Target and spacing sizes for smartphone user interfaces for older adults : design patterns based on an evaluation with users

The use of smartphones is becoming widespread among all sectors of the population. However, developers and designers do not have access to guidance in designing for specific audiences such as older adults. This study investigated optimal target sizes, and spacing sizes between targets, for smartphones user interfaces intended for older adults. Two independent variables were studied — target sizes and spacing between targets — for two common smartphone gestures — tap and swipe. Dependent variables were accuracy rates, task completion times, and participants’ subjective preferences. 40 older adults recruited from several daycare centers participated in both tasks and a post-session questionnaire. The recommendations drawn from the authors’ research support two interaction design patterns relative to touch target sizes for older adults, and are presented in this paper.