When they “multitask,” they switch back and forth, alternating their attention until both tasks are done.

People can actually do two or more things at once, such as walk and talk, or chew gum and read a map; but, like computers, what we can’t do is focus on two things at once.

• There is just so much brain capability at any one time. Divide it up as much as you want, but you’ll pay a price in time and effectiveness.
• Bounce between one activity and another and you lose time as your brain reorients to the new task. Those miliseconds add up. Researchers estimate we lose 28 percent of an average workday to multitasking ineffectiveness.

-The One Thing, p.44