Curb multitasking, reap efficiency, studies find

Technology can help speed work, but too much can become disruptive

March 25, 2007|By New York Times News Service

Confident multitaskers of the world, your attention please.

Think you can juggle phone calls, e-mail, instant messages and computer work to get more done in a time-starved world? Read on, preferably shutting out the cacophony of digital devices for a while.

Several research reports, both recently published and not yet published, provide evidence of the limits of multitasking. The findings, according to neuroscientists, psychologists and management professors, suggest that many people would be wise to curb their multitasking behavior when working in an office, studying or driving a car.

These experts have some basic advice. Check e-mail messages once an hour, at most. Listening to soothing background music while studying may improve concentration. But other distractions - most songs with lyrics, instant messaging, television shows - hamper performance. Driving while talking on a cell phone, even with a hands-free headset, is a bad idea.

In short, the answer seems to lie in managing the technology, instead of merely yielding to its incessant tug.

"Multitasking is going to slow you down, increasing the chances of mistakes," said David E. Mayer, a cognitive scientist and director of the Brain, Cognition and Action Laboratory at the University of Michigan. "Disruptions and interruptions are a bad deal from the standpoint of our ability to process information."

The human brain, with its hundred billion neurons and hundreds of trillions of synaptic connections, is a cognitive powerhouse in many ways. "But a core limitation is an inability to concentrate on two things at once," said Rene Marois, a neuroscientist and director of the Human Information Processing Laboratory at Vanderbilt University.

Marois and three other Vanderbilt researchers reported in an article last December in the journal Neuron that they had used magnetic resonance imaging to isolate the processing bottleneck in the brain and to measure the efficiency loss of trying to handle two tasks at once.

The tasks involved responding to sounds and images. The first was to press the correct key on a computer keyboard in response to hearing one of eight sounds. The other task was to utter the correct sound in response to seeing one of eight images.

The researchers found that responses were delayed by up to a second when the study participants were given the two tasks at the same time.

In many daily tasks, of course, a lost second is unimportant. But one implication of the Vanderbilt research, Marois said, is that talking on a cell phone while driving a car is dangerous. A one-second delay in response time at 60 mph could be fatal, he pointed out.

"We are under the impression that we have this brain that can do more than it often can," observed Marois, who said he turns off his cell phone when driving.

The young, according to conventional wisdom, are the most adept multitaskers. Just look at teenagers and workers in their 20s, e-mailing, instant messaging and listening to iPods at once.

Recently completed research at the Institute for the Future of the Mind at Oxford University suggests that the popular perception is open to question. A group of 18- to 21-year-olds and a group of 35- to 39-year-olds were given 90 seconds to translate images into numbers, using a simple code.

The younger group did 10 percent better when not interrupted. But when both groups were interrupted by a phone call, a cell phone text message or an instant message, the older group matched the younger group in speed and accuracy.

"The older people think more slowly, but they have a faster fluid intelligence, so they are better able to block out interruptions and choose what to focus on," said Martin Westwell, deputy director of the institute.

Westwell is 36, and should theoretically be better able to cope with interruptions. But he has modified his work habits since completing the research project last month.

"I check my e-mail much less often," he said. "The interruptions really can throw you off-track."

In a recent study, a group of Microsoft workers took, on average, 15 minutes to return to serious mental tasks, like writing reports or computer code, after responding to incoming e-mail or instant messages. They strayed off to reply to other messages or browse news, sports or entertainment Web sites.

"I was surprised by how easily people were distracted and how long it took them to get back to the task," said Eric Horvitz, a Microsoft research scientist and co-author, with Shamsi Iqbal of the University of Illinois, of a paper on the study that will be presented next month.

"If it's this bad at Microsoft," Horvitz added, "it has to be bad at other companies, too."

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