The Impact of Interruptions and Multitasking On Knowledge Worker Efficiency and Effectiveness

So this is going to get worse as I get older?

Interruptions and multitasking are two afflictions that take a tremendous toll on our ability to focus, complete tasks, and be productive.  Our own research on interruptions shows that the recovery time, that is, the time it takes an individual to return to a task after being interrupted, can be as much as 10 to 20 times the length of the original interruption.  This means a 30 second interruption can result in an average of five minutes of recovery time, and that is optimistically assuming that one returns to the original task and does not abandon it.

It’s already been established that multitasking is not really possible for the human brain to engage in with any efficiency; instead, it is really just a series of interruptions, or task switches.  Multitasking results in lowered efficiency in all of the tasks being performed: there is no substitute for focused thinking on a single task.

New research from the University of California, San Francisco, that was published this week in the Proceedings of the National Academy of Sciences shows that the impact of multitasking and interruptions on older people is even more pronounced.  The study took 20 young adults with an average age of 25, and 20 older adults, with an average age of 69, and showed both groups a landscape picture.  They were told to keep the picture in their mind, and were then shown an image of a face and were asked several questions about it.  Then the subjects were shown another landscape picture, and asked to determine if it matched the first picture they were shown.

While the subjects were being shown the images, their brains were being scanned using an fMRI machine to show brain activity.  Both groups were able to switch from the landscape picture to the face image with the same proficiency, however, the brain scans showed that the elderly subjects took longer to switch from thinking about the image of the face back to the landscape portraits.  (The younger subjects were negatively impacted as well, but not as severely as the older subjects.)

Dubbed an “interruption recovery failure” by the researchers, the findings suggest that, as we age, our ability to recover from interruptions is reduced.  Another (albeit unlikely) interpretation of the findings is that there are also cultural factors at work, such as the younger test group’s relatively higher exposure to high amounts of distraction and interruptions as they grow up.

A critical outcome from the study was that the initial hypothesis, that older people experienced more detrimental effects from interruptions because they fixated on the new interruption more than younger people, was false.  In fact, the degree to which the subjects switched focus to the interruption was the same regardless of age; it is the “interruption recovery failure,” or what we call recovery time, that set the groups apart.

For the knowledge worker, young or old, the study demonstrates not only the existence of the recovery time phenomenon but also that it may increase in severity with age.  We don’t yet fully understand the impact that excessive multitasking and interruptions have on the brain as it develops and ages, but we do know now that there is a very real impact on brain activity, and we should redouble our efforts to reduce both the interruptions we are subjected to, as well as those we inflict on others.

Cody Burke is a senior analyst at Basex.

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