OBJECTIVE: We examined the usability issues associated with four touch screen gestures (clicking, dragging, zooming, and rotating) among older and younger users. BACKGROUND: It is especially important to accommodate older users' characteristics to ensure the accessibility of information and services that are important to their quality of life. METHOD: Forty older and 40 younger participants completed four experiments, each of which focused on one gesture. The effects of age, type of touch screen (surface acoustic wave vs. optical), inclination angle (30°, 45°, 60°, and 75°), and user interface factors (clicking: button size and spacing; dragging: dragging direction and distance; zooming: design of zooming gesture; rotating: design of rotating gesture) on user performance and satisfaction were examined. RESULTS: Button sizes that are larger than 15.9 × 9.0 mm led to better performance and higher satisfaction. The effect of spacing was significant only when the button size was notably small or large. Rightward and downward dragging were preferred to leftward and upward dragging, respectively. The younger participants favored direct manipulation gestures using multiple fingers, whereas the older participants preferred the click-to design. The older participants working with large inclination angles of 60° to 75° reported a higher level of satisfaction than the older participants working with smaller angles. CONCLUSION: We proposed a set of design guidelines for touch screen user interfaces and discussed implications for the selection of appropriate technology and the configuration of the workspace. APPLICATION: The implications are useful for the design of large touch screen applications, such as desktop computers, information kiosks, and health care support systems.
OBJECTIVE: We examined the usability issues associated with four touch screen gestures (clicking, dragging, zooming, and rotating) among older and younger users. BACKGROUND: It is especially important to accommodate older users' characteristics to ensure the accessibility of information and services that are important to their quality of life. METHOD: Forty older and 40 younger participants completed four experiments, each of which focused on one gesture. The effects of age, type of touch screen (surface acoustic wave vs. optical), inclination angle (30°, 45°, 60°, and 75°), and user interface factors (clicking: button size and spacing; dragging: dragging direction and distance; zooming: design of zooming gesture; rotating: design of rotating gesture) on user performance and satisfaction were examined. RESULTS: Button sizes that are larger than 15.9 × 9.0 mm led to better performance and higher satisfaction. The effect of spacing was significant only when the button size was notably small or large. Rightward and downward dragging were preferred to leftward and upward dragging, respectively. The younger participants favored direct manipulation gestures using multiple fingers, whereas the older participants preferred the click-to design. The older participants working with large inclination angles of 60° to 75° reported a higher level of satisfaction than the older participants working with smaller angles. CONCLUSION: We proposed a set of design guidelines for touch screen user interfaces and discussed implications for the selection of appropriate technology and the configuration of the workspace. APPLICATION: The implications are useful for the design of large touch screen applications, such as desktop computers, information kiosks, and health care support systems.