# (user Number), Stp (successful Task Performance) Ert ( " Electronic Radio times " Based User's Model) 3.1 Methods for Eliciting Mental Models Figure 5: Create New Session Window 2.3 Communicating the Design Model

We report a case study in which conceptual design was applied to create a user interface of an innovative software tool. The Session Directory Tool (sdr) allows users to set up and participate in real-time interactive multimedia events on the Internet. To make this functionality available to users who are not familiar with the underlying network technology and videoconferencing, we identified a metaphor which could be extended into a design model (Electronic TV Listings Guide), and communicated this model through linguistic and structural features of the user interface. Evaluation results indicate that this effort was largely successful: new users handled sdr competently after a short training session and 5 days’ practise, and articulated their knowledge of the tool in terms related to the design model. The case study demonstrates the potential of conceptual design, integrated with tangible HCI design techniques, for developing user interfaces to innovative technology.