Gestural Interfaces Must Be Part of a Multi-Modal Experience

In-the-air gestural interfaces, which are also called Spacial Interfaces, have some advantages and a lot of drawbacks. It's difficult for me see in-the-air gestures being used as the only mode of interaction. They will need to be augmented by other interfaces such as touch or speech in order to be effective.

Nicolas Nova posted an great pros & cons slide about gestural interfaces. While the pros are wonderful, the cons can be horrible. In particular fatigue and "immersion syndrome" seem to be really big problems.

I can't imagine using an interface that can only responded to in-the-air gestures. The potential for error seems enormous and I think users would find it frustrating. I can see, however, in-the-air gestures used in combination with a tangible like the Wii remote (that obviously works) or with voice commands to prompt interpretation of a gesture. I suspect that over time combining in-the-air gestures with tangibles (e.g. wands) and direct voice will become the most common multi-modal solution when using in-the-air gestures. You just can't make in-the-air gestural systems work without augmenting them with another mode of interaction.

Even Project Natal, which is probably one of the most advanced in-the-air gestural interfaces I've seen, uses multi-modal input. For example, Project Natal (or at least the demos they showed last year) used facial recognition and voice commands in its interfaces. While Project Natal is very exciting, I have some serious doubts about using in-the-air gesture interfaces as the primary mode of input to an interface.