The brain cannot multitask. Multitasking, when it comes to paying attention, is a myth. The brain naturally focuses on concepts sequentially, one at a time…To put it bluntly, research shows that we can’t multitask. We are biologically incapable of processing information-rich inputs simultaneously…Studies show that a person who is interrupted takes 50 percent longer to accomplish a task. Not only that, he or she makes up to 50 percent more errors. John Medina

In developmental molecular biologist John Medina‘s book Brain Rules: 12 Principles For Surviving and Thriving at Work, Home, and School (2008), he talks about the myth of multitasking. It’s, in fact, something we’re “biologically incapable” of doing.

The following advice is taken directly from his blog: “The brain is a sequential processor, unable to pay attention to two things at the same time. Businesses and schools praise multitasking, but research clearly shows that it reduces productivity and increases mistakes. Try creating an interruption-free zone during the day—turn off your e-mail, phone, IM program, or BlackBerry—and see whether you get more done.”

By the way, Medina’s 12 “brain rules” for “surviving and thriving at work, home, and school” are listed below in the order he gives them in the book:

1. Exercise boosts brain power.
2. The human brain evolved too.
3. Every brain is wired differently.
4. We don’t pay attention to boring things.
5. Repeat to remember.
6. Remember to repeat.
7. Sleep well, think well.
8. Stressed brains don’t learn the same way.
9. Stimulate more of the senses.
10. Vision trumps all other senses.
11. Male and female brains are different.
12. We are powerful and natural explorers.

Guess which of the 12 rules Medina thinks “are most important to the average person?” Medina readily will say they’re exercise, stress, and sleep.

And, of those three, which two particularly affect our emotional well-being (more than the excluded one)? Exercise and stress. Although lost sleep also does a number on us, Medina places more emphasis on its possible effects on learning.