Why Switching Tasks Costs More Than It Seems

Mostly, yes. What feels like multitasking is usually rapid switching between tasks, and psychology research links each switch to lost time and weaker performance. The most practical response is to protect stretches of single-task work, then check whether that changes your own output.

What is task switching, and how does it differ from doing two things at once?

Task switching means moving your attention from one task to another, while doing two things at once would mean running both in parallel. Sophie Leroy, a business researcher at the University of Washington, argues that the second rarely happens: "We just switch back and forth between things really fast, and that is problematic," she says in University of Washington Magazine.

The distinction matters because a switch has a price. Two tasks that feel simultaneous are, in this view, a sequence of handovers, and each handover can cost something.

What did the classic lab studies find about the cost of switching?

They found that switching takes time, and that the cost grows when tasks are harder or less familiar. An American Psychological Association release on task-switching studies reports that participants lost time whenever they had to change from one task to a different one. The same release says time costs increased with task complexity and were greater when people switched to relatively unfamiliar tasks.

The release also offers a mechanism: "Rule activation itself takes significant amounts of time, several tenths of a second," according to the APA release on Newswise. The date of the original studies is not indicated on that page. Separately, the University of Washington Bothell notes that switching attention tends to be difficult and subsequent task performance easily suffers (published 17/05/2024).

Why does part of the mind stay on the previous task?

Unfinished work keeps a hold on attention. The University of Washington Bothell describes research in which attention stays on the interrupted task rather than moving completely to the new demand. It adds that people tend to cling to unfinished work rather than set it down, even when shifting focus is unavoidable.

Leroy compares this to browser tabs: "Like having too many browser tabs open, unfinished tasks stay active in our minds" (University of Washington Magazine). The same piece offers a simple counter-move: putting your unfinished thoughts on paper makes it easier for the mind to disengage and to pick the thread up again later.

Is doing two things at once ever harmless?

Sometimes, but the evidence cited here is narrow. A University of Illinois publication on working with background music states that listening to music while completing tasks is another form of multitasking. Its summary points to one exception: spatial tasks, where music helped performance.

That page does not address podcasts or routine chores such as folding laundry, so no finding is indicated for them. A reasonable reading is that background audio is not automatically neutral, and that the kind of task matters.

How do notifications and interruptions add to the cost?

They add switches you did not choose, and they can cost attention even when ignored. The Association for Psychological Science reports that phones can hurt attention even when the person never touches them. In that research, people who received a message were about three times as likely to make a mistake as those who did not (APS).

A Gallup Business Journal Q&A on workplace interruptions puts numbers on the aftermath. According to the Q&A, interrupted work was resumed on average in 23 minutes and 15 seconds, and 81.9 percent of it was resumed the same day (Gallup Business Journal). It also reports about two intervening tasks before a return to the original one (Gallup Business Journal). People interrupted themselves about 44% of the time, so the habit is not only external (Gallup Business Journal).

What does public research say about single-tasking, time blocking and batching?

The clearest public evidence concerns batching. In a University of British Columbia study, some participants were instructed to limit checking email to three times daily for a week, while others checked as often as they could. In the department's news item of 03/12/2014, the finding is that people felt less stressed when they checked their email less often, and the item also mentions encouraging workers to check email in chunks.

Single-tasking follows from the switching findings above, since fewer handovers mean fewer costs. The pages cited here do not test time blocking directly, so no measured effect is indicated for it. Treat it as a way to create single-task stretches, not as a proven method.

How can a household or small team reduce interruptions without becoming unreachable?

Agree on a few visible rules, and keep one route open for real urgency. The research above suggests where to aim: fewer unplanned switches, and fewer alerts that pull attention even when ignored.

• Set shared check times for messages and email, in line with the chunked checking described by the UBC researchers.
• Use a clear signal for focus time, such as a closed door, a status line or a note on the fridge.
• Name one urgent channel, such as a phone call, for situations that cannot wait.
• Keep phones out of sight during focus time, since the APS findings concern phones that were not even used.
• Never silence contacts tied to safety or health. For care responsibilities, set the rules with the people involved.

How can you test whether focused blocks improve your own output?

Run a simple comparison over two weeks, and treat it as a personal experiment, not a controlled study. The table below links each habit to the finding it rests on, so you can pick the ones that fit your day.

1. Choose two or three measures before starting, such as tasks finished per day, time to complete one recurring task, and how stressed you feel at day's end.
2. In week one, work as usual and record the measures.
3. In week two, protect focused blocks, check messages at set times, and keep a notepad nearby. Leroy's suggestion that putting notes on paper eases the handover fits here: note where you stopped, then move on.
4. Compare the two weeks. Account for anything unusual, such as a deadline or an illness.
5. Keep what helped, drop what did not, and adjust one habit at a time.

Sources

• Is Multitasking More Efficient?, American Psychological Association (via Newswise), consulté le 31/10/2026
• An ongoing study on the success of staying focused, University of Washington Bothell, consulté le 31/10/2026
• There's no such thing as multitasking, according to business expert Sophie Leroy, University of Washington Magazine, consulté le 31/10/2026
• Too Many Interruptions at Work?, Gallup Business Journal, consulté le 31/10/2026
• You're A Distracted Driver Even When You Ignore That Text, Association for Psychological Science, consulté le 31/10/2026
• Checking your email less can help reduce stress, University of British Columbia, Department of Psychology, consulté le 31/10/2026
• Facing the music: performance implications of working with music in the background, University of Illinois, consulté le 31/10/2026