Designing Gestural Interfaces

METHODS OF COMMUNICATING INTERACTIVE GESTURES

You can communicate both the key presence and the instruction in several ways. As with most design decisions, the method of communication depends heavily on how it will be used and by whom. Detailed written instructions, for instance, will be useless for situations in which the users are illiterate or in locations such as a busy city street. Illustrations need to be of a certain size to be understood. Demonstrations need a means with which to view them.

Further complicating the methods of communication is the difficulty in communicating multiple gestures at once. You should avoid this if possible, but sometimes, as with trackpads and wall displays, you can't. With multiple gestures in a single space, the following methods may have to be layered on (as stickers or perhaps as a help mode that can be turned on).

WRITTEN INSTRUCTIONS

Written instructions are a basic choice and make sense for simple actions—touch here to begin, slide to unlock, clap hands to turn on lights—that is, actions that are in common use and/or are unambiguous enough to be explained in text.

Note

Use written instructions for simple, unambiguous gestures.

Written instructions, because of their possible small size, can easily fit in places that other communication methods cannot, such as on small devices, and into different environments.

Figure 7-7. Politeness in the messaging, ...