Task-Juggling Can Be Dangerous Balancing Act

Safety concerns can override benefits of efficiency, researchers say

MONDAY, Sept. 3, 2001 (HealthDayNews) -- An air traffic controller monitors several flights at once while pouring sugar in his coffee and answering a phone. A soccer mom drives kids to a game while making dinner reservations on her cell phone. To most of us, multi-tasking is a way of life that seems expedient and efficient.

But researchers have concluded that such juggling is sometimes not as efficient as we may think, and can quite often be downright dangerous.

Researchers with the Federal Aviation Administration and the University of Michigan were interested in how the brain manages to handle various tasks at once.

The part of the brain that coordinates such tasks is called the executive control. To find out its abilities and limitations, the researchers decided to see if there were patterns in the amount of time lost when people switched repeatedly between two tasks of varying complexity and familiarity.

In four experiments, groups of up to 24 young adults were asked to switch between different tasks, such as solving math problems or classifying geometric objects.

Meanwhile, the researchers measured the speed of their performance in relation to the familiarity and ease of the task.

The results showed that time was indeed lost when a person switched from one task to another. Perhaps not surprisingly, even more time was lost if the new task was more complex or unfamiliar.

"When you have to switch from a routine task to a non-routine one, the time cost can be, relatively speaking, especially large," says David Meyer, a professor of psychology at the University of Michigan and co-author of the study. "However, even with routine tasks, in some conditions there will be substantial costs from multi-tasking."

The study is published in the current issue of the Journal of Experimental Psychology: Human Perception and Performance.

So what, specifically, is going on in there when we multi-task? The researchers explain that as we move from one task to another, our "executive controls" undergo a two-stage process. The first stage is goal shifting, ("I want to do this now instead of that") and the second stage is rule activation ("I'm turning off the rules for that and turning on the rules for this").

Though seemingly instantaneous, each activation of the process actually eats up several tenths of a second and those instants can add up quickly as people switch back and forth repeatedly.

And in situations that involve driving, those instants can add up to the kind of momentary distraction that can have disastrous results, says Meyer.

"When you're driving, for instance, you're using your inner ear and your inner voice. Meanwhile, when you're having a cell phone conversation, you also need to be using your inner ear and voice. And since you only have one set of ears and one voice, they either get devoted to the cell phone conversation or the driving," Meyer says.

"And if you've decided to devote them to your cell phone conversation and something unexpected or dangerous comes up, you could easily crash."

On the professional level, the findings may help pave the way for more training or solving of similar problems that can occur in any number of workplace environments, particularly in air traffic control or other similar activities in which people must monitor and manipulate the environment through technologically advanced devices.

But Merrill Hiscock, a University of Houston professor of psychology, explains that even with extensive conditioning, that executive control has its limits.

"Most theories in cognitive psychology assume that there's either a finite level of capacity or attention that we can allocate in different ways," Hiscock says.

"We can divide that capacity between two or three activities, but only at the expense of depriving each of those activities the full compliment of our attention."

While the alternative to multi-tasking -- reducing assignments to just a few familiar and easy tasks -- may seem fraught with its own drawbacks of monotony and boredom, Meyer says there can indeed be a happy medium.

"What needs to be done is to develop appropriate criteria plans of time management so as to avoid as much as possible the time costs that are involved with multi-tasking, while at the same time not creating the monotony of an assembly line."

"This is possible -- I think you can have your cake and eat it too, with appropriate sophisticated time management rules. The trick is to avoid multi-tasking by allotting yourself significant chunks of time and when you get tired of that and start to suffer from mental fatigue, then it's time to take a break, refresh yourself, and then come back to perform some other task," Meyer explains.

What To Do

Visit the Association for Worksite Health Promotion for more information on managing the kinds of workplace stresses that can result from multi-tasking.

If you think the stress from juggling a few too many tasks is getting to you, read this article from the American Psychological Association on Stress: How and When To Get Help.

SOURCES: Interviews with David Meyer, Ph.D., professor of psychology, University of Michigan, Ann Arbor; Merrill Hiscock, Ph.D., professor of psychology, University of Houston, Texas; August 2001 Journal of Experimental Psychology: Human Perception and Performance.
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