Why doesn't multitasking work?

Multitasking doesn’t work because, for anything demanding, the brain does not run two tasks in parallel. It switches between them, and every switch costs time. If you pride yourself on multitasking, that is an uncomfortable, well-evidenced fact: the thing you are actually doing is making you slower. The brain is a serial processor that switches fast, and switching is not free.

Is multitasking actually possible?

No, not for attention-demanding tasks. The clearest evidence comes from the study of task switching. In a set of experiments published in 2001, the psychologists Joshua Rubinstein, David Meyer and Jeffrey Evans had people alternate between tasks and measured what it cost.^[1] Every time participants switched, they lost time, and the loss grew with how complex and unfamiliar the tasks were. The reason is that switching involves hidden mental steps: disengaging from the rules of one task and loading the rules of the next. You do not notice these steps, but they add up. Doing two things by alternating is reliably slower and more error-prone than doing each in turn.

So when you answer a message mid-task, you do not pay only the seconds of reading it. You pay the cost of leaving your task and the cost of finding your way back into it.

How long does it take to refocus after an interruption?

23 minutes, on average, and that return cost is larger than almost anyone guesses. The attention researcher Gloria Mark, who has tracked people’s focus at work for two decades, found that after an interruption it took on average more than 23 minutes to get back to the original task.^[3] A day sprinkled with “quick” checks is therefore a day in which deep attention barely gets a chance to form before it is broken again.

Does multitasking change your brain?

Yes, possibly, though this is still debated. In a 2009 study, Eyal Ophir, Clifford Nass and Anthony Wagner compared people who habitually media-multitask, juggling several streams at once, with those who do not.^[2] The heavy multitaskers performed worse on tests of filtering out irrelevant information and, surprisingly, were worse at task-switching itself. Whether multitasking caused this or simply attracts people already wired that way is still argued. Either way, it punctures the idea that practising multitasking makes you good at it.

Does practising multitasking make you better at it?

No. The same 2009 study found the heaviest multitaskers were worse at switching, not better. The habit trains a scattered style of attention rather than a skilled one.

What should you do instead of multitasking?

25 minutes on a single task is a fine place to start. The alternative is unglamorous and effective: single-tasking in protected blocks.

• One task, one block. Choose a single thing and work only on it for a set stretch. Twenty-five minutes is a fine start.
• Remove the switch triggers. Close the other tabs, silence notifications, and put the phone in another room. You cannot resist a switch you never get prompted to make.
• Batch the small stuff. Group emails, messages and admin into set windows instead of letting them interrupt all day.
• Reframe the feeling. Doing one thing at a time feels less busy. That feeling is not lower productivity, it is the absence of the switching tax.

The pull to do everything at once is, underneath, a discomfort with single-pointed attention, the same discomfort that sends us to our phones in every quiet moment. Sitting with one thing is a skill, and like any skill it returns with use. That is the whole premise of How to Be Bored Again.