Indexical Representations for Context-aware Mobile Devices

Wireless mobile devices present a present a huge design and representational challenge for the discipline of humancomputer interaction. Past approaches have focused on user, task and artifact. This paper argues that in addition to these factors an understanding of context can assist with meeting design challenges for mobile applications. It proposes a matrix of eight dimensions of context drawn from existent taxonomies in ethnography, socio-linguistics and humancomputer interaction. The dimensions are described as time, absolute location, relative location, physical objects, activity, social setting, environment and culture. These are used to drive the design of interface representations for a route planning tool for use on the Melbourne public transport system. Central to the representations of information on the interfaces is the concept of index borrowed from semiotics and the idea of indexicality as an interface property. This paper illustrates how this concept can be used to develop interfaces for mobile devices and considers further applications and limitations of this approach.