What Happens to Your Brain When You Switch Between Tasks?

Imagine you were sitting in a bustling coffee shop and reading this article. If you were to pay attention, you would definitely notice that the level of attention you would need to read this article would depend on the amount of noise others in the cafe are making. If it’s noisy, then you would really have to concentrate, and if it wasn’t, then you would easily read it.

Imagine that someone is not able to prioritize this task of reading, and they keep going back and forth. What would it look like for them? They would constantly be drifting in and out. Maybe their brain might check out for a few minutes and focus on the conversation around them. Maybe they would get distracted by the notification pings of their phone. All of this drifting may even make them forget what they were reading in the first place. 

This is what we call task switching, and it might just look like this for all of us in our daily lives. It might seem harmless usually. I mean, you’re just focusing on some important things and then returning back to your task, right? Isn’t a busy life all about multitasking? The modern overworked world may glorify multitasking, and try as they might, research has shown that multitasking is not always a good thing. In this blog, we get into our multitasking brains, talk about task switching, and help you understand the cognitive repercussions that come with juggling too many things. 

Related: Why Multitasking Makes You Less Productive

What is Task Switching?

Task switching is when you move from one task to another, for e.g., when you decide to answer your emails instead of reading this article. It can happen when you go from writing to returning messages, studying to checking Facebook, or a meeting to a spreadsheet. People often “multitask” by quickly switching between two difficult tasks instead of doing both of them all the way through at the same time.

It may seem simple enough on the surface level, but it isn’t so clean-cut when you look at your brain. I mean, if you’re just checking your texts, then it’s just a small interruption. Your brain doesn’t think of this as a small interruption. It needs to change its focus, get a new goal, update its working memory, stop doing the last job, and choose a new set of responses. These small changes can have a major effect on a person’s efficiency.

And every turn costs a little. Researchers call it the switch cost, and in lab tests it shows up as slower responses and more mistakes right after a change of task. A few hundred milliseconds sounds like nothing. Then multiply it by a hundred switches. Then by a whole week. This can greatly eat up your efficiency and lead to a productivity loss. You might think you’re being efficient, but that’s not true when you look deeper. 

The Science Behind Task Switching

When the brain moves from one job to another, it has to put the old rules down and pick up new ones. Say someone has been checking numbers and then has to write a warm reply to a customer, then it’s a totally different mode. That handoff is a kind of cognitive switching, and it isn’t free, even when it feels instant.

A lot of the heavy lifting seems to happen in the prefrontal cortex, the front part of the brain that deals with planning, deciding, and keeping rules in place. It’s also tied to goal shifting, which is basically the brain telling itself the target is different now, so start aiming somewhere else.

Meanwhile, working memory load creeps up. The details of the first job are still sitting there, half-held, while the details of the second job are trying to move in. It’s like carrying groceries and then getting handed a coffee. Something gets dropped, or at least gripped less tightly.

Nobody feels any of this happening, which is probably why it’s so easy to shrug off. There’s no alarm. No little pop-up saying the brain just spent extra energy on a handoff. It just quietly happens, dozens of times before lunch, and the only evidence is a vague sense of being behind.

The Problem of Attention Residue

Sophie Leroy, a business school researcher, published a study in 2009 that gave the lingering bit a name: attention residue. What’s attention residue, you ask? Sometimes the task you were doing before you decided to switch doesn’t completely leave your brain the way you might assume it does.

Leroy put forward that the previous tasks you left unfinished might still be occupying your brain long after you have moved on to the other. This can make it harder to do well on the next task. This effect is especially important when the first job is still unfinished and fresh in your mind.

The brain keeps that loop open, a bit like a browser tab that’s playing audio and nobody can find which one. So the second task gets a smaller share of the mind. And if that second task is hard, it shows in the individual’s performance, which might be slower and have more errors. Both of your tasks might have been manageable, but the cost of cognitive switching might drain you. 

Mental Fatigue That Comes With Task Switching

Every reset, every reorientation, burns a bit of energy. Add up enough of them, and the result is mental fatigue that doesn’t come from any one hard job, just from the constant restarting. The person ends the day wrung out but can’t quite point to what got finished.

Gloria Mark, who studies interruptions at UC Irvine, has reported that getting back into a task after being interrupted can take something like twenty minutes. Maybe less for easy work, probably more for tangled work. Even if that number is generous, the pattern holds: the trip back is slower than the detour.

Context switching gets underestimated in offices and home setups alike. A five-second glance at a notification looks tiny on a calendar but doesn’t look tiny to the brain.

That gap between what a switch looks like and what it actually costs is probably where most of the hidden productivity loss lives. Not in the big meetings, but the hundred little hops in between.

A morning of heavy switching between your tasks can leave the afternoon already compromised before the first afternoon distraction even shows up. That might explain the 3 p.m. slump better than lunch does, or at least as well.

Related: What Causes Mental Fatigue And How Can You Prevent It

Is Switching Between Tasks Always Bad?

Not exactly. Some switching can’t be avoided. Jobs come with interruptions, kids need things, and managers ping at odd hours. Nobody lives inside a sealed tunnel of focus, and trying to would probably make life worse.

Then again, a quick hop between two easy, routine jobs probably costs very little. Sorting mail and then filing a receipt isn’t going to wreck a brain. The trouble seems to start when one of the jobs is demanding or when the hops happen constantly and without any plan.

There’s also this odd finding that comes up in some research: people who switch the most, and who feel best at it, aren’t always the ones who handle it best. Confidence and performance don’t always travel together. 

Ultimately, task switching that happens on purpose, at a natural stopping point, is a different animal from switching that gets dragged in by a ping.

A Sustainable Approach to Switch Tasks

Nothing here is a hack. It’s just a bunch of things that might help reduce the leftover drag. The easiest way to cut down on task switching is usually to make the stopping points obvious, so leaving a job feels finished instead of abandoned.

Batching similar jobs together helps, since the brain keeps roughly the same rules loaded. Finishing the sentence before walking away helps too, or jotting a quick note about where things stopped, so the loop feels closed instead of hanging open. Muting non-urgent alerts for a stretch, maybe forty-five minutes to an hour, sometimes more. Putting the phone in another room can also always work.

Some people swear by checking messages at fixed times instead of all day. Others find that stressful, because waiting to check feels worse than checking. Both are fair since it probably comes down to the kind of job and the kind of boss.

And the goal isn’t zero switching. That’s not realistic. The goal is fewer switches that nobody chose. So, the next time a workday feels busy but strangely empty, it might not be a lack of effort at all. It might just be a lot of small resets adding up quietly.

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