Mobile urban environments present a challenge for context-aware computers because they differ from fixed indoor contexts such as offices, meeting rooms, and lecture halls in many important ways. Internal factors such as tasks and goals are different---external factors such as social resources are dynamic and unpredictable. An empirical, user-centred approach is needed to understand mobile contexts. In this paper, we present insights from an ethnomethodologically inspired study of 25 adult urbanites in Helsinki. The results describe typical phenomena in mobility: how situational and planned acts intermesh in navigation, how people construct personal and group spaces, and how temporal tensions develop and dissolve. Furthermore, we provide examples of social solutions to navigation problems, examine mobile multitasking, and consider design implications for mobile and context-aware human-- computer interaction.

Mobile awareness systems provide user-controlled and automatic, sensor-derived cues of other users ’ situations and in that way attempt to facilitate group practices and provide opportunities for social interaction. We are interested in investigating how users interpret these cues as a situation, action, or intention of a remote person and then act on them in everyday social interactions. Three field trials utilizing A–B intervention research methodology were conducted with three types of teenager groups (N = 15, total days = 243). Each trial had a slightly different variation of ContextContacts—a smartphone-based multicue mobile awareness system. We report on several analyses on how the cues were accessed, viewed, monitored, inferred, and acted on. Antti Oulasvirta is a cognitive scientist with an interest in the psychology of mobile interaction; he is a researcher at the Helsinki Institute for Information Technology HIIT. Renaud Petit is a computer scientist with an interest in software for context-aware mobile services; he is a researcher in the From Data to Knowledge