"Multi-touch systems that I have known and loved" 29 Aug 2007

The success of the all-conquering iPhone means that more and more interaction designers are becoming interested in working with multi-touch user interfaces. However, as a quick web search will confirm, there isn't a great deal of information available on designing for these types of system. We were therefore excited to stumble across Bill Buxton's essay on "Multi-touch systems that I have known and loved". Bill has been working with multi-touch interfaces since 1984, so if anyone knows about this technology, it's him. Here are some of his key insights...

"If you are blind you are simply out of luck. (P.S. we are all blind at times - such as when lights are out, or our eyes are occupied elsewhere - such as on the road). On their own, soft touch screen interfaces are nearly all 'eyes on'. You cannot 'touch type', so to speak, while your eyes are occupied elsewhere...With an all touch-screen interface you generally cannot start, stop, or pause your MP3 player, for example, by reaching into your pocket / purse / briefcase. Likewise, unless you augment the touch screen with speech recognition for all functions, you risk a serious accident trying to operate it while driving. On the other hand, MP3 players and mobile phones mechanical keys can to a certain degree be operated eyes free - the extreme case being some 12-17 year old kids who can text without looking!"

"Your finger is not transparent: The smaller the touch screen the more the finger(s) obscure what is being pointed at. Fingers do not shrink in the same way that chips and displays do. That is one reason a stylus is sometimes of value: it is a proxy for the finger that is very skinny, and therefore does not obscure the screen."

"Sunshine: We have all suffered trying to read the colour LCD display on our MP3 player, mobile phone and digital camera when we are outside in the sun. At least with these devices, there are mechanical controls for some functions. For example, even if you can't see what is on the screen, you can still point the camera in the appropriate direction and push the shutter button. With interfaces that rely exclusively on touch screens, this is not the case. Unless the device has an outstanding reflective display, the device risks being unusable in bright sunlight."