Well, humans aren't designed, but we did evolve holding our arms in front of our faces making small motions.
http://en.wikipedia.org/wiki/List_of_gestures
I know it's hard to remember around here, but it's not just a UI buzzword.
(Which is why I see promise in this tech; using touchscreens is unnatural, but using gestures in front of your body to communicate with something a couple of feet away is quite human.)
Maybe that's the solution to gestural interfaces - quit with the in-front-of-my-face stuff, and go towards more sustainable movements, like we already have with keyboards and mice; everything at elbow height.
I'm not envisioning it as a primary input device, naturally (although the deaf seem to get by fine). But I don't think I've ever been in a situation where a heated conversation made my arms tired; as a replacement for a few basic mouse tasks, I bet it could even improve ergonomics.
Just try it: raising your arms as if gesturing conversationally is way, way less stressful than reaching out to touch your monitor.
Also, the gorilla arm would go away fairly quickly. This used to make me tired:
http://www.youtube.com/watch?v=mPKbCsWLe4k
Now it doesn't. I expect people would get used to minority report interfaces, particularly if they didn't immediately try to transition from 8 hours of keyboard to 8 hours of minority report.
My real question: is source code for this demo available?
I work in construction, I spend my days holding 5lb drills in front of me. Using the standard gesture position (forearm down) your arm won't get tired during a day. I basically live my day in the 'gesture position' often for well over 8 hours a day, always with weights in them.
When the upper arm is lifted is when your arms get not so much tired but literally drained, which is what I think the Kinect will likely have to adapt to.
I saw him at a small conference recently talking about the future of these types of interfaces and I think where he's going is trying to make much smaller movements meaningful. One example was having EPG on your TV that you could navigate by just flicking your hand. He's looking at ways that smaller, more natural movements can be used to for controlling a lot of the interfaces around you.
(behind pay wall unfortunately ) http://www.wired.co.uk/magazine/archive/2010/03/start/dale-h...
The side-effect that destroyed touch-screens as a mainstream input technology despite a promising start in the early 1980s. It seems the designers of all those spiffy touch-menu systems failed to notice that humans aren't designed to hold their arms in front of their faces making small motions. After more than a very few selections, the arm begins to feel sore, cramped, and oversized — the operator looks like a gorilla while using the touch screen and feels like one afterwards. This is now considered a classic cautionary tale to human-factors designers; “Remember the gorilla arm!” is shorthand for “How is this going to fly in real use?”.[1]
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[1]: http://ftp.sunet.se/jargon/html/G/gorilla-arm.html