Designing Gestural Interfaces

DIRECT VERSUS INDIRECT MANIPULATION

The ease of use one experiences with a well-designed touchscreen comes from what University of Maryland professor Ben Shneiderman coined as direct manipulation in a seminal 1983 paper.^[2] Direct manipulation is the ability to manipulate digital objects on a screen without the use of command-line commands—for example, dragging a file to a trash can on your desktop instead of typing del into a command line. As it was 1983, Shneiderman was mostly talking about mice, joysticks, and other input devices, as well as then-new innovations such as the desktop metaphor.

Touchscreens and gestural interfaces take direct manipulation to another level. Now, users can simply touch the item they want to manipulate right on the screen itself, moving it, making it bigger, scrolling it, and so on. This is the ultimate in direct manipulation: using the body to control the digital (and sometimes even the physical) space around us. Of course, as we'll discuss in Chapter 4, there are indirect manipulations with gestural interfaces as well. One simple example is The Clapper.

Figure 1-3. The Clapper turns ordinary rooms into interactive environments. Occupants use indirect manipulation in the form of a clap to control analog objects in the room. Courtesy Joseph Enterprises.

The Clapper was one of the first consumer devices sold with an auditory sensor.^[3] It plugs into an electrical ...