Brain + smartphone = 🤯

The presence of your phone impacts your brain capacity more than you think… But there’s a good side in it.

Have you ever questioned the impact of your smartphone over your brain capacity?
Have you ever questioned your dependence to it, and how you would get through your day if it was to disappear?

I bet you have. And it is no scoop if I tell you that, indeed, your smartphone has a huge impact on you. It is known Khaleesi

But no scoop either: humans are particularly good at burying their head in the sand when facts become inconvenient. I do. We all do. And I will probably continue a little longer! But this scientific experiment I read about this week[1] will, eventually force me to change the way I deal with my smartphone everyday. In the study, they call it “The Brain Drain”.

Would you prefer: a notification or a mosquito bite ?

We all have already met this situation: You are talking with someone, or deep-working on something, and while your focus is at its maximum, a smartphone notification pops up. It breaks the silence and draws your attention with a little LED. First thing, you are curious. What could it be? Friend? Event? Work?… Anyway you decide to ignore it.

« Not now » you think.

But when you go back to whatever you were doing, there is this kind of background task now running in the back of your head… You try not to lose attention from your focal task. But still, that notification itches. And as a mosquito bite, you know it is bad to scratch ; but it itches too much ! You know the drill…

What just happened is that while you were only doing task A, your Working Memory Capacity (WMC) — the cognitive system that selects and processes information relevant to your current task[2] — was all dedicated to task A.

When the notification prompted — task B — this WMC was not extended so that you can deal with it. It was divided. The WMC was filled with 2 tasks instead of 1.

And this simple scheme shows the basic statement of cognitive research: we have a limited amount of attentional resources, and occupying these attentional resources reduces the available cognitive capacity.

Other room, pocket, desk

Okay, so smartphones’ notifications are distracting. Still no big news, is it ?

Spicy stuff is coming…

A team of 5 scientists gathered around this questioning: During the life of our smartphones, we actually mostly don’t use it actively. It’s in our bag while we walk. In charge and muted while we sleep. Face down on the table of the bar when we tchat. Or even in the other room when we shower… What power could have our smartphone when it is unused? What is the impact of its mere presence by our side on our cognitive capacities? Is it harmful just because we can feel its presence?

To dig this concern, the team ran a first experiment on 520 students, aged 20 to 22.

These students were separated in 3 groups:

  • 1st group had to leave their smartphone outside the testing room — group « other room »
  • 2nd group had to keep their smartphone in their bag or in their pocket — group « pocket/bag »
  • 3rd group had to put their smartphone face down on their desk, in the testing room — group « desk »

They all had to turn their phone on silent (both ring and vibrate off).

All participants completed 2 tests to measure their cognitive capacity :

  • Operation Span[3]: letters and little math problems appear. You have to memorize the letters and solve the math problems at the same time. Perfect test to measure WMC.
  • Raven’s Standard Progressive Matrices (see picture)[4]: looks like most of the IQ tests that you know. You have to fill in matrices with the most logical colored shape. Perfect test to measure Fluid Intelligence[5]. (Fluid Intelligence describes your ability to solve problems without specific knowledge, culture or skills)

You should take a look at 1 or 2 youtube videos about those tests, so that you can have an idea of their difficulty and trickiness, they’re funny.[3][4]

The results of this first experiment were without controversy : as smartphone salience increases, available cognitive capacity decreases. Okay let’s say it again, but with other words and maybe with the tone of Jack Hall, the climatologist alerting the president in the Day After Tomorrow: “Sir, the more humanity gets close to smartphones, the less cognitive capacity they have…”.

The “desk” group is immediately impacted by the phone presence, because they can see it, right in front of them.

The “pocket/bag” group is less impacted, but still: a part of their attentional resources is allocated to a potential phone call, or text message. Because they know that the smartphone is quite close to them.

The “other room” group is far less or not impacted at all because their smartphone is not within easy reach.

See detailed results here below:

I only regret that this 1st experiment doesn’t go deeper, with the comparison of a 4th group with participants that simply don’t own a smartphone… Do you think that the results of the “Other room” group would have been inferior as well ?


