Tangible User Interface
(previously known as Graspable User Interface)
The term Tangible User Interface (TUI) was first introduced by MIT’s Tangible Media Group (led by Hiroshii Ishii) who are also well-known for their visions of Tangible Bits and Radical Atoms. It describes an interactive user interface based on physical embodiment of digital information as tangible objects. These so-called tangibles are used as well as controls (input) and representations (output), making data and the impact of interaction on data literally graspable. Users are provided with parallel feedback loops: physical, passive haptic feedback informs users that a certain physical manipulation is complete; and digital, visual or auditory feedback informs users of the computational interpretation of their action. Interactions and object manipulations are tracked by cameras placed behind the surface or using touch screens with electrically conductive materials.
Application areas for TUIs are collaboration, social communication, learning, support of planning and problem solving, programming and simulation tools, information visualization and exploration, entertainment, performance and music. The design space of TUIs includes 2D / 3D space and virtual, augmented or mixed reality applications.
According to Ullmer at al. in Token+constraint systems for tangible interaction with digital information the 3 main approaches of TUIs are
- tangible objects with interactive (tabletop) surfaces,
- constructive assemblies of modular connecting blocks (similar to the model of physical construction kits) and
- token–constraint systems with physical “complementarities” such as plug and socket (tokens represent digital information or interactions of an application and constraints limit the interaction space)
Examples
One early example is Durrell Bishop’s Marble Answering Machine, which physicalizes incoming voice messages as marbles. With each new voice message marbles fall automatically in a container. Users can move marbles to different containers to perform actions, such as listening to a message or call back. The Marble Answering Machine is considered to be an token-constraint TUI.
Reactable is a commercial modular synthesizer with a translucent tabletop TUI designed for hotels, museums or music live performances. Sound effects are controlled by placing or rotating tangibles with painted symbols on the display, each of them representing a different synth module. The table displays graphics such as waveforms or circles as the tangibles placed. Reactable has an app successor called Rotor that combines standard multi-touch capabilities with tangible input.