Effects of Grip Curvature and Size of Hand on Comfort for the Unimanual Operation of Handheld Touchscreen Device

This study aims to investigate the effect of size of a hand and curvature of handheld touchscreen devices on comfort when unimanually using the devices. By rated subjectively and recording EMG, comfort was measured for the use of three mock-ups of the device with different curvatures; one had flat surface and the others had curvatures of 400R and 100R for each. During the experiment, tapping, typing and dragging tasks were performed and the participants evaluated comfort subjectively and objectively. A difference among curvatures was analyzed as well as a difference among participant groups classified by size of their preferred hand. The results indicated that curvature of the handheld touchscreen devices affected neither muscle activities nor subjective comfort level. Moreover, size of hand was found to affect comfort objectively measured, but not the one subjectively rated. Overall, this study suggests that comfort measured subjectively does not consistent with comfort measured by objective data. Also, users’ hand size may be more critical factor than curvature of handheld touchscreen determining comfort of touch screen use.