But let’s deal with what we have and transpose this learning in one or two daily situations:

  • This evening you have decided to sit down in front of Openclassroom, in order to finish, once and for all, this “Learn how to dev your own website in HTML/CSS” chapter. Working Memory Capacity is at stake here. It enables you to process information that is relevant to your current task, remember ?
    According to this experiment, your capacity to perform in short-term memorizing the chapter would vary whether your smartphone is on the sofa, completely salient ; whether your smartphone is on the floor, charging — not so far ; or whether you left it in your bedroom.
  • Fluid intelligence enables you to solve a problem without any prior skills, culture or knowledge. You definitely would need it if you were to solve a puzzle with your niece or nephew. Well, let your smartphone on the living room table, and he/she might solve it faster than you !

What if we turned our devices OFF ?

… to be straight? It would not change anything.

This was exactly the point of experiment 2, over 275 participants.

They randomly asked to some of them to turn OFF their smartphone, instead of just letting it in silent mode. It didn’t change anything…

Meaning that just seeing your phone, or just knowing that it is close to you is enough to undermine your attentional resources and your available cognitive capacity EVEN if your phone is turned OFF. We seriously are addicts, fellows!

Wait, are we addicts?

Because the team of scientists also questioned this during experiment 2: participants had to answer a set of 13 exploratory questions about their smartphone dependence. First part were 6 questions were focused on a practical way like: “how much do you rely on your phone to go through your day ?”. Second part of questions was about the emotions: “Does your cell phone make you happy ?”.

As a whole, Smartphone Dependence is indeed strongly related to participants performance during the test. To sum it up, the more dependent you are, the less you will succeed in the test if you can see your phone on the desk. Even further, scientists were able to conclude that if you are strongly dependent to your smartphone, you will get better results than anyone once you are isolated from it in the other room.

Waw ! Would it mean that we could consider that aaaaaaaalll this time that we spend on our smartphone, is only a giant training of our brain, so that we can over-perform by letting it go one day?

To be accurate, the scientists separated the two parts of the questions asked at the end so that we could analyse whether it is more practical dependence or emotion reasons that has more impact on the results.

… and winner is practical dependence ! Indeed, no correlation could be drawn between emotional dependence and participants results. On the contrary, if you consider yourself as practically dependent to your device, you’d better stay away from it if you need all you attentional resources.

A box, to rule them all

What should we do to combat smartphone presence and cognitive capacity undermining ? For me, it will be nothing fancy or deeply tech: a simple wooded box, within my appartement entry, with an inscription “Leave your phone, keep your brain.

On the long run, you can also change your habits. The goal is to reduce the frequency of the stimuli, so that your smartphone appears less than a constantly ringing object.

A few ideas to follow:

  • Within apps, notification management is now a must. But for many, the granularity of the settings is not thin enough to configure them just as you wished. Product Managers should provision time and effort with their product team to integrate a proper notification management system into their mobile apps, so that their users neither churn nor turn addicts because of intense notifying.
  • Notification management is now widely integrated in both iOS 12 and Android Pie, alongside this whole “How much time did you spent on your apps?” features. For Apple and Google, next step could be to set safety standards at the entry of the App Store and Play Store. For example, with this kind of policy, a basic e-business app would have to set all its marketing notifications OFF by default — until the users spontaneously activate them.
  • With Android Enterprise, companies can set “work profiles” on their employees’ devices, so that work related stuff remains separated from the rest. A good way to stay away from work impediments and alerts during the weekend. But employees have limited access to this complex setups, and can’t do anything without full consent and technical support from their CTO. Transparent communication should be made about these options that are often very appreciated from employees. Instead of keeping in mind the old MDM system that blocks everything on the smartphone.
    And also note that Apple doesn’t allow this flexibility on a single device yet.

Resources :

[1] Study:

[2]Working Memory Capacity:

[3]Ospan test:

[4]Raven’s Progressive Matrices:

[5]Fluid intelligence:

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