Saturday, October 24, 2009

Limiting the multi-touch vocabulary

On the classic Nintendo Entertainment System, and many other game systems, there was an extremely limited controller vocabulary.
  • Four way direction-pad
  • A
  • B
  • Select
  • Start
The entire game library of NES, Gameboy, and several other game systems existed in a world with only these five controls. In fact, many games didn't even use all of them! I remember being surprised when a game uses the select button.

At first, it might seem that having so few controls would be a limitation and result in obscure and non-intuitive control schemes. On the contrary, game designers pay a huge amount of attention to usability and design their games so people can pick them up and use them without much thought. Otherwise, gamers would quickly lose patience and their games wouldn't sell.

With multi-touch systems, the possibilities of many touches and complicated gestures seems to blind designers and developers from the fact that you don't really need a rich vocabulary to navigate an application. There are already a few common gestures that are almost universally supported and used across all of the different multi-touch platforms:
  • Tap
  • Pan
  • Pinch in/out
  • Rotate
Using only these few gestures we could build hundreds of applications. In fact, most applications would only need Tap and Pan. (I'm assuming the keyboard would still be used, as necessary.)

Sure, in scenarios that need it, more complicated or custom gestures and manipulations could be used, just like how later game consoles added a few more buttons. But even the latest games use a few primary controls or buttons and the others are only used in special cases.

Before we get crazy, though, we should make an effort to really get the basic gestures right. Figure out what scenarios they should be used, and what metaphors work. Should Pinch In and Pinch Out be used for menu navigation? Does one or two finger rotation make more sense in which scenarios? The early game consoles had hardware and computational limitations that forced them to be creative and make intuitive interfaces. We shouldn't get caught up in all the possible gestures before getting the core set right.

The call to action here is when designing applications, think about the smallest set of multi-touch gestures that would accomplish the job. Can you design a more creative interface that only requires tap and pan? If so, then you might want to opt for that, since it requires the users to learn fewer gestures.

Hand Gesture diagrams adapted from Dan Saffer's graphics. Thanks for the contribution, Dan!

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