EFFECTS OF TARGET SIZE ON FINGER CONTACT AREA IN TOUCHING THE INTERFACE OF APPLIANCES

This study focused on a physical property of human finger touch: finger contact area (FCA). The value of FCA lies not only in optimizing the interface layout design but also in streamlining the process of sensitivity tuning for capacitive devices. However, from previous research, whether the target size and display position have effects on the FCA is unknown, and the data of FCA in the contexts of touching various appliances had never been explored. A within-subjects experiment was conducted to study the FCA in the context of four target sizes and two display positions. Forty-two participants were recruited, and both their demographic data as well as touch data were collected and analyzed. As a result, both the target size and the display position have significant effects on the FCA size, and users would implement different finger approach angles (FAA) in varying contexts accordingly. In general, larger target size and vertical touch surface would lead to a larger FCA size, but other factors such as finger joint circumference, stature, touch force did not show significant effects in the experiment. Overall, this study contributes to a clearer understanding of FCA data as well as how users behave in the touch interaction on the capacitive touch interface of appliances. Moreover, it pointed out what factors were related or unrelated to the FCA. This knowledge would directly help designers and engineers to develop optimized capacitive buttons with appropriate sizes as well as sensitivity on touch interfaces of appliances and could improve the usability of the capacitive touch interface in the future.