Designing Gestural Interfaces

DETERMINING THE APPROPRIATE GESTURE

Once you've decided that a gestural interface is appropriate for your users and your environment, you need to pair the appropriate gestures to the tasks and goals the users need to accomplish. This requires a combination of three things: the available sensors and related input devices, the steps in the task, and the physiology of the human body. Sensors determine what the system can detect and how. The steps in the task show what actions have to be performed and what decisions have to be made. The human body provides physical constraints for the gestures that can be done (see Chapter 2).

For most touchscreens, this can be a very straightforward equation. There is one sensor/input device (the touchscreen); the tasks (check in, buy an item, find a location, get information) are usually simple. The touchscreen needs to be accessible and used by a wide variety of people of all ages. Thus, simple gestures such as pushing buttons are appropriate.

Note

The complexity of the gesture should match the complexity of the task at hand.

This is to say that simple, basic tasks should have equally simple, basic gestures to trigger or complete them, for instance, taps, swipes, and waves. More complicated tasks may have more complicated gestures.

Take, for example, turning on a light. If you just want to turn on a light in a room, a wave or swipe on a wall should be sufficient for this simple behavior. Dimming the light (a slightly more complex action), however, may ...