Assessing touchscreen operations under vibration: effects of vibrational environments, button size, and button spacing on digit- and letter-entry task performance

Touchscreen interfaces are increasingly used in vibration contexts. However, little is known about how they should be designed to cope with vibrations. This study aimed to examine the effects of button size and button spacing on entry performance in varied vibrational environments. Twenty participants were instructed to perform a series of digit- and letter-entry tasks with a touchscreen interface. Vibrational environments (static, low vibration, and high vibration), button sizes (7.5–27.5 mm with 5-mm increments), and button spacings (0, 1, and 3 mm) were factorially combined. Increased vibration level was associated with increased time to complete task, lower accuracy rate, higher perceived workload, and increased perceived discomfort. User performance improved as button size increased up to 17.5 mm. A button spacing of 1 mm was favorable in terms of entry efficiency. The detrimental effects of vibration on information entry performance and users’ perceptions were observed. The results indicated that touchscreen interfaces should be carefully designed to cater for use in vibrational environments. Favorable button size and button spacing to deal with vibrational environments were identified.