How the brains of 'super-multitaskers' are different

Human Brains Do Not Multitask Well
Human Brains Do Not Multitask Well

Christian Jarrett for NYMag

Multitasking, we've been told constantly in recent years, is something human beings aren't naturally good at. Even though technology has given us more opportunities than ever before to, say, work while checking in on an NBA score, or have a conversation while sending a text message, such multitasking works against the human brain's natural strengths. When you try to do more than one thing at once, there's an inevitable hit to your performance on all the tasks involved.

That's because it takes cognitive energy to switch between tasks — as I put it in 99U's book on productivity, there is really no such thing as multitasking — there is only task-switching.

Apparently, though, this isn't a universal rule. A small minority of people — Super-Taskers — seem able to multitask without showing the usual loss in performance. Their existence was documented in a paper published five years ago by a pair of researchers at the University of Utah who were interested in whether some people might be better at multitasking than others. To test this, Jason Watson and David Strayer devised a tricky challenge that was meant to simulate driving while on a cell phone. Participants had to keep their car in a lane on a driving simulator while simultaneously memorizing words they heard and solving spoken math problems.

Most people the psychologists tested were much worse at the driving and the mental test when they did the two together than when they did them separately, just as expected. But to the researchers' surprise, five of the participants (2.5 percent of the sample) were able to deftly juggle the tasks without any measurable hits to their performance. These Super-Taskers weren't just better than average at multitasking, they actually broke the golden rule that you can't multitask without your performance going down.

This finding is of huge interest to psychologists for obvious reasons. Imagine the productivity revolution if we could all become Super-Taskers, or at least more like them. The research into these people is at an early stage, but now we know a bit more about what makes their brains different: The latest issue of the psychology journal Psychonomic Bulletin and Review features a new study by Watson and Strayer and their colleague Nathan Medeiros-Ward in which they've tested what happens in the brains of Super-Taskers when they're multitasking.

Five of the Super-Taskers from the original 2010 study took part, plus three others who have since been identified using the driving simulator challenge. For comparison, eight other healthy participants were recruited, matched with the Super-Taskersfor age and working memory, or one's ability to hold information in mind for short spells of time (the researchers wanted to make sure that any differences they observed between the two groups were explainable by super-tasking ability, not something more straightforward).

Lying in the brain scanner, the participants performed a multitask challenge designed to be even more devilishly difficult than the driving simulator. Versions of this task, known as the n-back test, have become a staple of research into mental performance. In this case, the participants had to watch a screen and keep track of the changing positions of a blue square and at the same time (in the multitasking version of the task, but not the control version), they had to listen to and keep track of a stream of letters played over headphones. In the most super-difficult condition, the participants had to indicate when the square's location matched its location three presentations earlier or when the latest letter they heard matched the one spoken three letters earlier (hence the task name "n-back" where n is the number of trials earlier). Essentially, the participants had to divide their attention between what they could see and hear, remember the recent run of locations and letters, and spot whenever there was a relevant match on either audio or visual. You can have a go at a milder version of this challenge via this website, but beware it might make you feel like your head is going to explode.

The research team was particularly interested in a pair of regions at the front of the brain that are known to be involved in multitasking: the prefrontal cortex (PFC) and the anterior cingulate cortex (ACC). Keeping things simple, you might say the PFC is the region that keeps several plates spinning at once, while the ACC supervises and looks out for a plate about to be dropped.

These parts of the control participants' brains heated up under pressure, just like the way your iPhone gets hot when you run too many apps at once. But the key finding is that as the multitasking was made more difficult, the Super-Taskers' brains stayed cool, with reduced activity compared to those in the control group. The researchers say this is likely a sign of their having higher than normal neural efficiency. Note that, disappointingly, the Super-Taskers didn't actually outperform the controls in this study. This suggests that, while their brains reacted differently to the challenge, their mental juggling skills were not limitless.

We need more research to find out what kinds of tasks the Super-Taskers do and don't excel at, and also more studies into the structural reasons for their apparently enhanced neural efficiency – such as, perhaps, having better connectivity between brain regions than non-Super-Taskers. But for now, the new results fit nicely with related findings. Consider a brain scan of the Brazilian soccer star Neymar — a study showed that his motor cortex (that controls movements) was activated less than other professional players when he moved his foot. Similarly, a recent study found that Formula One drivers showed less localized brain activity during visual-spatial tasks compared with control participants. It's not just sporting expertise that shows this pattern. When they play the piano, professional pianists display less than normal brain activity in regions involved in finger control. And last year, a study of elite chess players found they had reduced gray matter in parts of the brain involved in representing relations between objects —again, likely a sign of enhanced neural efficiency.

These recent neuroscience insights suggest we need to rethink intelligence and ability a bit. In pop culture, there's an assumption that bigger brains are better (just look at Marvel Comics' super-genius character Leader with his oversize cranium), and that the secret to greater ability is to use our brains more (consider the "we only use 10 percent of our brain" myth perpetuated in last year's movie Lucy). In fact, what the new findings about Super-Taskers suggest, along with other recent research, is that mental performance and expertise often goes together with reduced brain volume in specific areas, and lower levels of neural activity. In other words, with your brain, as with certain other things, it seems it's not the size that matters, but how you use it.

Dr. Christian Jarrett is editor of the British Psychological Society's Research Digest blog. His latest book is Great Myths of the Brain.

Psychonomic Bulletin and Review