: We describe a study on the influence of instant messaging (IM) on ongoing computing tasks. The study both replicates and extends earlier work on the cost of sending notifications at different times and the sensitivity of different tasks to interruption. We investigate alternative hypotheses about the nature of disruption for a list evaluation task, an activity identified as being particularly costly to interrupt. Our findings once again show the generally disruptive effects of IM, especially during fast, stimulus-driven search tasks. In addition, we show that interruptions coming early during a search task are more likely to result in the user forgetting the primary task goal than interruptions that arrive later on. These findings have implications for the design of user interfaces and notification policies that minimize the disruptiveness of notifications. Keywords: Notifications, user study, interruptions, information overload, divided attention 1 Introduction With the adv...

When an automating application needs a user's input or has feedback or other information for that user, it typically engages the user immediately, interrupting the user's current task. To empirically validate why unnecessarily interrupting a user's task should be avoided, we designed an experiment measuring the effects of an interruption on a user's task performance, annoyance, and anxiety. Fifty subjects participated in the experiment. The results demonstrate that an interruption has a disruptive effect on both a user's task performance and emotional state, and that the degree of disruption depends on the user's mental load at the point of interruption. We discuss the implications of these results in terms of building a system to better coordinate interactions between the user and applications competing for that user's attention.

To contribute to systems that reason about human attention, our work empirically demonstrates how a user’s mental workload changes during task execution. We conducted a study where users performed interactive, hierarchical tasks while mental workload was measured through the use of pupil size. Results show that (i) different types of subtasks impose different mental workload, (ii) workload decreases at subtask boundaries, (iii) workload decreases more at boundaries higher in a task model and less at boundaries lower in the model, (iv) workload changes among subtask boundaries within the same level of a task model, and (v) effective understanding of why changes in workload occur requires that the measure be tightly coupled to a validated task model. From the results, we show how to map mental workload onto a computational Index of Opportunity that systems can use to better reason about human attention.

Interruptions can have lower cost if delivered at moments of lower mental workload during task execution, and cognitive theorists have speculated that these moments occur at subtask boundaries. In this article, we empirically test this speculation by examining how workload changes during task execution, focusing on subtask boundaries. In a carefully controlled experiment, users performed several interactive tasks while their pupil dilation, a reliable measure of workload, was continuously measured. The workload data was precisely aligned to the corresponding models of task execution and analyzed. Our principal results include (i) workload changes throughout the execution of a goal-directed task; (ii) workload exhibits momentary decreases at subtask boundaries compared to the preceding subtasks; (iii) the amount of decrease is larger at boundaries higher in the task model; and (iv) different types of subtasks induce different amounts of workload. We situate these findings within resource theories of attention and discuss important implications for interruption management systems.

We demonstrate a novel query interface that enables users to construct a rich search query without any prior knowledge of the underlying schema or data. The interface, which is in the form of a single text input box, interacts in real-time with the users as they type, guiding them through the query construction. We discuss the issues of schema and data complexity, result size estimation, and query validity; and provide novel approaches to solving these problems. We demonstrate our query interface on two popular applications; an enterprise-wide personnel search, and a biological information database.

In the recent development of a human-in-the-loop simulation test bed designed to examine human performance issues for supervisory control of the Navy’s new Tactical Tomahawk missile, measurements of operator situation awareness (SA) and workload through secondary tasking were taken through an embedded instant messaging program. Instant message interfaces (otherwise known as “chat”), already a means of communication between Navy ships, allow researchers to query users in real-time in a natural, ecologic setting, and thus provide more realistic and unobtrusive measurements. However, in the course of this testing, results revealed that some subjects fixated on the real-time instant messaging secondary task instead of the primary task of missile control, leading to the overall degradation of mission performance as well as a loss of SA. While this research effort was the first to quantify command and control performance degradation as a result of instant messaging, the military has recognized that in its network centric warfare quest, instant messaging is a critical informal communication tool, but has associated problems. Recently a military spokesman said that managing chat in current military operations was sometimes a “nightmare ” because military personnel have difficulty in handling large amounts of information through chat, and then synthesizing knowledge from this information. This research highlights the need for further investigation of the role of instant messaging interfaces both on task performance and situation awareness, and specifies how the associated problems could be ameliorated through adaptive display design.

With a focus on presenting information at the right time, the ubicomp community can benefit greatly from learning the most salient human measures of cognitive load. Cognitive load can be used as a metric to determine when or whether to interrupt a user. In this paper, we collected data from multiple sensors and compared their ability to assess cognitive load. Our focus is on visual perception and cognitive speed-focused tasks that leverage cognitive abilities common in ubicomp applications. We found that across all participants, the electrocardiogram median absolute deviation and median heat flux measurements were the most accurate at distinguishing between low and high levels of cognitive load, providing a classification accuracy of over 80 % when used together. Our contribution is a real-time, objective, and generalizable method for assessing cognitive load in cognitive tasks commonly found in ubicomp systems and situations of divided attention. Author Keywords Cognitive load, divided attention, interruption, psychophysiological

Interruptions are often seen as distracting or sometimes devastating elements that need to be minimized or eliminated. However, interruptions are also used to increase efficiency, productivity, prevent errors, and even influence behavior. Existing theories and taxonomies of interruptions fail to account for the helpful aspects of interruptions. Therefore we propose a theoretical framework to help explain the positive aspects of interruptions. Warnings & alerts, reminders, suggestions and notifications are examples of interruptions that have beneficial outcomes by changing and influencing behavior. We propose a cognitive theory of interruptions based on the properties of the users, their tasks, and best presentations depending on the desired effectiveness of the interruption. Norman’s 7-stage action model serves to explain how and why an interruption is accepted, and potential mismatches between the goal of the interruption and the user. Potential applications of this model include better understanding the effects of interruptions, and guidance to design effective and persuasive warnings and alerts, reminders, suggestions and notifications.

Cartographers ’ main objective in map design is to create in the mind of a map reader (i.e. user) an abstraction of the real world appropriate to the map’s purpose. The final result depends, not only on the cartographers’, but also users ’ skills and ways to perceive, as well as on the map usage situation. Interruptions during map reading process of mobile maps occur, when the conceptual models of the cartographer and the user do not match, e.g. if the user does not understand the symbols, or the overall layout of the mobile map. This can be frustrating from the users’ point of view. It is thought here, that by bringing context awareness into the maps on mobile devices, interruptions in map reading process could be decreased, by providing each user with symbols that are adapted to the usage situation and user preferences in real-time. In this paper some ideas, of how to implement context awareness into mobile maps by personalisation, are presented. Categories and Subject Descriptors Implications for adaptive behaviour, Leisure/entertainment use, Personalisation of services

In this paper, a novel means of status display in mobile phones is discussed: A permanent tactile heartbeat-like pulsation of the phone. In the study presented, this pulse was used to let the phone continuously communicate a calm state of ‘Everything is okay. ’ – then, this pulse was suddenly interrupted, as soon as the phone needed the user’s attention. We hypothesized that the users would instantly notice the missing pulse. The participants in our study wore the phone for one day and were interviewed afterwards. Also, a log file about the events and user responses was kept on the phone. The results suggest that the proposed system is not sufficient as a means of notification; only 55 % of the events were noticed within the first minute. While some users were simply annoyed by the pulse, others did like the reassurance that the phone was ‘present and calm’, but ‘easy to ignore’ at the same time. These results indicate that the system might be eligible as an ambient status display for mobile phones.