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Research / Discovery

Drunk on too many tasks

October 1, 2010
By Nik Olsen

Multitasking is associated with the myth - yes, it's a myth - that people can effectively perform different tasks at the same time. Given all the technological devices for on-the-go communication, information gathering, and entertainment, multitasking typically is touted as a way to maximize work-load efficiency.

Our brains can only execute one task at a time

Ben Clegg and his students are studying how the brain deals with the cognitive cost of trying to do too much at once.

Researchers have found that our brains can only execute one task at a time. Each time you switch your attention, it comes at a cost – no matter how adept someone thinks they are at multitasking, the brain must recalibrate to the new task. To bolster research into our crowded minds, Ben Clegg, associate professor of cognitive psychology at Colorado State University’s College of Natural Sciences, and his student researchers are studying how the brain deals with its workload and the cognitive costs of trying to do too much at once.

“Situational awareness is not just what you know, but what you can project will happen,” he says. To explore how much the brain can handle during multiple tasks, Clegg uses the act of driving, one of the most frequent and mentally taxing tasks humans can undertake. While research subjects are driving, Clegg and his team introduces “X” factors, such as counting backward by three or tapping a cell phone to simulate texting.

Car simulator with motion platform

Not to worry: Intentionally distracting a driver of a car that’s on the street is far too dangerous, so the team uses an automotive simulator in the basement of CSU’s newest classroom building, the Behavioral Sciences Building. The simulator – which can send a virtual child dashing into the road or a driver blowing through a stop sign – has been moved to this gleaming new facility and upgraded with a motion platform that adds even more realism.
Participants in a study conducted by graduate student Lisa Blaylock where asked to take a spin around the virtual environment. While doing so, they were asked to count backwards by threes to simulate the mental load of a phone conversation.

Blaylock’s results found that dynamic objects – anything that’s in play around you, such as other vehicles and pedestrians – are the first thing a person loses track of while their brain switches from driving to talking. Things that don’t even move, like signs and other landmarks, are recalled much more readily.

Potentially life-saving research

It’s potentially life-saving research. Fatalities caused by distracted driving have increased 28 percent since 2005 and texting while driving resulted in more than 16,000 additional distracted driving fatalities from 2002 to 2007, according to the American Journal of Public Health.

Another of Clegg’s students, undergraduate Ben Sawyer, conducted a study using the simulator that asked participants to hold a cell phone and tap while driving. Sawyer found that simply tapping a phone was easy, but once the subject was asked to type out text, their driving awareness nosedived.

Texting while driving = 23 times as likely to crash

There's no data that says hands-free phones are any better than a handheld phone.

Using a cell phone while driving makes you four times as likely to be involved in a crash, Clegg says, but texting while driving makes you 23 times as likely to be involved in a car crash.

So do hands-free phones reduce the mental load on your brain? “There’s no data that says hands-free phones are any better than a handheld phone,” Clegg says, noting that the difficulty comes when switching tasks in the brain between thinking about driving and constructing sentences for a conversation, not the easier motor requirements for holding a phone.

Multitasking is an illusion

Multitasking, then, is an illusion, Clegg says. A student studying in a distracting environment – perhaps with the television on – may say they’re studying harder than they would in silence. But it’s the mental effort of switching attention from TV to studying and back that causes the mental fatigue the student may notice.

Clegg notes one last example. It takes the human brain about 200 milliseconds to switch tasks, and at 30 mph, a car can travel 6 or 7 feet in that amount of time.

“If you were the pedestrian,” he says, “you’d want a car to stop 6 or 7 feet in front of you rather than after.”