I want to play a game. I want you to get up and find something to write with and something to write on. And I want you to find the stopwatch on your phone, or move yourself near a clock.

Ready? Let’s start.

Round one: you have 10 seconds. Within those 10 seconds, I want you to write out the first 12 letters of the alphabet (A-L) as quickly as you can, and then I want you to write out the first 12 numbers (1-12) as quickly as you can. Go!

Done? My guess is that you found that fairly simple and you were either able to complete it all within the 10 seconds or you got incredibly close. Nice work! Now, let’s crank it up a notch.

Round two: again, you have 10 seconds. Like before, you will be writing out the first 12 letters and numbers, except this time, I want you to quickly alternate between the two. So, when the timer begins, start by writing the first letter (A), then write the first number (1), then the second letter (B), then the second number (2), and so on. Got it? Go!

This time, I’m guessing you only made it about two-thirds of the way through. More importantly, even though the tasks weren’t difficult, I’m guessing you also got slightly flustered or confused.

Reader, welcome to the wonderful world of multitasking.

We’re all trying to multitask at the moment. The Covid-19 pandemic means we are trying to balance professional and personal demands in the same space at the same time.

When it comes to education, teachers may well be trying to teach and care for their own children while teaching their class remotely, alongside multiple other demands. Pupils, meanwhile, are balancing the work set with the lure of their phones, the television, their toys, their siblings … and so much else.

Even in more usual times, our obsession with efficiency combined with the all-you-can-eat buffet of social media means we have come to assume that multitasking is possible: speak to any teacher and they will say that teens, in particular, believe it is entirely plausible that you can learn while simultaneously scrolling TikTok, having the television on and eating last night’s pizza.

Sorry to break it to you, but multitasking simply isn’t possible. And the experiences described above that we may think are multitasking - which actually aren’t - are undesirable if we want competent learners.

Let me explain.

To understand multitasking, we first need to quickly come to terms with the constructs of attention filters and task rulesets.

We’ll start with the former. As you’re well aware, attention is a powerful cognitive function that allows us to quickly and effectively sift through the noisy world we inhabit. The best way to conceive of attention is as a filter. Much like those old-fashioned 3D glasses that only allow certain wavelengths of light to reach your eyes, attention allows only relevant information to pass into conscious awareness while blocking out irrelevant information.

This leads to a very important question: what determines whether information is relevant or irrelevant?

This is where rulesets come in. Every task we undertake - be it checking Facebook, doing the banking or going for a jog - comes with a unique set of rules that dictates what actions are required to successfully undertake that task. For instance, in order to successfully read these words now, your “reading ruleset” dictates that you must sweep your eyes left-to-right over each line, hold each sentence in memory until you reach the end of a paragraph, and so on.

When we choose to engage with a task, the relevant ruleset is loaded into a small brain region called the lateral prefrontal cortex (LatPFC). Once a ruleset is loaded into the LatPFC, this ruleset serves to differentiate between relevant and irrelevant information. In other words, task rulesets determine attention filters.

You can think of this process kind of like an old stereo. In this instance, each CD (task) comes with its own unique set of instruments, vocals and melodies (ruleset). Any time you wish to listen to a particular album, you must load the relevant CD into the stereo (LatPFC). Once a CD is loaded, the speakers will broadcast only that album’s instruments, vocals and melodies (attention filter).

Here’s the problem: much like how old stereos can only hold one CD at a time, the LatPFC can only hold one ruleset at a time. This region of the brain is highly specialised, leading to a very strict bottleneck: human beings can only engage with one ruleset, one attentional filter and one task at a time.

In other words, we can’t multitask.

“Hang on,” you may shout, “I chat on my phone while surfing the web. I update my social media while reading. I check emails while at work meetings.”

Yes, you do. But these scenarios are not truly multitasking. If you look closely, you’ll notice that in each of these instances we’re never undertaking two tasks simultaneously. Rather, we’re rapidly jumping back and forth between tasks, quickly swapping out a ruleset and resetting filters each time we do.

