Computer-based work often involves looking up information from different sources. Though these interruptions are required to progress with work, switching away from a task can be disruptive: it slows people down, increases errors and it is challenging to remain focused on work. This thesis investigates how interruption management tools can better support people in managing these types of work-required interruptions in the context of data entry work. The first part of the thesis reports two qualitative studies looking at understanding data entry in an office setting. They demonstrate that physical interruptions are postponed until a convenient moment in the task if they are expected to take time, but digital interruptions are addressed immediately as these are presumed to be quick to deal with. The second part of the thesis reports three controlled experiments to test the hypothesis that people manage interruptions by avoiding time costs. Results show that if people are able to learn the expected time costs of digital interruptions, they avoid interruptions with a high time cost. They reduce the number of these interruptions and postpone them until later in the task, and address interruptions with low time costs first. The third part of the thesis reports an online experiment and a field study that evaluate a design intervention showing people the duration of their interruptions. These studies demonstrate that making people aware of the time costs of digital interruptions makes people reflect on what they were doing during an interruption, reduces the duration of interruptions, and makes people faster and more accurate in completing data entry tasks. Taken together, this thesis demonstrates that people manage interruptions based on expected time costs, and that giving people feedback on the time they spend on interruptions can help them manage their interruptions better. It makes a theoretical contribution by showing how people adapt to small changes in time costs by reducing the number and duration of interruptions, and postponing them until later in a task. It makes a practical contribution by showing that giving people feedback on time costs can help them to reduce the duration of interruptions, and improve their focus on the task at hand
