As economics students know, switching involves costs. But how much? When a consumer switches banks, or a company switches suppliers, it’s relatively easy to count the added expense of the hassle of change. When your brain is switching tasks, the cost is harder to quantify.
There have been a few efforts to do so: Gloria Mark of the University of California, Irvine, found that a typical office worker gets only 11 minutes between each interruption, while it takes an average of 25 minutes to return to the original task after an interruption. But there has been scant research on the quality of work done during these periods of rapid toggling.
We decided to investigate further, and asked Alessandro Acquisti, a professor of information technology, and the psychologist Eyal Peer at Carnegie Mellon to design an experiment to measure the brain power lost when someone is interrupted.
To simulate the pull of an expected cellphone call or e-mail, we had subjects sit in a lab and perform a standard cognitive skill test. In the experiment, 136 subjects were asked to read a short passage and answer questions about it. There were three groups of subjects; one merely completed the test. The other two were told they “might be contacted for further instructions” at any moment via instant message.
During an initial test, the second and third groups were interrupted twice. Then a second test was administered, but this time, only the second group was interrupted. The third group awaited an interruption that never came. Let’s call the three groups Control, Interrupted and On High Alert.
We expected the Interrupted group to make some mistakes, but the results were truly dismal, especially for those who think of themselves as multitaskers: during this first test, both interrupted groups answered correctly 20 percent less often than members of the control group.
Based on this information, is there really an advantage to having two monitors? I think not…