Much of the previous research in context-aware computing has sought to ®nd a workable de®nition of context and to develop systems that could detect and interpret contextual characteristics of an user environment. However, less time has been spent studying the usability of these types of systems. This was the goal of our project. E-graf®ti is a context-aware application that detects the user's location on a college campus and displays text notes to the user based on their location. Additionally, it allows them to create notes that they can associate with a speci®c location. We released E-graf®ti to 57 students who were using laptops that could access the campus wireless network. Their use of E-graf®ti was logged in a remote database and they were also required to ®ll out a questionnaire towards the end of the semester.
The lessons learned from the evaluation of E-graf®ti point to themes other designers of ubiquitous and context-aware applications may need to address in designing their own systems. Some of the issues that emerged in the evaluation stage included dif®culties with a misleading conceptual model, lack of use due to the reliance on explicit user input, the need for a highly relevant contextual focus, and the potential bene®ts of rapid, ongoing prototype development in tandem with user evaluation.