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.

Interruptions can cause people to make mistakes or errors during human--computer interaction (HCI). Interruptions occur as an unavoidable side-effect of some important kinds of human computer-based activities, for example, (a) constantly monitor for unscheduled changes in information environments, (b) supervise background autonomous services, and (c) intermittently collaborate and communicate with other people. Fortunately, people have powerful innate cognitive abilities that they can potentially leverage to manage multiple concurrent activities if they have specific kinds of control and interaction support. There is great opportunity, therefore, for user-interface design to increase people's ability to successfully handle interruptions, and prevent expensive errors. The literature contains very little concrete design wisdom about how to solve the interruption problems in user interfaces (UIs). Coordination support, however, is identified as a most important design topic. This article presents the results of an empirical investigation to compare basic design solutions for coordinating human interruption in computer -based multitasks. A theory-based taxonomy of human interruption is used

Peripheral information is information that is not central to a person's current task, but provides the person the opportunity to learn more, to do a better job, or to keep track of less important tasks. Though peripheral information displays are ubiquitous, they have been rarely studied. For computer users, a common peripheral display is a scrolling text display that provides announcements, sports scores, stock prices, or other news. In this paper, we investigate how to design peripheral displays so that they provide the most information while having the least impact on the user's performance on the main task. We report a series of experiments on scrolling displays aimed at examining tradeoffs between distraction of scrolling motion and memorability of information displayed. Overall, we found that continuously scrolling displays are more distracting than displays that start and stop, but information in both is remembered equally well. These results are summarized in a set of design recommendations.

This paper reports on TaskTracer — a software system being designed to help highly multitasking knowledge workers rapidly locate, discover, and reuse past processes they used to successfully complete tasks. The system monitors users ’ interaction with a computer, collects detailed records of users ’ activities and resources accessed, associates (automatically or with users ’ assistance) each interaction event with a particular task, enables users to access records of past activities and quickly restore task contexts. We present a novel Publisher-Subscriber architecture for collecting and processing users ’ activity data, describe several different user interfaces tried with TaskTracer, and discuss the possibility of applying machine learning techniques to recognize/predict users ’ tasks.

At first glance it seems absurd that busy people doing important jobs should want their computers to interrupt them. Interruptions are disruptive and people need to concentrate to make good decisions. However, successful job performance also frequently depends on people's abilities to (a) constantly monitor their dynamically changing information environments, (b) collaborate and communicate with other people in the system, and (c) supervise background autonomous services. These critical abilities can require people to simultaneously query a large set of information sources, continuously monitor for important events, and respond to and communicate with other human operators. Automated monitoring

This paper examines the theoretical and practical problems that arise from attempts to develop formal characterisations and explanations of many work activities; in particular, collaborative activities. We argue that even seemingly discrete individual activities occur in, and frequently draw upon a complex network of factors: individual, social and organisational. Similarly, organisational and social constraints and practices impact upon individual, cognitive processes and the realisation of these in specific tasks. Any adequate characterisation of work activities therefore requires the analysis and synthesis of information from these, traditionally separate sources. We argue that existing frameworks, emanating separately from the respective disciplines (cognitive, social and organisational) do not present an adequate means of studying the dynamics of collaborative activity in situ. An alternative framework, advocated in this paper, is distributed cognition. Its theoretical basis is outlined together with examples of applied studies of computer-mediated work activities in different organisational settings. 1.

A prerequisite to the effective design of user interfaces is an understanding of the tasks for which that interface will actually be used. Surprisingly little task analysis has appeared for one of the most discussed and fastest-growing computer applications, browsing the World-Wide Web (WWW). Based on naturally-collected verbal protocol data, we present a taxonomy of tasks undertaken on the WWW. The data reveal that several previous claims about browsing behavior are questionable, and suggests that that widgetcentered approaches to interface design and evaluation may be incomplete with respect to good user interfaces for the Web.

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The number of computing devices that people use is growing. To gain a better understanding of why and how people use multiple devices, we interviewed 27 people from academia and industry. From these interviews we distill four primary findings. First, associating a user’s activities with a particular device is problematic for multiple device users because many activities span multiple devices. Second, device use varies by user and circumstance; users assign different roles to devices both by choice and by constraint. Third, users in industry want to separate work and personal activities across work and personal devices, but they have difficulty doing so in practice Finally, users employ a variety of techniques for accessing information across devices, but there is room for improvement: participants reported managing information across their devices as the most challenging aspect of using multiple devices. We suggest opportunities to improve the user experience by focusing on the user rather than the applications and devices; making devices aware of their roles; and providing lighter-weight methods for transferring information, including synchronization services that engender more trust from users. Author Keywords User study, multiple devices, personal computing, personal information management, cross device interaction ACM Classification Keywords H5.m. Information interfaces and presentation (e.g., HCI):

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