Those Facebook clicks, email checks and instant messages seem tiny and insignificant, but research has shown that excessive task-switching throughout the workday can rack up as much as a 40 percent loss in productivity [source: Weinschenk]! Such performance failure can quickly cost a company big bucks, not to mention throw an employee's job stability into question.
Productivity loss and potential unemployment aren't the only detrimental side effects to multitasking, however. Multitasking and its step-brother, interruptions, are known to impact safety, particularly in high-risk fields/experiences like aviation, healthcare and driving. The latter, in particular, is frighteningly common, with about 660,000 drivers in the U.S. at any daylight moment using cellphones or other electronic devices while behind the wheel [source: Distraction.gov].
IQ scores also take a hit when people are multitasking, according to a University of London study, in which some male participants experienced an IQ dip of 15 points while multitasking during cognitive skills tests. That's equivalent to staying up all night, or the IQ of a typical 8-year-old kid! Women fared better, however, with "only" a five point drop in IQ [source: Stillman].
Given the IQ decline, it's not shocking that people are also more prone to make mistakes when multitasking. A 2010 French study found that participants were able to adequately handle two tasks at a given time, but a third caused significant errors — three times as many errors as when they were handling just two tasks. The researchers noted that the brain's two hemispheres appear equipped enough to handle two tasks, but a third task put the brain into overload. However, a lot depended on the difficulty of the tasks. Walking, chewing gum and checking your smartphone is easier than driving, eating some fries and looking at your smartphone.
Physiologically speaking, multitasking isn't doing you any favors, either. A University of California, Irvine study showed that frequent interruptions cause people to work faster to compensate for lost time, resulting in elevated stress levels and pressure. Socially, failure to devote attention to important personal conversations and relationships can also cause major issues.
"Buying into the myth of multitasking allows us to convince ourselves that we can do it all and that we don't have to make hard decisions about where to spend our time. The more you fall into the trap of multitasking the less you commit to one clear priority," author Clear explains. "I think this ends up costing us in a very big way over the long term because the people who rise to the top of nearly every field are the ones who show some sort of unwavering commitment to that area (often combined with natural talent)."