Every time you switch tasks you pay a cost. You’re slower getting going on the new task, you’re more likely to make mistakes, and part of your attention stays behind on whatever you just left, which researchers call attention residue. The costs grow with how complex the tasks are. In lab tasks a single switch costs a fraction of a second, but real work switches cost more, because you have to rebuild the context in your head each time.
You’ll also see a precise claim that it takes 23 minutes to refocus after an interruption. That figure is widely repeated and poorly sourced, and we explain why below.
What is a task switching cost? #
A task switching cost is the drop in speed or accuracy when you move from one task to another, compared with sticking to one.
The classic evidence comes from experiments by Joshua Rubinstein, David Meyer and Jeffrey Evans, published in 2001. People alternated between simple rule-based tasks, like sorting shapes by different rules. Switching cost them time compared with repeating the same task, and the cost increased as the rules got more complicated. It shrank when people got a clear cue about which task came next. The researchers described switching as two stages: shifting your goal, then loading the rules for the new task.
This is why “multitasking” is mostly a misnomer. When both tasks need real thought, like writing an email while listening to a lecture, you’re not doing them at once. You’re switching back and forth quickly and paying the cost each time.
What is attention residue? #
Attention residue is the part of your mind that stays stuck on a previous task after you’ve moved on. The term comes from management researcher Sophie Leroy. In a 2009 paper she found that it was hard for people to pull their attention away from an unfinished task, and that their performance on the next task suffered as a result.
Two practical consequences follow:
- Switching away from something unfinished is worse than switching after finishing. A half-written paragraph keeps pulling at you in a way a finished one doesn’t.
- Quick checks aren’t quick. Glancing at your inbox mid-essay leaves an unanswered message sitting in your head while you try to write.
Do interruptions make you slower? #
Not always, and the answer is more interesting than “yes”. In a 2008 experiment by Gloria Mark, Daniela Gudith and Ulrich Klocke, 48 people answered a set of work emails, sometimes with regular interruptions by phone or instant message. The interrupted people actually finished faster, with no difference in quality. But they paid for it with more stress, frustration, time pressure and effort. They compensated for the interruptions by working faster and harder.
So interruptions may not show up in how much you get done in an hour, but they can show up in how drained you feel at the end of the day.
Is it true it takes 23 minutes to refocus after an interruption? #
We can’t confirm it. The figure, often quoted as “23 minutes and 15 seconds”, is usually attributed to Gloria Mark’s research on office workers. It isn’t a result of her 2008 experiment above, which found interrupted people were faster, not slower. We haven’t been able to trace the figure to a published study that measured refocusing time in a way that supports such a precise number, so we don’t use it.
What Mark’s research does report is how often people switch. On her own site, she says attention on any one screen now averages about 47 seconds. That’s a measure of habit in real offices, and it shows how many switches a typical workday contains.
How much does task switching cost you? #
It depends on the kind of switch. Here’s a rough guide based on the research above.
| Type of switch | What it costs | Example |
|---|---|---|
| A notification you don’t act on | Attention briefly pulled away (Stothart et al., 2015) | Phone buzzes on the desk |
| A quick check, then back | Restart time plus some attention residue | Glancing at a group chat |
| Leaving an unfinished task | Heavier attention residue | Answering email mid-paragraph |
| A full change of context | Time to rebuild the details in your head | Going from a meeting to writing code |
| Frequent interruptions over a day | More stress and effort, even if output holds up | An open-plan office afternoon |
The single biggest factor you can control is how many switches you allow. One switch is cheap. Forty in a morning add up.
How can you reduce task switching? #
- Batch small tasks. Answer email and messages at set times, like late morning and late afternoon, instead of as they arrive. One block of switching beats thirty scattered ones.
- Work in single-task blocks. Pick one task, name it, and set a timer. Work Capy asks “what are we on?” before a session, so each block has one named task, and leaving the app mid-session counts against you: one warning, then the session is forfeit. It won’t stop you switching tasks on your laptop, but it takes your phone out of the rotation.
- Turn off notifications you don’t need. Every alert is an invitation to switch. Use Do Not Disturb or a Focus mode during work blocks.
- Finish the unit before you switch. Complete the sentence, the calculation or the function before you stop. Less is left hanging, so less residue follows you.
- Leave yourself a note. Before a break or a switch, write one line on where you’ll pick up: “Next: check the figures in Table 2.” It’s much faster to restart from a note than from memory.
- Keep a distraction list. When something pops into your head mid-task, write it down instead of doing it. Handle the list at your next break.
For more on protecting long blocks of attention, see our deep work tips and time blocking vs Pomodoro. If you’re already mid-distraction, how to refocus after getting distracted has a short reset routine.
Frequently asked questions #
Is multitasking ever effective? #
When one of the tasks is automatic, yes. Walking while talking or folding laundry while listening to a podcast works fine. When both tasks need real thought, you’re switching rather than multitasking, and you’ll be slower or make more mistakes on both.
How long does it take to refocus after an interruption? #
There’s no reliable single number. It depends on how complex the task is, whether you left it at a natural stopping point, and how long the interruption lasted. Leaving yourself a note on where to resume, and finishing the current unit of work before switching, both shorten it.
What is attention residue? #
It’s the part of your attention that stays on a previous task after you’ve switched away, especially if you left it unfinished. Sophie Leroy’s 2009 research found it made people perform worse on the task they switched to.
Does task switching make you less productive? #
Often, but not always in the way you’d expect. Lab studies show clear time costs for switching between complex tasks. In one experiment, though, interrupted office workers kept their output up by rushing, and paid for it with more stress and effort instead.