Balance with the interactive size effects of display, target, and key spacing in tablet tapping, dragging, and typing tasks

Abstract

This study aimed to expand the current demonstration of display size effects from pointing tasks to dragging and tap‐typing tasks to investigate the effects of influential factors on the performance of touchscreen tablets. From 7‐ to 11‐in. displays, the index of difficulty was kept constant by increasing the target amplitudes and widths (6.0–9.5 mm) proportionally, and the key spacing were, respectively, 13.5 × 7.3–21.5 × 11.5 mm with 0‐mm key gaps. The results demonstrated that simple task types (complexities) reinforced the display size effects and that the effects interacted with target sizes (including amplitude/width scaling) and key spacing to reflect increasing efficiency and usability with increasing sizes. Gender effects were only significant in subjective assessments. Display sizes approaching 10 in., target sizes not less than 7 mm (optimal 9–10 mm) and key spacing larger than 17.5 mm induced the effects of motor scale (the scale of the upper limb joint coordination) and interacted with one another to result in the optimal performance and usability.