Investigating the Potential of a Two-finger Chord Button in Multi-touch Applications

With the increasing use of multi-touch (MT) capable devices, MT interaction has become a commodity during the last years. From personal devices to larger multi-user screens, MT functionality is nowadays considered as a standard way of performing rich interactions. However, moving from a single-touch interaction to a dual-touch and consequently to MT is not always without challenges for the average user. Although, the use of single-touch is very common, interaction design have yet to be examined thoroughly by taking into account potential differences of single and multi-touch functionality. In this work, we investigate the potential of a two-finger chord button in comparison to the traditional single touch buttons that we find in touchscreens. Based on the fact that users are familiar with single touch buttons (even before the MT screens) our hypotheses are: the use of a two finger chord button a) decreases users' efficiency, and b) delays users' responses. In order to investigate our hypotheses, we conducted a controlled experiment with 12 users working on an appropriately designed MT application. The empirical results have indicated that the use of two-finger button significantly delays users' response-time while it does not affect users' efficiency on the performed task.