Why is it difficult to multi-task?20th April 2010
The human brain can only handle about two simultaneous tasks, according to a recent French study.
The study suggests that people should not try to juggle more than two things at the same time.
The reason why the limit seems to be set at two simultaneous tasks has to do with how the brain delegates its processing power.
Etienne Koechlin of the Université Pierre et Marie Curie in Paris, France said that the finding showed people were very much able to multi-task.
He said that people could easily talk on the phone and cook at the same time, although they could not effectively do more than two things at once.
When people multi-task, the medial prefrontal cortex (MPC), which is located in the front of the brain, divides itself in half.
Half of the MPC, which is thought to be part of a neurological system that evaluates rewards, focuses on the first task, and half on the second.
Previous studies have shown that the anterior prefrontal cortex is also used when people multi-task.
For the study, the researchers assigned a letter-matching task to 32 study subjects, half of whom were either male or female, and all of whom were between the ages of 19 and 32.
The subjects were asked to evaluate the spelling of certain words, some of which had letters in the wrong order.
If the study subjects were able to correctly match the letters to spell different words without any errors, they were rewarded with money.
In order to evaluate the effect the reward would have upon brain processing, the researchers gradually increased the amount of money on offer.
As the amount of money increased, MFC activation also increased.
Then the researchers split the task into two simultaneous parts by showing the subjects upper case and lower case letters at the same time.
The subjects had to evaluate both the ordering of the upper case letters and the lower case letters.
Koechlin said that, when his team started getting the subjects to multi-task, their brains split into two halves, and each half behaved as if it were pursuing its own goal.
He said that when the third task was introduced, the subjects systematically forgot one of the three tasks.
The third task caused the subjects' accuracy to drop, because it was consistently refused by both hemispheres.
Mark Mapstone, an assistant professor of cognitive behavioural neurology at the University of Rochester in New York, said that the task the researchers set the subjects had been fairly demanding.
He said that the findings suggested that people could not handle too many things at the same time, and that it was not a good idea to drive while talking on the phone.
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Title: Why is it difficult to multi-task?
Author: Luisetta Mudie
Article Id: 14650
Date Added: 20th Apr 2010