Multitasking is a mantra in our 24/7 world. We grudgingly admire the efficiency of people who greet us at the grocery store while talking on their cell phones as they shop for dinner and check their messages. But there is good news for those of us who find it tough to do more than one thing at a time. Multitasking is largely a myth. In fact, researchers have figured out that people who multitask the most are generally the worst at it.

"People who multitask the most tend to be impulsive and easily distractible," researcher David Sanbonmatsu, told TheDoctor. "Our data show that people multitask because they have difficulty focusing on one task at a time. They get drawn into secondary tasks."

Any task requires a certain amount of attention. It's often more efficient to focus on doing one thing at a time, rather than spend extra energy switching attention from task to task.

Study participants were tested on how much they multitasked, how good they thought they were at multitasking, and on measure of impulsivity, and sensation seeking. Researchers also measured their ability to focus and control their attention and actual multitasking ability.

People who were most likely to multitask tended to delude themselves, believing they were better at it than others, when the results showed they are no better and often worse. People who scored highest on the multitasking ability test were the least likely to use multiple forms of media, such as a cell phone or computer, simultaneously, and were also the least likely to talk on their cell phone while driving. Those who use a cell phone while driving need the stimulation of talking while driving because they are bored — their attention has wandered. They are probably among the worst multitaskers. This finding makes a strong case for legislation prohibiting driving and cell phone use, according to the study's authors, all at the University of Utah.

Ironically, the best multitaskers are those who are least likely to multitask. They know they can get more done faster by paying attention to one thing at a time. In reality, multitasking is about shifting one's attention quickly between tasks, a demanding mental exercise in itself. Any task requires a certain amount of attention. It's often more efficient to focus on doing one thing at a time, rather than spend extra energy switching attention from task to task.

So the next time you are tempted to call a friend while driving home or checking your email as you engage in a business call, consider this: using more than one form of media at a time was associated with impulsivity, particularly the inability to concentrate and acting without thinking, according to Sanbonmatsu. He goes on to say that those who are impulsive are often more reward-oriented and bigger risk takers, which makes them more likely to multitask, even if it is a less efficient way to get things done, and more likely to make a mistake. So probably the most efficient and quickest way to burn through a long to-do list is to focus on one thing at a time.

The study is published in the journal, PLOS One and freely available.