Researchers call this process task-switching, and it’s a lot like trying to watch two different programmes on a single television set. Sure, you can quickly flip back and forth between TV channels, but you’re only ever watching one show at a time.

It seems likely that while pupils and their teachers think they are multitasking, particularly during the current school closures, they are actually more likely to be task-switching.

So, is task-switching any more possible than multitasking? Unfortunately, this process incurs three major costs:

1. Time
Task-switching is not instantaneous. Every time we reset our attention filter, there is a brief period called the attentional blink, during which all sensory processing stops. Although this sensory dead zone is relatively short (approximately 0.15 seconds), it occurs each and every time we switch tasks. This is why most people are unable to complete round two of the game we played at the start of this piece: each jump between letters and numbers incurs an attentional blink, meaning that by the time people reach the letter F, they’ve already lost a full second and a half.

2. Accuracy
Task-switching is not seamless. Every time we swap out rulesets, there is a brief period called the psychological refractory period, when the two rulesets blend. If you’ve ever been writing an email while holding a conversation and accidentally typed words you meant to say out loud, you’ve experienced this process. Again, this is why most people get confused during round two of our game: each jump between letters and numbers incurs a refractory period, leading most people to make simple errors.

3. Memory
As we’ve explored in an earlier Tes cover feature, in order to form new declarative memories, information must flow through a brain structure called the hippocampus (“Why where you learn matters”, 6 March 2020). Unfortunately, when task-switching, activity within the hippocampus decreases markedly - a sure sign that memory is being impaired. More problematic, activity increases within the striatum: a brain region linked to subconscious processing and automaticity. This means memories formed while multitasking are often stored as habitual routines, making them incredibly difficult to consciously access in the future.

But maybe you are still not convinced. When people start considering the impossibility of multitasking, a number of common questions arise that are worth quickly exploring here.

‘What about walking and talking?’
Clearly, we multitask every day. We chat while eating, sing while driving and organise work schedules while jogging. If you look closely, however, you’ll notice each of the above examples includes a habitual routine mediated by the striatum (eating, driving, jogging). This means human beings can perform two tasks simultaneously, but only when one task is run on autopilot and can be performed with little conscious thought.

With that said, have you ever been so involved with a conversation that you have forgotten to eat, or been so enthralled with a song while driving that you missed your exit? Even when one task is a habitual routine, this does not guarantee effective multitasking. In fact, even the simple act of walking and talking demonstrates interference. Accordingly, although we can ride a bike and chew gum at the same time, this does not negate the larger multitasking story.

‘Maybe men can’t multitask, but women surely can … right?’
Nope, and shame on you for your sexism.

Although there are individual differences in multitasking ability, these differences do not align along gender lines. This means some people may suffer less than others from multitasking (regardless of gender), but rest assured - nobody does it well.

‘Is multitasking a skill that can be improved?’
When we deliberately practise rapidly jumping between two tasks (say, flying a kite and kicking a ball), we can learn to do the tasks simultaneously. Unfortunately, this has little to do with a general multitasking ability. Rather, the brain will simply learn to pool the kite flying and ball kicking rulesets into a single, large kite/kick ruleset.

In other words, there is no underlying multitasking “competency” to be honed and applied across situations. All multitasking improvements are driven by brain mechanisms building more inclusive rulesets. This means learning to fly a kite while kicking a ball makes us no better at writing emails while holding conversations.

‘Are digital natives better than others at multitasking?’
Unfortunately, there is no such thing as a digital native: an incredible amount of research has demonstrated that children who grow up in a world of computers are no better or worse at utilising technology than anybody else. This means that they are no better or worse at multitasking than anyone else.

Despite this, as mentioned earlier, many students think they’re better at multitasking. But in an odd twist of fate, people who are highly confident in their multitasking ability almost always learn and perform worse while multitasking than people who recognise they’re struggling. High confidence often shields individuals from recognising their own inefficiencies.

