Evaluation of key shapes on a touchscreen simulation of a specialised keypad

The effect of key shape on a touchscreen simulation of a flat touch-sensitive keypad was investigated by rapid prototyping. A software prototype was developed of a hardware keypad that controlled chemical analysis equipment. The prototype was used to answer some basic ergonomics questions concerning the design of the device keys. In a target selection task, keys shaped as equilateral triangles were most precise, and least precise was a compound shape comprising of a rectangular lower part and a triangular 'hat' as the upper part. No significant differences in the times taken to complete the task were found. It is suggested that the use of a touchscreen prototype is suitable when designing flat-keypad layouts. Due to the visual nature of flat keypad use, where perception of the target must counter reduced tactile feedback, the design of shapes to aid the selection of keys is of paramount importance. It is concluded that rapid prototyping of hardware with graphical designs and touchscreens is a powerful tool for the ergonomic design of interfaces.