Handwriting on Touch Screens through Fingers and Stylus: Investigating the Optimal Size of the Input Box for Younger and Older Adults

Handwriting is widely used by Chinese older adults for text input on touch screens, but their handwriting performance is relatively low in comparison to younger adults. Therefore, this study investigated how the size of the input box (15%, 30%, and 45% of the display), input method (fingers and stylus), display size (4.7 inches and 7.9 inches), and age (younger adults and older adults) influence Chinese handwriting performance and user experience. An experiment was conducted among 72 participants. A system was developed to automatically record the time of handwriting, the accuracy of handwriting, the number of protruding strokes, the number of rewritings. Besides, participants' satisfaction, preferences, and mental workload were measured through questionnaires. The results revealed significant effects of the size of the input box, age, input method, and display size on the performance indexes and subjective ratings. Accordingly, 12 design implications for improving the Chinese handwriting system were identified.