Full paper.
Touchscreens are among the most ubiquitous input technologies. Commercial devices typically limit the input to 2D touch points. While a body of work enhances the interaction through finger recognition and diverse gestures, advanced input techniques have had a limited commercial impact. A major challenge is explaining new input techniques to users. In this paper, we investigate how to communicate novel input techniques for smartphones. Through interviews with 12 UX experts, we identified three potential approaches:Depictionuses an icon to visualize the input technique, Pop-upshows a modal dialog when the input technique is available, and Tutorialexplains all available input techniques in a centralized way. To understand which approach is most preferred by users we conducted a study with 36 participants that introduced novel techniques using one of the communication methods. While Depictionwas preferred, we found that the approach should be selected based on the complexity of the interaction, novelty to the user, and the device size.