The fundamental nature of grocery shopping makes it an interesting domain for intelligent mobile assistants. Even though the central role of shopping lists is widely recognized, relatively little attention has been paid to facilitating shopping list creation and management. In this paper we introduce a predictive text input technique that is based on association rules and item frequencies. We also describe an interface design for integrating the predictive text input with a web-based mobile shopping assistant. In a user study we compared two interfaces, one with text input support and one without. Our results indicate that, even though shopping list entries are typically short, our technique makes text input significantly faster, decreases typing error rates and increases overall user satisfaction.

We present data from detailed observations of CityWall, a large multi-touch display installed in a central location in Helsinki, Finland. During eight days of installation, 1199 persons interacted with the system in various social configurations. Videos of these encounters were examined qualitatively as well as quantitatively based on human coding of events. The data convey phenomena that arise uniquely in public use: crowding, massively parallel interaction, teamwork, games, negotiations of transitions and handovers, conflict management, gestures and overt remarks to co-present people, and "marking" the display for others. We analyze how public availability is achieved through social learning and negotiation, why interaction becomes performative and, finally, how the display restructures the public space. The multi-touch feature, gesture-based interaction, and the physical display size contributed differentially to these uses. Our findings on the social organization of the use of public displays can be useful for designing such systems for urban environments.

Most large public displays have been used for providing information to passers-by with the primary purpose of acting as one-way information channels to individual users. We have developed a large public display to which users can send their own media content using mobile devices. The display supports multi-touch interaction, thus enabling collaborative use of the display. This display called CityWall was set up in a city center with the goal of showing information of events happening in the city. We observed two user groups who used mobile phones with upload capability during two large-scale events happening in the city. Our findings are that this kind of combined use of personal mobile devices and a large public display as a publishing forum, used collaboratively with other users, creates a unique setting that extends the group's feeling of participation in the events. We substantiate this claim with examples from user data.