Ripples: utilizing per-contact visualizations to improve user interaction with touch displays

We present Ripples, a system which enables visualizations around each contact point on a touch display and, through these visualizations, provides feedback to the user about successes and errors of their touch interactions. Our visualization system is engineered to be overlaid on top of existing applications without requiring the applications to be modified in any way, and functions independently of the application's responses to user input. Ripples reduces the fundamental problem of ambiguity of feedback when an action results in an unexpected behaviour. This ambiguity can be caused by a wide variety of sources. We describe the ambiguity problem, and identify those sources. We then define a set of visual states and transitions needed to resolve this ambiguity, of use to anyone designing touch applications or systems. We then present the Ripples implementation of visualizations for those states, and the results of a user study demonstrating user preference for the system, and demonstrating its utility in reducing errors.