Why Multitasking Isn’t Efficient

Multitasking is a myth: Your brain is actually rapidly switching focus from one task to another.

Medically Reviewed by Patricia A. Farrell, PhD on August 21, 2008

Kris Oser, 37, of Hastings-on-Hudson, N.Y., is an email fiend. A single mother and director of communications for a market research company, she has to be immediately accessible to executives and the news media.

That means Oser is often on the phone and messaging several people at the same time -- and that can lead to trouble. In one recent gaffe, she mistakenly emailed a reporter at The Wall Street Journal instead of her best friend, asking her to pick up Oser’s daughter from school.

“Speed is the modern, natural high,” says psychiatrist Edward Hallowell, MD, director of the Hallowell Center for Cognitive and Emotional Health in Sudbury, Mass. But he insists that true multitasking is a myth. We may feel we’re doing two -- or more -- things at once, but it’s an illusion. Instead, we’re quickly switching our focus back and forth.

That’s because the cerebral cortex can pay attention to only one thing at a time, says Hallowell. “What people really do is shift their attention from one task to the next in rapid succession. That reduces the quality of the work on any one task, because you’re ignoring it for milliseconds at a time.”

The cortex handles “executive control” -- that is, allocating the mind’s resources and prioritizing between tasks. However, there’s a lag of up to several tenths of a second each time it handles a switch, according to a University of Michigan study completed for the Federal Aviation Administration. This tiny bit of time can add up to big inefficiencies, the study shows.

Distraction can also be dangerous. David Strayer, a professor of psychology at the University of Utah in Salt Lake City and an expert on driver distraction, has found that a motorist talking on a cell phone is every bit as impaired as someone who’s legally drunk. And there are health costs: Stress, including the self-imposed kind, means more cortisol into the bloodstream. Chronically elevated levels of cortisol can damage the heart, cause high blood pressure, suppress the immune system, and make you susceptible to type 2 diabetes.

Even so, Oser says you couldn’t pry her away from her BlackBerry. But she does constantly try to remind herself, “The human brain must be honored for the way it actually operates.”

Ready to be here, now? Hallowell offers these four strategies for managing your crazy-busy life:

  • Mix and match. Pair high-cortical involvement tasks -- those that involve judgment -- with routine, physical tasks that the cerebellum, the brain’s autopilot, can handle. For example, talk to your mom on the phone while folding laundry.
  • Rest your case. If your hectic schedule demands you rise at the crack of dawn, steal an hour from the TV at night. A sleepy brain can’t focus.
  • Wean from screens. Resist email, the Internet, texting -- anything that’s not essential to the work you’re doing right now.
  • Ban boredom. Try to do what you love and what matters most. Organize your life around this principle, and you won’t be tempted away from the task at hand.

Show Sources


Edward M. Hallowell, MD, director, Hallowell Center for Cognitive and Emotional Health, Sudbury, Mass.

Galinsky, E. et al., “Overwork in America: When the way we work becomes too much” Families and Work Institute, 2005.

Strayer, D. and Drews, F. Current Directions in Psychological Science, 2007; vol 16: pp 128-131.

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