The effects of touch screen virtual keyboard key sizes on typing performance, typing biomechanics and muscle activity

Abstract

The goal of the present study was to determine whether different touch screen virtual keyboard key sizes affected typing productivity, typing forces, and muscle activity. In a repeated-measures laboratory experiment with 21 subjects, typing speed, accuracy, muscle activity, and typing forces were measured and compared between four different key sizes: 13x13, 16x16, 19x19, and 22x22 mm. The results showed that 13 mm keyboard had a 15% slower typing speed (p < 0.0001) and slightly higher static (10th %tile) shoulder muscle activity (2%, p = 0.01) as compared to the other keyboards with larger keys. The slower typing speed and slightly higher shoulder muscle activity indicated that 13 mm keyboard may be less optimal for touch typing compared to the larger key sizes. © 2013 Springer-Verlag.