Bits are Cheap, Atoms are Expensive: Critiquing the Turn Towards Tangibility in HCI

Ever since the introduction of the desktop interface, HCI has strived to develop alternatives that make interacting with computers more physical, embodied and ubiquitous. In particular, the vision of tangible user interfaces (TUI) has had a large impact and inspired an extensive body of research over the last 25 years. However, despite strong interest from the research community, commercial success has been limited. We argue that the reason is that whereas graphical user interfaces are inherently cheap, physical interfaces are expensive: to create; to control; to modify; to maintain; and to mass-produce and distribute. This also leads to TUIs being highly problematic from a sustainability viewpoint. Finally, as a way to combine the best of both worlds, we introduce a vision of liberated pixels, which are visual output elements that are perceivable, addressable, and persistent in the physical world.