Resistance to the impact of interruptions during multitasking by healthy adults and dysexecutive patients.

Two experiments (one with healthy adult volunteers and the other with controls and dysexecutive patients) assessed the impact of interruptions on a novel test of multitasking. The test involved switching repeatedly between four tasks (block construction, bead threading, paper folding, alphabetical searching) over a 10 min period. In Experiment 1, there were four groups of 20 healthy participants. One group attempted multitasking with no interruption, a second group was interrupted early in the test, a third group late in the test and a fourth group was interrupted both early and late. Interruption involved carrying out a fifth, unexpected task for a period of 1 min before returning to the four main tasks. There was no difference in multitasking performance between the groups. In Experiment 2 the participants were seven dysexecutive patients and 14 age-matched controls. A repeated measures approach was employed to assess the impact of two interruptions (early and late) for both groups. Contrary to predictions, the patients as well as controls were resistant to the effects of interruptions, despite their clearly impaired multitasking performance. These results suggest that the ability to deal with interruptions may be separable from the ability to organise and execute multiple tasks within a limited time frame.