Archive for Wednesday, September 5, 2001

Multitasking a waste of time

September 5, 2001


Children watch TV while they do their homework. Executives talk to employees while they write e-mail. Drivers dial cell phones while they careen down interstates. Mothers stir the beans and chat with friends while they nuzzle toddlers perched on their hips.

It's the American way of life: Never ever do one thing when you could do two or three.

It may be the ultimate expression of American hip: Buy a latte while skimming a newspaper and talking loudly, way too loudly, into your chic black headset.

It's a waste of time.

That's right. Doing more than one task at a time doesn't save time; it wastes time.

And harms competency.

Today's brain researchers can actually watch the brain at work by measuring blood and oxygen flow. They can watch us attempt the simple or complex, do one task, do two at once or switch from one task to another. They can see just what kind of effort we're making and where in the brain that effort takes place.

And what they've got to say is: We're fooling ourselves.

Perform two demanding tasks at once, and you do neither as well as if you had focused one by one. And you take longer.

Researchers at Carnegie Mellon's Center for Cognitive Brain Imaging used functional magnetic resonance imaging (fMRI) to detect the "hot" or active spots in the brain, measured in "voxels." Voxels are tiny portions, one-twentieth of a cubic centimeter.

The Pittsburgh researchers scanned volunteers' brains as they listened to complex sentences and/or tried to mentally rotate, then match, three-dimensional objects.

The volunteers' brains used 37 voxels in the temporal regions to work with language. Their brains also required 37 voxels, in the parietal regions, to do the mental rotation task. But no one doubled their pleasure, their fun or their voxels doing both tasks at once.

So much for feeling like Mr. or Ms. Efficient.

When volunteers listened to sentences and then tried the mental-rotation task, brain activation in the temporal regions decreased 53 percent. When volunteers mentally rotated objects and then tried to listen to sentences, brain activation decreased 29 percent in the parietal regions.

We know what this is called: Robbing Peter to pay Paul.

"It's really surprising how much the brain activation goes down when trying to do two things simultaneously," Marcel Just, leader of the CMU research team, told the Pittsburgh Post-Gazette.

So, you decide you can multi-task by focusing for a bit then switching, a few minutes here, a few minutes there? Won't help.

Switching back and forth among tasks harms efficiency and takes time, according to another recent study.

Researchers at the University of Michigan asked students to perform a series of tasks, such as identifying geometric shapes or solving math problems, and to switch back and forth between the tasks.

Some of the tasks were familiar, some unfamiliar; some applied simple rules, some complex. Time costs increased when people switched from familiar to unfamiliar tasks or switched back and forth between complex tasks.

When doing mental arithmetic, for example, volunteers were quicker doing batches of multiplication or division problems together, rather than alternating between multiplication and division.

Not only each task, but the switching, too, requires mental processes. The switching itself takes time, fractions of a second, but fractions that add up. In some situations, multi-tasking increased the time needed by 50 percent. And quality suffered.

"Not only speed of performance, the accuracy of the performance, but what I call the fluency of performance, the gracefulness of the performance, was negatively influenced by an overload of multi-tasking," David E. Meyer, a co-author of the multi-tasking study, told The Hartford Courant.

"Thus, multi-tasking may seem more efficient on the surface, but may actually take more time in the end," warns an American Psychological Assn. summary of the study.

Both research teams point out that such studies of the brain doing work are important in a culture that promotes technological overload and advocates juggling many things at once. So the research deliberately mirrors real-life situations, experienced by pilots, 911 operators, air-traffic controllers and, yes, drivers on cell phones. The Federal Aviation Administration, the Navy and the Air Force Office of Scientific Research were involved in funding.

It seems we can do the simple and familiar together: ride a stationery cycle while reading, ponder the grocery list while mopping, talk while preparing a favorite recipe.

But the brain has its limits. Both Just and Meyer noted in interviews that the brain is a biological entity; it can do only so much at one time.

Obviously, they haven't looked at a brain on motherhood. If mothers didn't do six things at once not two, six the world (or at least families) might come to an end. And dinner surely wouldn't be served on time.

But then the sleep-deprived, stressed-to-the max jugglers would also be the first to admit they're doing a lot, but doing less well. That their speech has devolved to baby talk, that a night on the town has lost its appeal while sleep has gained an inestimable allure, that a cold or the flu or burnout or depression lurk just around the corner.

There's something comforting, then, in being told that the 24/7 culture is not only taxing, it's inefficient. It's a delusion.

So go ahead, find a quiet place and focus. Focus on just one thing at a time, and do it well. You, and the world, will be better for it.

Claudia Smith Brinson is a columnist for The State in Columbia, S.C. Her e-mail address is

Commenting has been disabled for this item.