This transcript of an interview of Dan Saffer about his manifesto for gestural patterns for touch interaction is very pertinent. It's mostly about this wiki resource which aims at collecting and disseminating gestural interface information and patterns, such as found on such devices as the iPhone and Wii (following a discussion Adaptive Path's blog). Some excerpts of this interview:
"How do you document this gesture where I’m sweeping my hand across the screen?” (...) This is our generation’s drag and drop.” (...) I felt it was a really important thing for interaction designers to be doing because, otherwise, we’re going to start to end up with a thousand different ways of turning on my TV where it’s like, “Is this the Microsoft TV where I have to snap my fingers three times or is it the Apple one where I twirl around in a circle?” (...) one of the nice things about having it be in a completely digital medium is that one of the problems with gestures is certainly documenting them. How do you describe something that’s not very ambiguous? It’s awfully difficult with words to describe gestures or even in diagrams to describe gestures.So having the ability to eventually put up movie clips showing this as a pattern with people moving their forefinger and thumb apart, for instance, having that kind of rich experience would be really nice on the website."
(Picture taken from a wii game usability test I ran few months ago)
The examples he gives revolves around the Wii or the iPhone:
"The Wii certainly is very much about sort of movement in space. You’re not really touching anything except the controller. You’re kind of indirectly using a gesture. With the touch screen on the iPhone and other things, your fingertip is actually touching the device that you’re manipulating. So there is this gradation there."
Why do I blog this? this is indeed an interesting issue, how you describe these movements? can we have a grammar (i.e. a set of patterns). This has some tight connections with a project I am involved in that tries to map the wiimote and nunchuk movements of existing games in a database, this will then allow to analyze them and document their relative importance.