The Science of Multitasking & What to Do About It

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In 1965, the first published use of the word “multitask” appeared in the context of computing – describing the capabilities of a computer to process several tasks, or computer jobs, concurrently.

In computing, multitasking does not necessarily mean that multiple tasks are executing at exactly the same time. In other words, multitasking does not imply parallel execution, but it does mean that more than one task can be part-way through execution at the same time and that more than one task is advancing over a given period of time.

Even on multiprocessor or multicore computers, which have multiple CPUs/cores so more than one task can be executed at once (physically, one per CPU or core), multitasking allows many more tasks to be run than there are CPUs.

Multitasking solves the problem by scheduling which task may be the one running at any given time, and when another waiting task gets a turn. The act of reassigning a CPU from one task to another one is called a context switch; the illusion of parallelism is achieved when context switches occur frequently enough.

And then, the term “multitasking” has since been applied to human tasks.

Human VS Computer

Most people define professional capability by the ability to multitask. And most companies are hiring and advancing their employees based on their ability to complete multiple tasks at the same time too.

This ability or skill is overrated when everyone is obsessed with getting more done in less time. The truth is, it does more bad than good to the performance and productivity of an individual and even organization.

But what really is human multitasking? Is there any different from computers?

It actually works the same way in computing. Most of the time, multitasking is an illusion, we’re tricking ourselves to believe we’re handling many tasks at the same time, but what we are really doing is simply switching from one task to another, back and forth, during that given period.

Why? Because our brain simply can’t handle more than two mentally complex tasks at the same time (it’s definitely fine if you’re walking and talking at the same time).

In a recent study, scientists at the Institut National de la Santé et de la Recherche Médicale (INSERM) in Paris discovered this when they asked study participants to complete two tasks at the same time while undergoing functional magnetic resonance imaging (fMRI).

When the scientists told the group they would receive a larger reward for accurately completing one of the two tasks, they found that nerve cell activity increased in only one side of the prefrontal cortex. However, when the greater reward was associated with the other task, the other side became more active.

The findings suggest that when there are two concurrent goals, the brain divides in half, says INSERM neuroscientist Etienne Koechlin, who led the study.


When the scientists asked the study participants to attempt yet another task, they found that the participants regularly forgot one of the three tasks they were asked to perform. The participants also made three times as many errors as they had made when attempting only two tasks. Koechlin says the study demonstrates that while we can readily switch between two tasks, we “might be in great trouble when we try to juggle more than two tasks, simply because we have only two frontal lobes.”

Cost of Context Switch

You might now think: “Okay, it’ll be fine as long as I don’t handle more than two tasks at once. It’ll still increase my productivity compared to doing one thing at a time, right?”

No. Multitasking actually does more bad to productivity than good.

In order to determine the impact of multitasking, psychologists, Robert Rogers and Stephen Monsell, asked study participants to switch tasks and then measured how much time was lost by switching. In their study, participants were slower when they had to switch tasks than when they repeated the same task.

Another study conducted in 2001 by Joshua Rubinstein, Jeffrey Evans and David Meyer found that participants lost significant amounts of time as they switched between multiple tasks and lost even more time as the tasks became increasingly complex.

Multitasking is managed by what are known as mental executive functions in the brain. These executive functions control and manage other cognitive processes and determine how, when and in what order certain tasks are performed.

According to researchers Meyer, Evans, and Rubinstein, there are two stages to the executive control process.

  1. The first stage is known as “goal shifting”: deciding to do one thing instead of another.
  2. The second is known as “role activation”: changing the rules for the previous task to rules for the new task.

Switching between these may only add a time cost of just a few tenths of a second, but this can start to add up when people begin switching back and forth repeatedly.

This might not be that big of a deal in some cases, such as when you are folding laundry and watching television at the same time. However, if you are in a situation where safety or productivity are important, such as when you are driving a car in heavy traffic, even small amounts of time can prove critical.

Negative Impact of Multitasking

To make it clearer, below are a few points about what the studies above really means:


Multitasking reduces performance and productivity. While most people think multitasking means getting more done in a shorter period of time, the truth is exactly the opposite. As mentioned above, multitasking simply means switching back and forth between two or more tasks on hand (in head), it’s not a parallel process and execution.

It slows you down to get back on track by gaining the memories and action steps of one particular task you put aside. This cognitive switch occurred switching between tasks is going to make the brain works harder compared to focus on one task at a time. Besides, switching between tasks also leads to more mistakes and errors made.

Multitasking reduces the ability to stay focus. As the habit of multitasking built up, you will find yourself very hard to stay focus. Our brain used to shut off (or ignore) certain senses/information to reduce the workload while focusing on doing something. By involved in multitasking frequently, your brain starts to get confuse with which signal to ignore.

