User-interruption in human-computer interaction (HCI) is an increasingly important problem. Many of the useful advances in intelligent and multitasking computer systems have the significant side effect of greatly increasing user-interruption. This previously innocuous HCI problem has become critical to the successful function of many kinds of modern computer systems. Unfortunately, no HCI design guidelines exist for solving this problem. In fact, theoretical tools do not yet exist for investigating the HCI problem of user-interruption in a comprehensive and generalizable way. This report asserts that a single unifying definition of user-interruption and the accompanying practical taxonomy would be useful theoretical tools for driving effective investigation of this crucial HCI problem. These theoretical tools are constructed here. A comprehensive analysis is conducted through the existing literature. Theoretical constructs from several relevant but diverse fields are identified and discussed. A unifying definition of user-interruption is synthesized. This new definition is supported with an array of postulates, assertions, and a taxonomy of human interruption to facilitate its practical application.

Video games are of increasing importance, both as a cultural phenomenon and as an application of collaborative technology. In particular, many recent online games feature persistent collaborative virtual environments (CVEs), with complex social organisation and strong social bonds between players. This paper presents a study of `There', one such game, focusing on how There has been appropriated by its players. In particular we describe how its flexibility has allowed players t o develop their own forms of play within the game. Three aspects of There are discussed: first, how the environment supports a range of social activities around objects. Second, how the chat environment is used to produce overlapping chat and how the game itself provides topics for conversation. Lastly, how the `place' of There is a fluid interaction space that supports safe interactions between strangers. The paper concludes by drawing design lessons concerning the importance of supporting shared online activity, interaction between strangers, and the difficulties of designing for play.

Acontextuality of the mobile phone often leads to a caller's uncertainty over a callee's current state, which in turn often hampers mobile collaboration. We are interested in re-designing a Smartphone's contact book to provide cues of the current situations of others. ContextContacts presents several meaningful, automatically communicated situation cues of trusted others. Its interaction design follows social psychological findings on how people make social attributions based on impoverished cues, on how self-disclosure of cues is progressively and interactionally managed, and on how mobility affects interaction through cues. We argue how our design choices support mobile communication decisions and group coordinations by promoting awareness. As a result, the design is very minimal and integrated, in an "unremarkable" manner, to previously learned usage patterns with the phone. First laboratory and field evaluations indicate important boundary conditions for and promising avenues toward more useful and enjoyable mobile awareness applications.

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This paper reports on the development of a multi-agent simulation of small group discussion that focusses on the interaction and the coordination of turn-taking. We describe the addition of nonverbal behaviours, such as gaze, gestures, posture shifts and head and facial expression, to the model; how the agents in the simulation take these behaviours into account in their decisions to speak, to stop, or to give feedback. The simulation is to be evaluated comparing its statistical profile against the statistics generated by a simpler, base model, one without the nonverbal behaviours, to show that it better approximates the statistics of a real group discussion. The properties to be assessed include mean transition intervals, turn lengths, relation of gaze to speaking order, frequency of simultaneous starts, and of feedback. 1

Abstract. Computer-mediated communication (CMC) is a keystone of computer-supported collaborative work. Current CMC theory utilizes an information channel metaphor in which media vary according to how well they afford the transfer of messages in the channel, i.e., bandwidth. This paper draws attention to a different aspect of communication argued to be equally important: a relation between people that defines a state of communicative readiness in which fruitful communication is likely. Drawing on research on instant messaging (Nardi et al., 2000) and face to face communication (Nardi et al., 2002; Nardi and Whittaker, 2003), as well as related literature, three dimensions of connection that activate readiness are proposed: affinity, commitment, and attention. These dimensions comprise a field of connection between dyads. A field of connection is conceptualized as a labile, multidimensional space in which the values of the dimensions vary according to the history of communicative activity. Affinity, commitment, and attention are constantly monitored, negotiated, and managed through social bonding, expression of commitment, and capture of attention. The management of fields of connection requires significant interactional work to sustain communication over time. Key words: affinity, attention, commitment, computer-mediated communication, interpersonal communication, social connection

Social context is an important yet an underresearched area in context-sensitive computing. This paper adopts a framework from social sciences that views social context as a sequence of turns taken between participants. The approach is illustrated and evaluated through three empirical cases. The results show that social context is not a static and passive surrounding of a device, but dynamic and constructed by people. Challenges and restrictions for modeling social context through turntaking are identified.

The argument for the involvement of social scientists in dependable socio-technical systems design reasons is that, to be dependable, systems need to be appropriate both for the application domain and potential users.

Context-awareness of social interaction is difficult for computers that are denied the social learning process of humans. Consequently, there has been scepticism about the enterprise. Basing on a turntaking analysis of group invitations, a complex social phenomenon, this pessimistic view is refuted. Turntaking provides an operationalizable account of social interaction and adds to the context debate by highlighting the dynamic and constructive aspects of context. Turns (actions) are recognizable by present-day technologies, but their sequential structures must be "hard-wired" by social scientists, as must be the meanings of static factors (e.g., location). Six challenges for attempts to implement turntaking as a model of social awareness are discussed.

This paper presents an algorithm for identifying noun-phrase antecedents of pronouns and adjectival anaphors in Spanish dialogues. We believe that anaphora resolution requires numerous sources of information in order to find the correct antecedent of the anaphor. These sources can be of different kinds, e.g., linguistic information, discourse/dialogue structure information, or topic information. For this reason, our algorithm uses various different kinds of information (hybrid information). The algorithm is based on linguistic constraints and preferences and uses an anaphoric accessibility space within which the algorithm finds the noun phrase. We present some experiments related to this algorithm and this space using a corpus of 204 dialogues. The algorithm is implemented in Prolog. According to this study, 95.9% of antecedents were located in the proposed space, a precision of 81.3% was obtained for pronominal anaphora resolution, and 81.5% for adjectival anaphora. 1.