Interruption studies typically focus on external interruptions, even though self-interruptions occur at least as often in real work environments. In this article, we therefore contrast external interruptions with self-interruptions. Three multitasking experiments were conducted, in which we examined changes in pupil size when participants switched from a primary to a secondary task. Results showed an increase in pupil dilation several seconds before a self-interruption, which we could attribute to the decision to switch. This indicates that the decision takes a relatively large amount of time. This was supported by the fact that in Experiment 2, participants were significantly slower on the self-interruption blocks than on the external interruption blocks. These findings suggest that the decision to switch is costly, but may also be open for modification through appropriate training. In addition, we propose that if one must switch tasks, it can be more efficient to implement a forced switch after the completion of a subtask instead of leaving the decision to the user.

No abstract

No abstract

Interruptions are prevalent in everyday life and can be very disruptive. An important factor that affects the level of disruptiveness is the timing of the interruption: Interruptions at low-workload moments are known to be less disruptive than interruptions at high-workload moments. In this study, we developed a task-independent interruption management system (IMS) that interrupts users at low-workload moments in order to minimize the disruptiveness of interruptions. The IMS identifies low-workload moments in real time by measuring users' pupil dilation, which is a well-known indicator of workload. Using an experimental setup we showed that the IMS succeeded in finding the optimal moments for interruptions and marginally improved performance. Because our IMS is task-independent-it does not require a task analysis-it can be broadly applied.

Potential applications of this research include the minimization of delays in task design and the inability or discouragement of switching in high-workload moments.