Communications - June 2008

display. What kind of new interfaces would be possible with such a hypothetical device?

The resulting interface concept and prototype allows users to browse digital media by a combination of physical deformation and 2D position control. Held in both hands, the device can be bent along one axis while a touchpad mounted on the back of the device is used to control 2D position. With a simple, consistent vocabulary of physical interactions, it is possible to navigate file structures, maps, hyperlinks, photo albums, and movies. We also implemented a street map that can be scrolled

Figure 2. Gummi device and interaction.

with the touchpad and zoomed by bending the device (see Figure 1). The flat prototype can be bent either away from or toward the user to control zoom direction (see Figure 2). The amount of bending is mapped to zoom speed: slight deformation results in a slow, continuous zoom; stronger bending increases the zoom speed. This kind of analog interaction has two benefits. It gives the user finer control over the feature in question and it feels organic because it is as sensitive to the nuances and transitions of physical interaction as a real-world object.

Although Gummi was inspired by new hardware technology, the use of analog sensors in the resulting prototype became a focus for the project. We realized that capturing analog, continuous physical interaction led to an interface that offered interest-

ing new functional possibilities, while at the same time feeling very organic.

Two recently released products feature analog interaction techniques. The Nintendo Wii gaming platform includes an input device that adds hand and arm gestures to the interaction vocabulary of game interfaces. Apple’s iPhone represents the first mass-marketed product that uses multi-touch interaction. Its responsive graphical user interface incorporates subtle, animated visual behaviors that add up to create a very tactile, organic user experience.

Analog interaction techniques arguably played an important role in the success of both the Wii and the iPhone and recent technological developments suggest there is a lot of room for exploration in this area: small, inexpensive sensors can capture a wide range of analog physical inputs such as gestures, pressure, deformation, multi-point touch, orientation, and location. New materials, such as organic LED displays, point toward flexible computers that can sense their own shape. Mobile devices with fast processors and high-resolution displays support graphical user interfaces that can match the subtle, analog nature of physical interaction.

The examples mentioned here share a number of characteristics that contribute to the organic feel of these interfaces: by using analog sensors in input devices, continuous and subtle changes in physical interaction can be measured. The analog complexity of input is reflected in a highly responsive graphical user interface, featuring smooth animation and consistent visual behavior. As a result, the input device and graphical user interface are experienced as a whole, not as independent elements of the interface. The cumulative effect of these characteristics is a user interface that inspires a suspension of disbelief: intangible information feels as though it is part of our tangible physical environment. ^c

REFERENCE

1. Schwesig, C., Poupyrev, I., and Mori, E. Gummi: A bendable computer. E. Dykstra-Erickson and M. Tscheligi, Eds. In Proceedings of ACM CHI 2004 Conference on Human Factors in Computing Systems (Vienna, Austria, 2004), 263–270.