Deep work vs shallow work

The individual of the 21st century is the born multi-tasker. She’s used to instant massagers, podcasts and TV. She’s listening to something while making her dishes, checks her emails while working on a presentation and texts on her smartphone while watching TV. She’s in constant stress, but everything else drives her crazy. She’s convinced that she can handle multiple things at the same time. Her reflexes and perception work much quicker and better. She’s able to cope with several projects on one single day. She’s a true 21st century workaholic. Or so she thinks.

The common belief is that multitasking makes you more productive, that multi-taskers are more talented and that women are the better multi-taskers, yet science suggests otherwise. Multitasking makes you unproductive. It slows you down, increases the rate of your mistakes and reduces your ability to process information. Moreover, it changes the structure of your brain, resulting in decreased cognitive control performance and less socio-emotional regulation.

One study in particular assesses students’ perspectives on multitasking. Every student believed that they frequently multitask, that multitasking increases their productivity and that there are differences in gender. Only the first of those assumption is true. The study clearly demonstrated that students performed much worse if they multitasked. The book ‘The One Thing’ lists several more studies, one of them focusing on multi-taskers and single-taskers perception on productivity. Multi-taskers believe they are much more productive than single-taskers, but are indeed heavily outperformed by them. They scored worse on almost every single aspect.

The idea is that you can do two things at once. But you cannot focus on two things at once. Daniel Kahneman describes in his book ‘Thinking, Fast and Slow’ that there are two systems in our brain, which he calls System 1 and System 2. System 2 is slow and logical and is used when we solve a difficult math task for example. System 1, on the other hand, is quick and intuitive and is used when we walk, talk or do any other automated task. While we can do several intuitive tasks at the same time, our System 2 requires full attention. Think of driving a car: Both driving and talking is an intuitive task, so you can do both at the same time. But suddenly, something unexpected happens. Your System 2 requires your full attention. In the lucky case, you stop talking and handle the situation well. In the worst case, talking occupied so much of your brain power that your System 2 wasn’t able to react quick enough. This is why multitasking fails: Knowledge Work as described by Peter Drucker, i.e. work that requires us to code, manage, organize or think in general, requires our System 2. It’s neurologically impossible to multitask!

System 1 and System 2

Well, almost: It’s neurologically impossible to multitask with two System 2 tasks. That means: Never do your mails while creating a power point presentation. Never check your phone while studying. Never switch between two tasks of cognitively stimulating work simultaneously. However, you can listen to an audio book while doing the laundry. You can check your phone while walking on an empty street. You can fill in excel sheets while listening to music. That is because all of those involve at least one light-weight System 1 task.

Remember that your brain only has space for one of those tasks. If you have ever noticed that you have no idea where you put your keys because you listened to a podcast while coming home or had your thoughts somewhere else, this is because your System 2 was occupied with another task. If I tidy my room, for instance, I refrain from listening to an audio book. I did so in the past and had my room tidy eventually, but could never remember where I put the stuff I tidied up. On the other hand, if I had a system to put everything at one place exactly when tidying up, a place that would never change, I would be able to multitask while tidying up. The level of automation will determine whether you will be able to add another cognitively demanding task. The recipe is fairly simple: The moment you need conscious focus to do something, your System 2 is at work and multitasking is a bad idea.

Zeigarnik Effect

Bluma Zeigarnik, a psychologist, was always fascinated by how well waitresses could remember her orders even though their groups of customers consisted of a large number of people. It was even more fascinating to her, though, that those waitresses completely forgot the order, sometimes even the faces of the people who ordered, a few minutes after the guests had left the restaurant. How can their memory be so good and bad at the same time?

Eventually, Zeigarnik discovered that we can memorize uncompleted tasks much better than completed ones. This is called the ‘Zeigarnik Effect’. The idea is quite practical and very sound from an evolutionary perspective. Since completed tasks are usually not important anymore, it makes sense to forget them to make room for new, fresh and more important memories.

The Zeigarnik effect rose to popularity because of its seeming practicality for studying. Many study techniques hence exploit the technique by suggesting to not complete a certain memorization task. It is expected that the learned material would then pop up more often in our minds, which is supposed to help us better memorise the desired subject. Yet, those positive effects are not proven scientifically at all. Furthermore, from a logical perspective, the question remains: Once the list is completed then — will the mind forget everything anyway? There is no doubt this practice makes it to the list of ‘Unlimitix’ top 10 bullshit practices’ — and we can highly recommend you do not apply this trick when studying. Finish your subjects, and don’t use this as an excuse to half-ass everything.

The positive effects of the Zeigarnik Effect stem from an opposite logic. Since uncompleted tasks pop up in our heads all the time, they distract us from what we want to do right now. Roy F. Baumeister, for example, has found that people performed much worse in solving puzzles when they had to remember a list with tasks they needed to complete after solving the puzzles.

The one exception: David Allen’s Two Minute Rule. If a task comes to mind and you can finish it within two minutes of time (e.g. an email that only requires a yes/no for an answer) do it straight away.


  1. Focus: Multitasking is stupid for knowledge work. The more time you’ll dedicate to being focused a day, the fitter your brain will be, the happier you will be and the more you will get done. Focus is the key principle of every successful individual. If you haven’t made this your habit, I highly recommend you do so. At the end of every working day, I plan my next day and make sure that I have at least 4 hours of focus. This is especially important if you are getting things done and will remain important when you have switched to being a full-time manager. You will still have to review the codes, designs, and texts your employees produce.
  1. Multitask smartly: In very rare cases, multitasking is indeed possible. If a task is 100% automated, try to be more productive by listening to an audio book or a podcast simultaneously. If you’re not yet doing this, I can highly recommend you do so. Doing laundry, washing dishes and commuting somewhere can take up more than 15 hours a week. This translates to 3 audio books, if you’re listening at twice the speed. You might become an expert on topics you haven’t even studied, just by adhering to this principle.
  1. Use the Zeigarnik Effect to become more productive. The more you get used to this, the less conscious it will be for you to incorporate distractions on your to-do list. Before every session of deep work, prepare a list with all to do’s for this week and for today. If any task comes to mind, distracts you and would take more than 2 minutes to complete, put it on the list.