You may have heard that multitasking is bad for you, but studies show that it kills your performance and may even damage your brain. Every time you multitask you aren't just harming your performance in the moment; you may very well be damaging an area of your brain that's critical to your future success at work.

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Research conducted at Stanford University found that multitasking is less productive than doing a single thing at a time. The researchers found that people who are regularly bombarded with several streams of electronic information cannot pay attention, recall information, or switch from one job to another as well as those who complete one task at a time.

A Special Skill?

But what if some people have a special gift for multitasking? The Stanford researchers compared groups of people based on their tendency to multitask and their belief that it helps their performance. They found that heavy multitaskers — those who multitask a lot and feel that it boosts their performance — were actually worse at multitasking than those who like to do a single thing at a time. The frequent multitaskers performed worse because they had more trouble organizing their thoughts and filtering out irrelevant information, and they were slower at switching from one task to another.

Ouch.

Multitasking reduces your efficiency and performance because your brain can only focus on one thing at a time. When you try to do two things at once, your brain lacks the capacity to perform both tasks successfully.

Multitasking Lowers IQ

Research also shows that, in addition to slowing you down, multitasking lowers your IQ. A study at the University of London found that participants who multitasked during cognitive tasks experienced IQ score declines that were similar to what they'd expect if they had smoked marijuana or stayed up all night. IQ drops of 15 points for multitasking men lowered their scores to the average range of an 8-year-old child.

So the next time you're writing your boss an email during a meeting, remember that your cognitive capacity is being diminished to the point that you might as well let an 8-year-old write it for you.