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Generation Multi

Credit: Kaspars Grinvalds/adobe

Credit: Kaspars Grinvalds/adobe

By Kelly Garner & Paul Dux

As technology continues to become more richly embedded in our daily lives, so too comes the increased demand and temptation to multitask. But can we improve our ability to do two things at once?

How many times have you attempted to multitask today? Did you check your emails while ordering your morning coffee? Or update your social media status while listening to the news?

We have long known that engaging in two tasks simultaneously, even if they are simple, negatively impacts the performance of the component tasks. For example, conversing on a cell phone while driving can impair performance as profoundly as driving under the influence of alcohol.

Frequent engagement in multitasking renders us vulnerable to distraction, and can disrupt learning in the classroom. In addition, our ability to multitask deteriorates as we age, and is strongly impacted by neuropsychiatric injury or disease.

Thus, whether for safety, learning or health, understanding the benefits and shortcomings of multitasking is of significance yet remains poorly understood.

In order to multitask successfully, we depend on the co­ordinated function of the frontal, parietal and subcortical regions in the brain. Our frontal and parietal regions are incredibly flexible information processors whose function is to coordinate and prioritise all of the little tasks we perform in order to meet our many daily goals. Disruption of these brain regions causes problems in the mental functions that we need to successfully navigate daily life, such as keeping a shopping list in mind, maintaining concentration on the road, or deciding not to drink that second glass of wine because the two from the night before didn’t help the next morning.

In contrast, our subcortical brain regions are crucial for us to form skilled or habitual behaviours. Lesions in these areas will affect how well we acquire or execute skilled behaviours.

But there is a cost to this flexibility: capacity. Since frontal and parietal brain regions are involved in the execution of all these useful mental functions, they are also in high demand. This means that while your frontal and parietal neurons are busy focusing on the email you just received on your phone, they are unavailable to decode the words that were just addressed to you in your ongoing conversation. This can lead you to fail to perceive what was said, or delay your response until after you’ve finished processing the email.

Interestingly, our capacity limitations in these brain regions are not necessarily fixed. We have known for a long time that practising constituent tasks can improve our ability to complete them in a multitasking context. If this was not the case we would never achieve walking and talking at the same time. Practice can even help us to multitask some sophisticated mental behaviours, such as making two decisions concurrently.

This poses some interesting questions regarding the potential of the human brain. Are we able to expand our capacity so that we can become super-efficient parallel processors? Or are we forever hard-wired as slow and steady serial processors? Where exactly lie the boundaries of our information-processing abilities, and what gains can be made from practising multitasking?

To answer these questions, we need to understand the neural changes that underpin multitasking improvements. This will help us to understand not only the potential, but also the potential limitations, of practising multitasking.

Recent work in our laboratory has provided some new clues. We already know that we all vary largely in our ability to multitask – we’ve all sat next to someone who seems to have a day’s work done by 10 am. And we all vary in how much practice can improve our multitasking performance. Therefore, we reasoned that understanding how an individual’s brain function predicts their ability to improve at multitasking may be the key to understanding how the brain solves the multitasking problem.

This is a different approach to most brain imaging studies, which typically seek to understand the function of an “average” brain. However, the challenge of our individualistic approach is that we need to examine the brains of a far larger number of people than if we were looking at how an average brain works. This is because the effects that drive individual differences can be more subtle, making them more difficult to detect with smaller sample sizes.

To make inferences about the average brain, we typically examine the brain function of around 15–25 people. In order to understand how individual differences in brain function related to multitasking improvements, we calculated that we needed to examine the brains and behaviour of 100 people.

So we asked 100 people to complete a simple multitask in an MRI scanner. Half of these individuals practised the multitask over a few days, while the other half practised a simple task unrelated to multitasking. We were then able to compare the two groups to see which brain changes specifically predicted multitasking improvements, and not general factors such as motivation. What we found provided an answer for how neurons that get recruited to do many things may learn to do more than one thing at a time.

Improvements in multitasking were predicted by the degree to which frontal, parietal and subcortical brain regions showed dissociable patterns of activity in response to each of the component tasks. With practice, the neural activity that corresponded to each task became more distinct. Therefore, in order to achieve multitasking, the brain may employ a divide-and-conquer strategy by reducing overlap in which neurons are recruited to deal with the two tasks.

So what does this tell us about whether gains from practising multitasking are task-specific or generalise to new tasks? More specifically, if you practice multitasking are you suddenly going to become a productive multitasker in your daily life? Given the revenue associated worldwide with the brain training industry this truly is a multi-billion dollar question.

The evidence for whether multitasking practice will make you a “supertasker”, or will just make you really good at the task you practiced on, is currently mixed. For healthy young individuals it appears that practising very simple actions, such as posting on social media, does not lead to generalised benefits. Although people improve at multitasking those specific tasks, they are no better off when they switch to new tasks that are similar. This is most likely because they have not had the opportunity to generate a specialised neural response to the new task.

However, other evidence suggests that among older people, where the multitasking load is continuous and dynamic, more complex training may improve one’s ability to sustain concentration and maintain and manipulate information in the memory.

The current evidence thus suggests two different methods to improve multitasking proficiency. On one hand, simple practice of specific behaviours can lead to benefits for a specific multitasking scenario by making behaviour habitual. Such practice makes sense in a variety of situations. For example, we want to habitually press our foot down on the brake when we see a stop sign regardless of what else we are doing at the time.

However, the trade-off for gaining habitual behaviours is a decrease in flexibility. Training your brain to respond a given way to the stop sign decreases the probability that you will act in different ways the next time you see that sign.

On the other hand, engaging in practice tasks that are challenging, dynamic and adaptive may aid in the development of more flexible multitasking abilities.

Either way, neither of these methods is likely to lead to benefits that will span the myriad of scenarios we might encounter, such as unexpected incidents on the road. Practised or not, talking on your mobile phone while driving remains a bad idea.


Kelly Garner is a Postdoctoral Research Fellow in The University of Birmingham’s School of Psychology. Paul Dux is an Associate Professor and ARC Future Fellow at The University of Queensland’s School of Psychology.