Effect of sitting or standing on touch screen performance and touch characteristics.

Objective: The aim of this study was to evaluate the effect of sitting and standing on performance and touch characteristics during a digit entry touch screen task in individuals with and without motor-control disabilities.

Background: Previously, researchers of touch screen design have not considered the effect of posture (sitting vs. standing) on touch screen performance (accuracy and timing) and touch characteristics (force and impulse).

Method: Participants with motor-control disabilities (n = 15) and without (n = 15) completed a four-digit touch screen number entry task in both sitting and standing postures. Button sizes varied from 10 mm to 30 mm (5-mm increments), and button gap was 3 mm or 5 mm.

Results: Participants had more misses and took longer to complete the task during standing for smaller button sizes (< 20 mm). At larger button sizes, performance was similar for both sitting and standing. In general, misses, time to complete task, and touch characteristics were increased for standing. Although disability affected performance (misses and timing), similar trends were observed for both groups across posture and button size.

Conclusion: Standing affects performance at smaller button sizes (< 20 mm). For participants with and without motor-control disabilities, standing led to greater exerted force and impulse.

Application: Along with interface design considerations, environmental conditions should also be considered to improve touch screen accessibility and usability.