Human Multitasking - The Brain's Role

The Brain's Role

Because the brain cannot fully focus when multitasking, people take longer to complete tasks and are predisposed to error. When people attempt to complete many tasks at one time, “or rapidly between them, errors go way up and it takes far longer—often double the time or more—to get the jobs done than if they were done sequentially,” states Meyer. This is largely because “the brain is compelled to restart and refocus”. A study by Meyer and David Kieras found that in the interim between each exchange, the brain makes no progress whatsoever. Therefore, multitasking people not only perform each task less suitably, but lose time in the process.

When presented with much information, the brain is forced to pause and refocus continuously as one switches between tasks. Realistically, this is “a rapid toggling among tasks rather than simultaneous processing.” According to a study done by Jordan Grafman, chief of the cognitive neuroscience section at the National Institute of Neurological Disorders and Stroke, “the most anterior part allows to leave something when it’s incomplete and return to the same place and continue from there,” while Broadman’s Area 10, a part of the brain’s frontal lobes, is important for establishing and attaining long term goals. Focusing on multiple dissimilar tasks at once forces the brain to process all activity in its anterior. Though the brain is complex and can perform a myriad of tasks, it cannot multitask well.

Another study by René Marois, a psychologist of Vanderbilt University, discovered that the brain exhibits a “response selection bottleneck” when asked to perform several tasks at once. The brain must then decide which activity is most important, thereby taking more time. Psychologist David Meyer of the University of Michigan claims that, instead of a “bottleneck,” the brain experiences “adaptive executive control” which places priorities on each activity. These viewpoints differ in that, while bottlenecking attempts to force many thoughts through the brain at once, adaptive executive control prioritizes tasks to maintain resemblance of order. The brain better understands this order and, as psychologists such as Dr. Meyer believe, can therefore be trained to multitask. Because the brain is an expanse of yet uncharted territory, psychologists do not understand how the brain truly processes input and reacts to overstimulation.

Some research suggests that the human brain can be trained to multitask. A study published in Child Development by Monica Luciana, associate professor of psychology at the University of Minnesota, discovered that the brain’s capability of categorizing competing information continues to develop until ages sixteen and seventeen. Perhaps if people are trained to multitask at an early age, they will become efficient at multitasking. A study by Vanderbilt University found that multitasking is largely limited by “the speed with which our prefrontal cortex processes information.” Paul E. Dux, co-author of the study, believes that this process can become faster through proper training. The research team found that with training, the brain can think and perform certain tasks more quickly, effectively allowing time for another task. The study trained seven people to perform two simple tasks, either separately or together, and conducted brain scans of the participants. The individuals multitasked poorly at first but, with training, were able to adeptly perform the tasks simultaneously. Brain scans of the participants indicate that the prefrontal cortex quickened its ability to process the information, enabling the individuals to multitask more efficiently. However, the study also suggests that the brain is incapable of performing multiple tasks at one time, even after extensive training. This study further indicates that, while the brain can become adept at processing and responding to certain information, it cannot truly multitask.

People have a limited ability to retain information, which worsens when the amount of information increases. For this reason people alter information to make it more memorable, such as separating a ten-digit phone number into three smaller groups or dividing the alphabet into sets of three to five letters. George Miller, former psychologist at Harvard University, believes the limits to the human brain’s capacity centers around “the number seven, plus or minus two.” An illustrative example of this is a test in which a person must repeat numbers read aloud. While two or three numbers are easily repeated, shown in the beginning straight line, fifteen numbers becomes more difficult, as the line curves. The person would, on average, repeat seven correctly. Brains are only capable of storing a limited amount of information in their short term memories.

This ineffectiveness of the human brain for multitasking has been demonstrated in different studies.

Laboratory based studies of multi-tasking indicate that one motivation for switching between tasks is to increase the time spent on the task that produces the most reward (Payne, Duggan & Neth, 2007). This reward could be progress towards an overall task goal or it could simply be the opportunity to pursue a more interesting or fun activity. Payne, Duggan and Neth (2007) found that decisions to switch task reflected either the reward provided by the current task or the availability of a suitable opportunity to switch (i.e. the completion of a subgoal). A French fMRI study published in 2010 indicated preliminary support for the hypothesis that the brain can pursue at most two goals simultaneously, one for each frontal lobe (which has a goal-oriented area).