Stanford study shows that heavy multitasking degrades attention, memory and more; recent study suggests the possibility that training can reduce these performance deficits
by Craig Weatherby
Based on the results of a simulation by researchers at Stanford University, switching repeatedly among several streams of electronic information incurs mental performance costs.
Overall, people who multitask perform poorly compared with those who tend to complete one task at a time.
As a press release from Stanford says, “Attention, multitaskers (if you can pay attention, that is): Your brain may be in trouble” (Gorlick A 2009).
The goal of the study was to seek any mental advantages or deficits, if any, among students who keep up multiple e-mail and instant message conversations at once, text message while watching television, and jump from one website to another while plowing through homework assignments.
|Can you train for multitasking?|
Last month, researchers at Vanderbilt University published the results of a less-noticed study, which suggest that practice may make multitasking, if not a perfect choice, one that’s less likely to impact work efficiency and quality (Dux PE et al. 2009).
They found that extensive training can greatly reduce the deterioration in task performance seen when people attempt to undertake two or more tasks simultaneously.
The task included responses to two auditory stimuli that each required a distinct vocal response; trials where subjects were presented with one of two faces that each required a distinct speeded finger-press response; and trials where subjects were presented with both the visual and auditory tasks simultaneously.
Training on these tasks took place over several sessions during a two-week period, and it reduced the reaction times to each task under both single- and dual-task conditions.
However, as they wrote, there are still costs associated with multitasking: “…training was successful in reducing multitasking costs to approximately one tenth of their initial value, although it did not eliminate such costs altogether as the residual multitasking costs were still significant… as has been found in previous behavioral studies” (Dux PE et al. 2009)
And we’re dubious that the results of training people on two very simple, repetitive tasks can be applied the real world, where one cannot really train for the myriad of dissimilar tasks we tend to engage in.
Other than gaining increasing familiarity with the various software and hardware used most often in office work, it is hard to see how can you can train the brain in advance to deal faster with an ever-changing set of tasks and interruptions to which one pays attention intermittently.
While it is not known how training alters the brain to solve the simple multitasking problem tested in this study, it likely involves the prefrontal cortex given this brain region's purported role in limiting multitasking performance.
The Vanderbilt seems to show that the reduction in performance deterioration is achieved by increasing the speed of information processing in the prefrontal cortex of the brain, thereby allowing multiple tasks to be processed in rapid succession.
These results seem to reveal how training leads to efficient multitasking, and link the deficits seen with multitasking on reduced speed of information processing in the prefrontal cortex.
But to some extent, the results should apply to anyone engaging in similarly frenetic multitasking at work.
After putting about 100 students through a series of three tests, the researchers concluded that heavy media multitaskers are paying a big mental price (Ophir E et al. 2009).
“They're suckers for irrelevancy,” said communication Professor Clifford Nass, one of the researchers whose findings are published in the August 24 edition of Proceedings of the National Academy of Sciences. “Everything distracts them” (Gorlick A 2009).
Social scientists have long assumed that it's impossible to process more than one string of information at a time. The brain just can't do it.
So many researchers have assumed that people who appear to multitask must have superior control over what they think about and what they pay attention to.
So Nass and colleagues Eyal Ophir and Anthony Wagner set out to learn what gives multitaskers their alleged edge … and test whether an edge even exists.
Alleged edge doesn’t pan out
“We kept looking for what they’re better at, and we didn't find it,” said Ophir, the study's lead author and a researcher in Stanford's Communication Between Humans and Interactive Media Lab (Gorlick A 2009).
The researchers split their subjects into two groups: those who regularly do a lot of media multitasking and those who don't.
In one experiment, the groups were shown sets of two red rectangles alone or surrounded by two, four or six blue rectangles. Each configuration was flashed twice, and the participants had to determine whether the two red rectangles in the second frame were in a different position than in the first frame.
They were told to ignore the blue rectangles, and the low multitaskers had no problem doing that. But the high multitaskers were constantly distracted by the irrelevant blue images. Their performance was horrible.
Because the high multitaskers showed they couldn't ignore things, the researchers figured they were better at storing and organizing information. Maybe they had better memories.
The second test proved that theory wrong. After being shown sequences of alphabetical letters, the high multitaskers did a lousy job at remembering when a letter was making a repeat appearance.
“The low multitaskers did great,” Ophir said. “The high multitaskers were doing worse and worse the further they went along because they kept seeing more letters and had difficulty keeping them sorted in their brains.”
Still puzzled, they pressed on
Puzzled but not yet stumped on why the heavy multitaskers weren't performing well, the researchers conducted a third test.
If the heavy multitaskers couldn't filter out irrelevant information or organize their memories, perhaps they excelled at switching from one thing to another faster and better than anyone else.
Wrong again, the study found.
The test subjects were shown images of letters and numbers at the same time and instructed what to focus on. When they were told to pay attention to numbers, they had to determine if the digits were even or odd. When told to concentrate on letters, they had to say whether they were vowels or consonants.
Again, the heavy multitaskers underperformed the light multitaskers.
“They couldn't help thinking about the task they weren't doing," Ophir said. "The high multitaskers are always drawing from all the information in front of them. They can't keep things separate in their minds” (Gorlick A 2009).
The researchers are still studying whether chronic media multitaskers are born with an inability to concentrate or are damaging their cognitive control by willingly taking in so much at once. But they're convinced the minds of multitaskers are not working as well as they could.
“When they're in situations where there are multiple sources of information coming from the external world or emerging out of memory, they're not able to filter out what's not relevant to their current goal,” said Wagner, an associate professor of psychology. “That failure to filter means they're slowed down by that irrelevant information” (Gorlick A 2009).
Michigan group makes similar findings
Scientists at the University of Michigan Brain, Cognition and Action Laboratory have studied this subject in depth.
We recommend their website which includes links to their studies, and this cogent summary by Principal Investigators David Meyer, Ph.D. and David Kieras, Ph.D.:
“Multitasking can be difficult when a person must perform two tasks simultaneously, but problems can also occur when a person switches from performing one task to performing another. Performing two or more tasks in rapid succession requires an individual to reorient to each new task, which itself takes time and other attentional resources.”
So maybe it's time to stop e-mailing while you’re also writing a report, watching YouTube, and tallying sums in a spreadsheet.
By doing less at once, you might accomplish more, better work in less time!
- Dux PE, Tombu MN, Harrison S, Rogers BP, Tong F, Marois R. Training improves multitasking performance by increasing the speed of information processing in human prefrontal cortex. Neuron. 2009 Jul 16;63(1):127-38.
- Gorlick A. Media multitaskers pay mental price, Stanford study shows. Stanford Report, August 24, 2009. Accessed at http://news.stanford.edu/news/2009/august24/multitask-research-study-082409.html
- Klingberg T. Limitations in information processing in the human brain: neuroimaging of dual task performance and working memory tasks. Prog Brain Res. 2000;126:95-102. Review.
- Meyer D, Kieras D. Multitasking and Task Switching. Accessed at http://www.umich.edu/~bcalab/multitasking.html
- Ophir E, Nass C, Wagner AD. Cognitive control in media multitaskers. Proc Natl Acad Sci U S A. 2009 Aug 24. [Epub ahead of print] doi:10.1073/pnas.0903620106. Accessed at http://www.pnas.org/content/early/2009/08/21/0903620106.abstract
- Szameitat AJ, Lepsien J, von Cramon DY, Sterr A, Schubert T. Task-order coordination in dual-task performance and the lateral prefrontal cortex: an event-related fMRI study. Psychol Res. 2006 Nov;70(6):541-52. Epub 2005 Sep 2.