Neural Basis of Multitaskingby Viatcheslav Wlassoff, PhD | November 19, 2015
Multitasking – the ability to perform two or more different tasks at once – is viewed by many as a very useful skill, important for succeeding in professional development. Some people are better in handling several tasks at once, while others are not. But the reason for this difference is not that clear.
Why some people can check their email, receive phone calls and write down stuff, while others get mad and disturbed when somebody talks to them while they are trying very hard to fry an egg? The clear answer to this question has not yet been found, and neuroscientists are still trying to uncover the full set of complex mechanisms behind multitasking. Nevertheless, some interesting facts have recently emerged that deserve our attention.
How the brain processes information
Before talking about the possible mechanisms of multitasking, it is of crucial importance to understand that when a person is struggling to complete two or more tasks, the brain does not really process all the given information at once, as many might think.
Instead, it constantly switches from one task to another. According to fMRI data, the switching action itself occurs in Brodmann’s area 10 (anterior prefrontal cortex). The experiments demonstrate that the anterior prefrontal cortex grants us the ability to put the information from one task on “hold” with the ability to return to it and continue fulfilling it from the point where it was left.
The latest study on this matter performed by German researchers involved 344 participants which had to switch between working memory tasks. In this experiment, the participants were shown the sequence of numbers appearing on a screen one after another, and were asked to press a button which corresponded to the numbers shown two places back. The participant needed to keep the numbers in their head and find the right buttons to press. The brain activity was recorded with the help of an fMRI and the results confirmed the crucial involvement of the anterior prefrontal cortex in the successful fulfillment of the task.
However, multitasking slows us down and decreases the productivity of work. Probably the best illustration to this is the case of a 27-year-old French women who was “nominated” for the Darwin Award in 2002. The woman crashed her car because she was trying to urgently “feed” her beeping Tamagotchi key ring while driving on the highway.
Switching between two tasks clearly leads to lack of concentration. Another fact worth mentioning is that multitasking is associated with negative changes in the brain’s gray matter. A recent study demonstrated a decrease of gray matter while multitasking with media.
In this study, 75 adults answered a set of question regarding how much they use media devices, and then had their brains scanned by fMRI. The results showed a decrease of gray matter density in the anterior cingulate cortex in those people who used media often, a thing which could not be said for those who used media more rarely. A small number of similar experiments has been made before that one and demonstrated similar results.
Unfortunately there is no clear answer to the question why some people can multitask easily while others struggle to do so. But what can be said is that everyone’s brain is different. It was demonstrated, however, that multitasking can get better with training.
In 2014, a research group from the University of Montreal has done an interesting experiment. Scientists asked a group of senior citizens to perform two different tasks. The participants had to devote a certain amount of time to one exercise and then smaller amount of time to the other (in a ratio of about 80:20). The brain activity was recorded by fMRI and the results revealed the increased activity of the anterior prefrontal cortex.
So if it is true that multitasking capability can be trained, then it is possible that some people unconscicously train their brain more than others. The other possible explanation would be that some people have more developed and active anterior prefrontal cortex from birth.
The opinion that women are better at multitasking is often expressed by psychologists. There is, however, an acute shortage of evidences to prove this statement, as most studies on multitasking were done on mixed cohorts without making comparisons between genders.
Nonetheless, an interesting study in 2013 demonstrated showed that men’s brains displayed better connections inside each hemisphere (from front to back) whereas in women the connections between hemispheres were better. The findings may provide certain support to the view that women are better in multitasking while men are better at heavily concentrating on a single task. Most certainly, more studies are needed to clarify this question, though.
Belleville, S., Mellah, S., de Boysson, C., Demonet, J., & Bier, B. (2014). The Pattern and Loci of Training-Induced Brain Changes in Healthy Older Adults Are Predicted by the Nature of the Intervention PLoS ONE, 9 (8) DOI: 10.1371/journal.pone.0102710
Bier, B., de Boysson, C., & Belleville, S. (2014). Identifying training modalities to improve multitasking in older adults AGE, 36 (4) DOI: 10.1007/s11357-014-9688-2
Braun, U., Schäfer, A., Walter, H., Erk, S., Romanczuk-Seiferth, N., Haddad, L., Schweiger, J., Grimm, O., Heinz, A., Tost, H., Meyer-Lindenberg, A., & Bassett, D. (2015). Dynamic reconfiguration of frontal brain networks during executive cognition in humans Proceedings of the National Academy of Sciences, 112 (37), 11678-11683 DOI: 10.1073/pnas.1422487112
Dreher, J., Koechlin, E., Tierney, M., & Grafman, J. (2008). Damage to the Fronto-Polar Cortex Is Associated with Impaired Multitasking PLoS ONE, 3 (9) DOI: 10.1371/journal.pone.0003227
Loh, K., & Kanai, R. (2014). Higher Media Multi-Tasking Activity Is Associated with Smaller Gray-Matter Density in the Anterior Cingulate Cortex PLoS ONE, 9 (9) DOI: 10.1371/journal.pone.0106698
Rishel, C., Huang, G., & Freedman, D. (2013). Independent Category and Spatial Encoding in Parietal Cortex Neuron, 77 (5), 969-979 DOI: 10.1016/j.neuron.2013.01.007
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