‘Does watching TV while doing homework count as multitasking?’
Yep. Aside from some rare instances of stochastic resonance (the idea that injecting noise into a system can actually enhance the function of that system), media multitasking is a real problem.

More than 60 per cent of students admit to engaging with television, internet or smartphones while studying - a practice demonstrated to significantly hinder learning and memory formation.

To make matters worse, when people use a device to multitask while in a group setting (say, checking social feeds while in the classroom), this not only impairs their learning but also the learning of everyone within that person’s immediate vicinity. In other words, media multitasking has a detrimental radius and anyone caught up within it suffers.

So, if multitasking is impossible and task-switching undesirable, how should we set up learning both in and out of the classroom? I will leave you with the following pieces of advice:

1. Don’t open the door to multitasking
This first suggestion seems rather obvious: it’s important that we don’t invite multitasking during learning. Although this sounds easy in theory, it is actually quite difficult in reality. Each time we combine speech and text, display complex figures without explanation or simply mention web addresses, we are encouraging pupils to multitask. To avoid this, it’s important that we’re well aware of our lesson progression and introduce ideas only when there is time devoted to engaging and completing each in turn.

2. Break down projects into smaller chunks
Piggybacking off the above concept, it’s important to explicitly break large projects into small chunks with short deadlines. When presented with a long-term project, most people set their sight on the final product (distal goal). Unfortunately, this has been shown to increase the likelihood of multitasking, which, in turn, delays completion, reduces quality and diminishes confidence. Luckily, when large projects are broken into discrete steps, people can focus on each step in turn (proximal goals) - a practice shown to decrease the likelihood of multitasking, speed up completion, enhance quality and boost confidence.

3. Don’t leave things unfinished
When considering content delivery, it’s important to remember that the human brain is, by and large, an advanced prediction machine. Very rarely does the brain live in the present moment; most of the time it is projecting into the future to predict and prepare for what is coming next. For this reason, whenever the brain comes across an unsolved or unfinished problem, it typically interprets this as a failed prediction that must be corrected. Why does this matter?

Sometimes when teaching, we unintentionally leave ideas unfinished. Maybe we’ll start telling a story only to get sidetracked, or start drawing a diagram only to run off on a tangent.

When information is left incomplete, many people will feel compelled to attempt to complete/answer the unsaid while maintaining focus on the lesson - multitasking in action.

Accordingly, it’s important that we try to remain cognisant of the flow of ideas and avoid leaving things incomplete. The same thing occurs when we give students handouts that contain practice problems or questions meant to be addressed at a later time. Drawn to unsolved puzzles, many people will begin immediately filling in these handouts. Unfortunately, this can easily cause them to miss key information and impair learning. As such, it’s worth teachers holding on to practice questions until it’s time to explicitly address them during the lesson.

4. Limit the use of digital technologies
As you can likely guess, another realm where multitasking rears its head is digital technologies. Students who use a computer for learning typically make it less than six minutes before accessing social media and typically spend 38 minutes of every hour multitasking and off-task. Put simply, technology breeds multitasking - it is built into the very fabric of most devices (just think of smartphones running parallel apps, laptops displaying dozens of internet tabs, and Twitter cycling an unending stream of unrelated content).

When computers are employed inside the classroom, teachers have the opportunity to block internet access, delete programs and focus attention. Unfortunately, when computers are employed outside the classroom, these control mechanisms largely disappear. In these circumstances, the best option is to teach students about the consequences of digital multitasking while offering constant reminders for them to take control of their own digital environment.

This also means that we should consider engaging with digital technologies only when they are integral to the learning task. Decades of research have demonstrated that because digital tools cater to distraction, they, by and large, impair learning. Accordingly, a good rule of thumb is to ditch unnecessary technology and, with it, the temptation for multitasking. If it’s possible to do a lesson or activity live and in person, it’s always a smart idea to do that.

Jared Cooney Horvath is a neuroscientist, educator and author

This article originally appeared in the 22 May 2020 issue under the headline “Could multitasking be ruining your lessons?”