“Practice makes perfect.”

It’s that favorite mantra of parents, teachers and coaches all around the world. It’s been drilled into our minds since before we could remember.

It makes perfect sense too: If you want to master something, you need to devote some time and effort to it. But, in this day and age, it seems like there’s just so much to do and so little time to get everything done.

So what better way to make use of time than to be able to kill two birds with one stone? With the entire obsession we put on our efficiency, nothing paints more of an impressive picture than effectively getting two things done at once.

Following the wave of technology, which mobilized information, communication and productivity to unprecedented levels — multitasking has now become the cultural norm. It’s the person who seemingly manages to juggle endless loads of work effortlessly who elicits admiration, serving as a source of inspiration for everyone else.

Clifford Nass, a Stanford professor, was among those fascinated by how multitaskers were able to seemingly do so many things at once. He devised a study that pitted proud multitasking aficionados against their single-minded counterparts to learn exactly what was so special behind the minds of the multitaskers.

Nass attributed effective “multitasking” to three abilities: filtering relevant information, managing working memory and switching between task requirements.

He measured these three components individually, using a simple visual cue recognition test, hoping to identify which of these abilities were most heightened amongst the serial multitaskers.

What ensued was an embarrassing sweep. The heavily practiced practitioners were bested at their own game by the newcomers on all three counts! Not only did all their devotion for this fine art do nothing for them, it actually made them far worse at it.

It turns out that that the age-old advice of practice makes perfect has one notable exception: multitasking.

The truth behind the matter is that multitasking, in its true sense, doesn’t exist. It’s impossible to simultaneously work on multiple tasks at once; rather, the mind constantly switches between the tasks and their contexts, spinning one plate at a time.

This is a highly inefficient way of going about things, thanks in part to two different phenomena that arise from task-switching: the psychological refractory period and the attentional blink. Attentional blink, aptly named, is a period of time (around 150 – 500 milliseconds) where the mind completely fails to register any sensory information immediately following a first stimulus. It’s literally as if your mind blinks, where you’re unable to process any visual or auditory information for a half a second after an initial distraction.

The implications of the attentional blink become more significant when viewed in the context of the psychological refractory period (PRP). Due to the brain’s inability to deal simultaneously with two stimuli simultaneously, a person’s decision-making ability and response time suffers significantly for the second stimulus.

In fact, the combination of these two processes in tandem is why you’re not allowed to text and drive at the same time. While 500 milliseconds doesn’t seem like a whole lot of time — at 65mph it translates into 47.7 feet, or roughly three full car lengths (a pretty significant distance when you’re trying to avoid an accident.)

Considering that the tasks of these subjects rank pretty low on attentional demand, you may have even experienced how difficult multi-tasking becomes when dealing with more complicated matters. That’s because activities that require more cognitive control, such as teaching yourself a new subject or skill, light up a region of your brain known as the prefrontal cortex. It’s essential for selective attention, working memory and decision-making. It’s also the area in the front of your brain that coordinates all the rest of the brain to work at a single task at hand.

However, the ability of the prefrontal cortex becomes severely limited when faced with multiple tasks. Every time you switch between two tasks, the PFC must reconstruct an entirely different working memory, signal the rest of the brain system to recreate the necessary context, keep the information between tasks completely separate and compensate for the effects of attentional blink and PRP.

The problem with multitaskers was that their PFC was so occupied with effective task-switching, that it had exhausted much of its abilities when faced with the actual task at hand. Its constant coordination of other brain regions detracted from its abilities in its normal duties.

Brain activity imaging scans showed this to be just the case. Nass discovered through fMRI scans conducted during the task-switching activities that the brains of multitaskers used 20 percent more of their brain, with significantly worse results to show for it.

Their brains sacrificed quality in hopes of quantity and ultimately lost both. When it comes down to it, it’s the quality of practice that’s really the most important factor.

While the prospect of being able to tackle multiple things at once sounds appealing, it’s the fact that we can only attend to one task at a time that makes our abilities all the more special and personal.

It’s what we decide to do with our time, and the focus that we dedicate to it, which makes us as uniquely impressive as the person sitting next to us. Give your time the full attention it deserves, and both your prefrontal cortex and future self will thank you.


A version of this article appeared on page 4 of April 23rd, 2013′s print edition of the Daily Nexus.