RESUMEN
The present study investigated whether there were physical exposure and typing productivity differences between a virtual keyboard with no tactile feedback and two conventional keyboards where key travel and tactile feedback are provided by mechanical switches under the keys. The key size and layout were same across all the keyboards. Typing forces; finger and shoulder muscle activity; self-reported comfort; and typing productivity were measured from 19 subjects while typing on a virtual (0 mm key travel), notebook (1.8 mm key travel), and desktop keyboard (4 mm key travel). When typing on the virtual keyboard, subjects typed with less force (p's < 0.0001) and had lower finger flexor/extensor muscle activity (p's < 0.05). However, the lower typing forces and finger muscle activity came at the expense of a 60% reduction in typing productivity (p < 0.0001), decreased self-reported comfort (p's < 0.0001), and a trend indicating an increase in shoulder muscle activity (p's < 0.10). Therefore, for long typing sessions or when typing productivity is at a premium, conventional keyboards with tactile feedback may be more suitable interface.