broadness of hierarchy datasets.…”