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Double Trouble: The hidden costs of multitasking

POSTED AT 12:00 AM ON Aug. 28, 2007 


Concentrating on two or more tasks at once seems like a staple of collegiate life. Many students have made a habit of talking on the phone while driving, reading the newspaper while walking to classes and listening to music or chatting online while studying.

“Multitasking is my life,” said junior Katie Atkins.

But, when it comes to getting ready for exams or writing research papers – tasks that require a lot of concentration – a majority of people will focus on one task at a time.

Why do humans do that? Are parents right about the inefficiency and dangers of multitasking?

Sharlene Newman, an assistant professor of psychology at IU, has studied brain activity during dual-task performance to answer questions on multitasking. In her study, Newman, together with her colleagues at Carnegie Mellon University in Pittsburgh, has found that people can’t equally perform visual/spatial and auditory language tasks simultaneously, especially when one or both tasks are complex and demand a lot of attention.

“People should be aware that there are limitations to dual tasking, that we really can’t do multiple things simultaneously as well as we could do them alone,” Newman said.

In the study sponsored by Carnegie Mellon, Newman and other scientists used functional MRI to look at brain activity in 15 participants, including four women, who were all students between ages 18 to 26 at the university. Scientists examined participants’ responses to complex visual and auditory tasks, the latter involving answering true or false to statements on general knowledge. Participants performed both tasks alone and together.

By observing changes in oxygen concentration in blood, Newman and her colleagues were able to tell which part of the participant’s brain was activated while responding to each task.

“Any time a part of the brain becomes active, it requires more oxygen,” Newman said.

More brain activity means more mental resources, including attention, spent to complete the task, she said.

The scientists found that the part of the brain responsible for the visual/spatial tasks was more activated when participants performed mental Tetris-like rotations of 3-D cubical figures only, than while attempting to perform dual tasks. The same was true about the part of the brain responsible for the auditory language task.

By using neuroimaging, a relatively new approach in studying multitasking, Newman concentrated specifically on selective attention or, as she said, “how well (one) can ignore language stimuli or not let its presence affect one’s performance on another task.”

Divided attention during simultaneous-task performance results in a poor performance in both, but Newman found that language comprehension, in particular, suffers significantly during dual-task performance and that it interferes with other tasks. Talking on the phone while driving is an example.

While Newman’s study supports the findings of other studies on multitasking, it also contradicts some. For example, she didn’t find that the prefrontal cortex, a part of the brain responsible for allocating attention, helps to control task switching during dual task performance, thus indicating the human brain’s limited ability to multitask. In a different study using neuroimaging, Jean-Claude Dreher and Jordan Grafman of the National Institutes of Health found that the prefrontal cortex helps to resolve the conflict in stimulus response during dual-task performance.

Newman’s study, published in the academic journal Human Brain Mapping in 2007, throws further light on the mechanisms behind multitasking. She said, however, that further studies observing dual-task performance in the real world versus the lab would provide more explanation of the extent and limits of humans’ ability to multitask and the implications of multitasking.

Meanwhile, Newman warns that while “it’s always a good thing to multitask, it’s (important) to pick situations that won’t be dangerous to anyone.”

Can people develop a multitasking skill, though?

“Some people can after training,” Newman said.

How can humans train themselves to do two tasks at the same time without sacrificing the quality of work and its product? Answering this question is Newman’s next step.

In the meantime, a majority of scientists advise giving 100 percent to a single task. Studying for the exam may not be a bad idea after all – for students that want to get an A.


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