Do we need further “multi-touch” touch affordances?

People have developed sophisticated skills for sensing and manipulating their physical environments [1] with their fingers and hands. And more and more user interfaces taken advantage of that and allowing touch input to support these skills. Especially multi-touch interaction has received considerable attention in the last few years and the media interest in multi-touch interaction with large and small displays surfaces has seen a recent explosion. Multi-touch surfaces can be realized by using different technologies, ranging from capacitive sensing to video analysis of infrared or full colour video images [2–5]. In this paper we try to summarize some key values of multi-touch interaction. We think that is a first important step when thinking of methods to communicate touch-based interaction in an intuitive, implicit way or to evaluate the impact of a touch-related interface on user experience of success system. Because we think, it is important what values touch affordances afford. Do we need further multi-touch touch affordances? In 2005 Han [3] presented his low cost camera-based multi-touch sensing technique. His YouTube demonstration captured the imagination of researchers and users alike. Technologies that allow the low-cost implementation of robust multitouch interaction, such as Frustrated Total Internal Reflection (FTIR) and Diffused Illumination (DI), have allowed for the low cost development of such surfaces, have led to a number of technological and application innovations. Hans rediscovery and dissemination of the FTIR principle [3] has greatly accelerated the development of new multi-touch applications and attention in the news media. In particular, his demonstration of a range of creatively applied multi-touch interaction techniques. With today’s technology it is now possible to apply the basic advantages of bi-manual interaction [6–11] to any suitable domain. Bill Buxton gives a comprehensive overview of the history of development of multi-touch surface1. While the technology allows to use a rich set of gestures to explore complex data (e.g. geodata, any sort of media or medical data) often these gestures are hard to learn for users and often users are not sure what gestures will lead to which action. To understand how people interaction with such new multi-touch systems we installed a geoapplication on a large-scale multi-touch screen during a technology exhibit called “Germany ‘Land of ideas’ ” in a pedestrian underway in the city of Münster for one week. The focus of our study lies on the observation of spontaneous and group interaction patterns. The video2 presents the short impression 1 http://www.billbuxton.com/multitouchOverview.html 2 Hightech-Underground on youtube: http://www.youtube.com/watch?v=