In this article6 sections
Multitasking feels productive. You’re busy, things are moving, nothing is waiting. The trouble is that feeling busy and getting things done are not the same thing.
What the brain is really doing
When two tasks both need your attention, such as writing an email and following a conversation, the brain doesn’t run them side by side. It switches between them, often several times a minute. Psychologists call this task switching.
Each switch has two steps, described by researchers Joshua Rubinstein, David Meyer and Jeffrey Evans in 2001:
- Goal shifting: deciding “I’m doing this now, not that”.
- Rule activation: putting away the rules for the old task and loading the rules for the new one.
Each step takes only a fraction of a second. But you pay it every time you switch.
What switching costs
In the 2001 experiments, people alternated between tasks such as solving maths problems and sorting shapes. They lost time on every switch, and the loss grew when the tasks were more complex or less familiar.
Individual switches cost little. Across a working day of constant switching, the total can be large. David Meyer has estimated that it can use up as much as 40% of someone’s productive time. That figure is his estimate, not a measurement from the experiments, but it gives a sense of scale.
Switching also causes more mistakes, and it leaves a trace: part of your attention stays on the task you just left, so for a short while you’re not fully on the new one.
Multitasking feels faster because you are busy the whole time. It is the switching, not the work, that fills the time.
Why practice doesn’t fix it
It would be reasonable to think that people who multitask all the time get good at it. A Stanford University study in 2009 found the opposite. People who regularly used several kinds of media at once were more easily distracted by irrelevant information than those who rarely did. They even did worse on a test of switching between tasks.
The study couldn’t say whether heavy multitasking causes this, or whether easily distracted people are drawn to multitasking. Either way, lots of practice didn’t make them better at it.
The rare exception
In a University of Utah driving-simulator study of 200 people, almost everyone drove worse while doing a demanding memory task at the same time. About 2.5% showed no drop at all. The researchers called them “supertaskers”. They are rare, and most people who believe they’re good at multitasking are not among them.
Where it gets dangerous
Driving is the clearest example. In another University of Utah study, people talking on a phone missed twice as many simulated traffic signals as when they weren’t, and reacted more slowly to the ones they did notice. It made no difference whether the phone was hand-held or hands-free. Listening to the radio or an audiobook did not have the same effect.
The problem is attention, not hands. A conversation pulls the mind away from the road.
When multitasking is fine
Combining tasks works when at least one of them is automatic and needs little thought:
- folding laundry while listening to a podcast
- walking while talking
- cooking a familiar meal while chatting
It stops working when both tasks need the same kind of thinking, especially language. That is why reading messages while listening to someone means you take in less of both.
How to do one thing at a time
- Work in blocks. Set aside a stretch of time for one task. Even 25 minutes helps, which is the idea behind the Pomodoro Technique.
- Group similar small tasks. Answer messages in two or three set sessions instead of all day. Our guide to time blocking shows how to fit this into a busy day.
- Turn off alerts while you focus. Each notification invites a switch, even if you don’t act on it.
- Keep one thing on screen. Close extra tabs and put your phone out of sight.
- Write down interruptions. If a thought or a request arrives, note it in a line and return to it later.
- Finish or park. Before switching, reach a stopping point or write down the next step. It makes coming back much quicker.
Frequently asked questions
Are some people naturally better at multitasking?
A small number seem to be, around 1 in 40 in one study. For everyone else, including people who feel confident about it, doing two demanding things at once makes both worse.
Is listening to music while working multitasking?
It depends on the music and the work. Familiar or instrumental music often sits in the background for routine tasks. Music with words tends to compete with reading and writing, because both use language.
Is it true that people can’t multitask at all?
Not quite. People can do two things at once when one is automatic. What we can’t do well is give full attention to two demanding tasks at the same moment.
Sources and further reading
- Rubinstein, Meyer and Evans: Executive control of cognitive processes in task switching, Journal of Experimental Psychology: Human Perception and Performance (2001)
- American Psychological Association: Multitasking, switching costs
- Ophir, Nass and Wagner: Cognitive control in media multitaskers, PNAS (2009)
- Watson and Strayer: Supertaskers, profiles in extraordinary multitasking ability, Psychonomic Bulletin & Review (2010)
- Strayer and Johnston: Driven to distraction, dual-task studies of simulated driving and conversing on a cellular telephone, Psychological Science (2001)