This may be helpful for our ancestor to survive, by having a wider and higher sensitivity with the surrounding – to keep them safe from the wild. But at the era of information overload and media abundance, highly sensitive senses may cause a serious issue on staying focus, and thus lower the performance and productivity.

Multitasking kills your willpower. How does this happen? First, multitasking divides your focus on an important task on hand – it slows downs your decision-making and critical thinking process. Besides, it wears out your brain faster. As your brain get tired, so as your willpower.

This will lead to a bigger (negative) impact with the snowballing effect. With lower willpower, you’re getting less thing done and that directly create the destructive emotions inside you. And thus, these emotions are further draining your willpower.

Harnessing Your Focus

So, how to get away from the habit of multitasking and go single-tasking, or simply reduce it to the minimum level? To go single-task, you simply need to train your focus.

#1 – Do important thing first in the morning. Plan a to-do list a day before and do the most important thing first in the first few hours of the day. This helps you to spare up spaces in your head throughout the day.

With that, you don’t need to switch back and forth between tasks and have a clearer focus on each task at hand.

#2 – Avoid distractions by getting away from distractions. As we train ourselves to be good at multitasking, we’re losing our ability to stay focused. It may be hard to get straight back to single-task behavior when we’re easily getting distracted. So, what’s the best way to not get distracted? Stay away from distractions.

  • If you find yourself always get distracted by your phone while you’re working, shut off your phone until you’re complete with the task on hand
  • If you can’t resist the temptation to snack while you’re on your diet, don’t buy and store any snacks at home.
  • If you find you always caught up on Facebook newsfeed or Youtube recommended videos, block them (check the footnote below for suggested Chrome extensions)

#3 – Establish a schedule to think long term regularly. To stop multitasking, you need to start thinking long term. Most heavy multitaskers don’t do that; they’re confused about what’s important and what’s urgent in their life. That’s why they thought they need to get everything done at the same time.

Thinking long term will helps you to have a clearer vision for the moment. Knowing what’s important to your right now and right here, then put your full focus on it.

#4 – Take real and regular rest. When I say about real rest, it’s REAL rest. Get your head away from work or any task on hand for a certain period of time. Allowing your brain and body to rest will helps them to stay focus and concentrate at work.

I strongly recommend you to use the Pomodoro technique for short frequent rests during a small task (that can be completed within hours), and always take at least ONE day rest within a week (when you’re focusing on bigger task/goal).

Besides some breathing exercises and short meditation sessions, there is one best method to rest for recovery, that most people overlook: Sleep. So, let’s get enough sleep.

For Employers: Reduce Multitasking at Work

Clearly, the (negative) impact of multitasking does not only affect our personal life, but to businesses, teams and organizations too. The cost of the cognitive switch is directly affecting the productivity of an organization and profit.

Employers and managers should take the responsibility to reduce multitasking at work in order to increase the overall productivity and performance. Below are a few strategies you can start apply for your business or organization:

Reduce the number of open projects. Try not to get into a new project before an old project is completed, make an effort to focus and complete any existing open project first.

Reassess and evaluate the capability of the team on the numbers of projects can handle without the need of multitasking. This will help to ensure a high level of productivity being achieved with the ability to deliver quality work at the same time.

Start a project with sufficient preparation. One of the main reasons of an organization suffering from multiple open projects is the lack of preparation. They start a new project without sufficient information, authority, and planning, and then they get stuck halfway without knowing what to do next. Worse, get into next project without solving the first problem completely.

Prepare and plan well is a critical move for any organization to improve their productivity and performance. Make everything clear and collect any necessary resources you need before you start a new project.

Establish a priority system. Clearly, there’s no way (or very little possibility) for an organization to focus on only one thing, especially for new startups and small teams. One best way to solve this is by establishing a priority system. Allow every team members to be clear on what’s the most important mission/task for the company as a whole in that moment, and what’s the most important role/task as each individual for that day or week.

Start Single-tasking Now

It’s definitely fine for us to opt for multitasking once a while when required. But let’s take a deeper look into your personal and professional life, ask yourself:

Is multitasking actually helps in this area of my life?

What happens if I do it with the opposite approach (focus)?

Give it a try, apply those strategies to you personal and professional life, to your fitness routine and your team management. Let’s break from the habit trap of heavy multitasking. Let me know if it helps.

Share this if you find this useful. Much appreciated and thanks!


  1.  “Multitasking” is first used to describe the capabilities of IBM System/360. You can read more about computer multitasking here and about IBM System/360 here.
  2.  The source of researches about “multitasking split the brain” and “switching cost”.
  3. I used to get distracted very frequent by Facebook and YouTube. Until I found 2 Chrome extensions to hide my entire Facebook newsfeed and the entire YouTube sidebar – Newsfeed Eradicator and DF YouTube. If you’re using Chrome, download them, thank me later!

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