Interestingly, our capacity limitations in these brain regions
are not necessarily ixed. We have known for a long time that
practicing 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 poten-
tial of the human brain. Are we able to expand our capacity so that
we can become super-eicient parallel processors? Or are we
forever hard-wired as slow and steady serial processors? Where
exactly lie the boundaries of our information-processing abili-
ties, and what gains can be made from practicing 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 poten-
tial 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 multi-
task –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 under-
standing 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 diicult 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 unre-
lated to multitasking. We were then able to compare the two
groups to see which brain changes speciically predicted multi-
tasking improvements, and not general factors such as motiva-
tion. 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 compo-
nent tasks. With practice, the neural activity that corresponded
to each task became more distinct.Therefore,inorder 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 aretask-speciic orgeneralise to new tasks? More
speciically, if you practicemultitaskingare 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.
Theevidence for whether multitasking practice will make
you a“supertasker”, or will just make you really good at the task
you practicedon, iscurrently mixed. For healthy young indi-
viduals it appears that practising very simple actions, such as
posting on social media, does not lead to generalisedbeneits.
Although people improve at multitasking those speciic tasks,
they are no better off when they switch to new tasks that are
similar.This is mostlikely because they have not had the oppor-
tunity 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 improveone’s ability to sustain concen-
tration and maintain and manipulate information in the memory.
Thecurrent evidence thus suggests two different methods to
improve multitaskingproiciency.Onone hand, simple prac-
tice ofspeciic behaviourscanlead tobeneits for a speciic multi-
tasking 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 lexibility.Training your brain torespond a given
way to the stop sign decreases the probability that you will act in
different ways the next time you see that sign.
Onthe other hand, engaging in practice tasks that are chal-
lenging, dynamic and adaptive may aid in the development of
more lexible multitasking abilities.
Either way, neither of these methods are likely to lead to bene-
its that willspanthe 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.
KellyGarner is a Postdoctoral Research Fellow inTheUniversity ofBirmingham’s School of
Psychology. Paul Dux is an Associate Professor and ARC Future Fellow atTheUniversity of
Queensland’s School ofPsychology.MAY 2016|| 35“Given the revenue associated
worldwide with the brain training
industry, this truly is a multi-billion
dollar question.”