Designed for Use, 2nd Edition

Avoid Gesture Magic

If you choose gestures, make sure they directly and immediately affect things on the screen in a familiar way that users understand from the real world. Gestures work best when the system gives constant feedback while the user is interacting with it. In Designing Gestural Interfaces [Saf08], Dan Saffer points out:

We’re used to instant reaction to physical manipulation of objects. (...) When engaged with a gestural interface, users want to know that the system has heard and understood any commands given to it. This is where feedback comes in. Every action by a human directed toward a gestural interface, no matter how slight, should be accompanied by some acknowledgment of the action—whenever possible and as rapidly as possible. ...