Impact of button position and touchscreen font size on healthcare device operation by older adults

In 1993, Taiwan officially became an aging society. Degradation of physiological function during aging is inevitable; visual and physical reactions are especially vulnerable. Given the popularity of electronic devices and their vigorous development in recent years, touchscreen use is now commonplace. As society ages, many people use devices to monitor their health. Some products have gradually eschewed their traditional interfaces, which have been replaced by touchscreens. Touchscreen operation and interpretation differ between older and younger populations. Here, we focus on healthcare equipment, exploring the effects of button position and touchscreen font size on operation by older people. To understand differences between older and younger people, we invited 32 people aged 18-35 years, and 32 people aged over 65 years, to participate in our experiment. Each subject tested four button positions and four font sizes, thus 16 test interfaces in all. We found that young people found no differences among the 16 interfaces, but the older group did. Larger fonts reduced operation time for older participants. At a font size of 22 pt, the older group performed as well as the young participants. When buttons were positioned at the top of the interface, the performance of the older participants improved. Overall, use of a font size of 22 pt and top-positioned buttons optimized the performance of the older participants while use of a font size of 10 pt and bottom-positioned buttons maximally degraded their performance. Our results can be used to design interfaces appropriate for older people, thus improving their autonomy.