The objective was to establish the nature of choice in cognitive multitasking.

Laboratory studies of multitasking suggest people are rational in their switch choices regarding multitasking, whereas observational studies suggest they are not. Threaded cognition theory predicts that switching is opportunistic and depends on availability of cognitive resources.

A total of 21 participants answered e-mails by looking up information (similar to customer service employees) while being interrupted by chat messages. They were free to choose when to switch to the chat message. We analyzed the switching behavior and the time they needed to complete the primary mail task.

When participants are faced with a delay in the e-mail task, they switch more often to the chat task at high-workload points. Choosing to switch to the secondary task instead of waiting makes them slower. It also makes them forget the information in the e-mail task half of the time, which slows them down even more.

When many cognitive resources are available, the probability of switching from one task to another is high. This does not necessarily lead to optimal switching behavior.

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