RegionalSliding: Facilitating small target selection with marking menu for one-handed thumb use on touchscreen-based mobile devices.

Small target selection on mobile devices with touchscreens usually brings trouble to users due to the occlusion of the target by the user’s finger, as well as the ambiguity about which part of the finger generates the contact point. In this paper, we propose a novel technique to enhance target selection on touchscreen-based mobile devices, called RegionalSliding, which if necessary renders the initially selected target as well as its “surrounding” targets as a marking menu in a non-occluded area when users press down on the screen without lifting, and enables users to complete the selection with natural sliding gestures according to the visual feedback from the rendered area. We recognized the range of unintentional displacement and users’ sliding habits through two pilot studies, which indicated significant parameters of the marking menu for our design. We then conducted a user study that compared RegionalSliding with Shift (Vogel and Baudisch, 2007) and TapTap (Roudaut et al., 2008). Experimental results showed that RegionalSliding not only performed at the lowest mean error rate and at a shorter task completion time than Shift, but was also less affected by other factors, such as the target size, than the other two target selection techniques when acquiring small square targets.