Tangible user interfaces (TUI) have become an increasingly common way of building interactivity into digital experiences. TUIs on touch tables provide a physical interface for screen- based two-dimensional experiences. Digital objects allow multiple users to interact simultaneously and can be used in creating touch table applications that are omni-directional. But digital objects have another important impact: they invite people to treat the experience interactively, rather than as a simple information delivery system, and thus to explore content more deeply and connect the digital experience to their own lives. And, of course, tangible physical objects used in TUI-based exhibits are objects in the real world. They are persistent, and if presented correctly, create no ambiguity in terms of their use and function.
