Great at Work: The Hidden Habits of Top Performers

by Morten T. Hansen

Coordinating between priorities requires mental exertion. Many regard multitasking as efficient, but research shows that rapidly toggling between two items—reading emails and listening to a colleague’s presentation, for example—renders you less effective at both. Each time you switch, your brain must abandon one task and acclimate itself to the other. A study of 58,280 court cases before Italian judges in Milan found that the judges who handled many cases simultaneously (multitasking) took longer to complete them than those who performed them in sequence. The differences were striking: the slowest judge spent on average 398 days to close the cases, while the fastest took “only” 178 days, or less than half the time. (They all had the same workload and cases were assigned randomly, so their cases were comparable.) The researchers estimated that a 50 percent increase in multitasking led to a nearly 20 percent increase in the number of days to finish cases. Toggling cases slowed them down.17 Other studies have shown that switching between tasks can decrease your productivity by as much as 40 percent.18