Our ability to divide our attention while undertaking various tasks is often lauded as an essential skill in today's rapidly moving world.

We email in meetings, text while driving, and divide our attention among several ongoing tasks. These are moments when we're doing the cognitive equivalent of rubbing our bellies and patting our heads. And we're told that if we're To-Do listers, achieving big things even while crushing a cold in our pyjamas, to go on and bask in our multitasking glory.

If you're good at it (or think you are), you're efficient. But the reverse side of that coin is that, if you're not very good at it (or not even very good at it with significant practice), you're not very efficient.

What we think of as multitasking is really a rapid task switch, this switch having the three characteristics of task switching, as well as two forms of task switching in real-life situations. We may have the impression that we are doing several things at once or that we are doing things simultaneously, but in actuality, we are just really good (mostly) at switching our attention between tasks without losing the thread of what we are doing (too much).

When we walk and talk, we might think we are doing two equally complex things at once, but we're probably doing one with a much higher level of automatic processing than we are applying to the other. And when we rapidly do things one after the other, we might also have the impression that we're multitasking, but in reality, we're just completing tasks in the same time frame we might use to do them if we were doing them in a sequence. These strategies do not embody the kind of parallel processing that occurs when people really do "multitask."

True multitasking is processing two or more modern tasks simultaneously. "Modern" tasks are those that require a relatively high level of cognitive effort. Past tasks, like talking and listening to someone inside a personal conversation, have not measured levels of multitasking well. For real parallel processing, you need a modern task. Our brains, especially the prefrontal cortex responsible for executive functions like attention and working memory, have finite resources to accomplish the high-level demands of modern tasks.

The cognitive toll exacted by multitasking is high. We pay a "switch cost" every time we move our attention from one task to another. This is a small amount of time and mental effort that we use to stop one task and start another. Some researchers argue that we can't pay too much of a price for these switch costs because they're taken in the currency of the precious resource of our arousal and vigilance, the very basis of our sustained attention.

Nevertheless, the costs associated with switching accumulate. As a result, we see reduced efficiency, increased errors, decreased comprehension, and higher stress levels. These are the very things that multitaskers report. Moreover, despite switching tasks, some of our attention remains on the former task a phenomenon termed "attention residue."

This wayward partial focus on the old task disrupts performance on the new task and creates a vicious cycle of inefficiency. It's as if, after changing the significant focus of your cognitive resources, you keep covertly engaging with the old task and must re-priming shift in neural networks to re-engage with the new task.

A variety of studies have found that significant performance drops occur when people switch back and forth between tasks, this is especially true when the tasks being switched between aren't completely different from one another (as example, talking on a cell phone and driving).

Real-world research, including that on the quite relevant topic of driving while talking on a phone, has shown that multitasking leads to poor performance and considerably elevated risks for accidents.

Insufficient time to focus on either one or the other of the two tasks—a nunc-stans, as it were, for the multitasker almost always guarantees that the brain will be performing several different sequential series of "task" operations rather than a few simultaneous ones, a not-so-great scenario for anyone concerned about errors or impaired judgment.

Single-tasking has many benefits that make it appear almost magical in contrast to the illusion of multitasking. When we give our undivided attention to one task, we perform that task more quickly and with greater accuracy.

We process information at a deeper level and understand it better than if we were working with the same amount of information but in a divided state. Our brains appear to be wired for working in a serial fashion, not in a parallel one.

When we embrace the time-honoured practice of working on one thing to completion, we free up not only time for the next task but also cognitive resources for what ought to be the next creative act.

In a society that incessantly inundates us with data and clamours for our focus, the potency of single-tasking has never been more crucial. This is currently the most effective means we have for accessing the seemingly bottomless well of our cognitive potential.

Single-tasking is a deceptively simple strategy that is rendered potent by our obsession with multitasking - an obsession that is largely fuelled by our failure to recognise the number of distractions we create for ourselves. We are built for doing one thing at a time. And that's a good thing.

When we're doing a work project or something more personal, we're using the brain circuit dedicated to that specific task. And doing so is the most effective way to work. Whether what we're doing is a problem on the job or a matter of personal importance, we have the great (and perhaps underutilised) potential to tap into the brain circuit dedicated to that task.