Brain Limits Capacity for Multitasking, Report Finds

French scientists have discovered the brain's construction limits the ability of humans to make more than two choices at the same time.

While some people may think their ability to multitask comes easily, a report published in the current issue of Science magazine suggests the brain's two lobes automatically divides the ability to do two tasks in half, and the report warned overloading the brain with several tasks simultaneously reduces its ability to function as effectively. The study was authored by Sylvain Charron and Etienne Koechlin of the Institut National de la Sant??« and Ecole Normale Superieure, respectively.

The report noted the brain's anterior prefrontal cortex (APC) gives humans the ability to simultaneously pursue several goals. Koechlin and Charron set out to find how the brain's motivational system, including the medial frontal cortex (MFC), drives the pursuit of these concurrent goals. Using brain imaging, they observed that the left and right MFC, which jointly drive single-task performance, divide under dual-task conditions. "While the left MFC encodes the rewards driving one task, the right MFC concurrently encodes those driving the other task," an abstract of the report explained. "The same dichotomy was observed in the lateral frontal cortex, whereas the APC combined the rewards driving both tasks. The two frontal lobes thus divide for representing simultaneously two concurrent goals coordinated by the APC. The human frontal function seems limited to driving the pursuit of two concurrent goals simultaneously."
In an interview with BusinessWeek, Koechlin said while dual-tasking is fine, tackling three tasks at the same time would overwhelm the brain's frontal function capacity. "Human higher cognition is dual in essence, which can explain why people like binary choice and have difficulties in multiple choices [people can easily switch back and forth between two options before making a decision, but not across three alternatives]," he told the news outlet. "This finding...suggests that the frontal function cannot keep track of more than two goals/tasks at the same time."
This research may help explain the results of a report published in August 2009 from researchers at Stanford University. Scientists there found those likely to experience rigorous daily multitasking are negatively impacting their cognitive state. The report, "Cognitive Control in Media Multitaskers," claimed heavy media multitaskers performed worse on a test of task-switching ability than a group of users who multitasked lightly. The results suggested media multitasking, a rapidly growing societal trend, is "associated with a distinct approach to fundamental information processing."
The research team conducted tests of 262 college undergraduates, dividing them into two groups. Results showed that heavy media multitaskers are more susceptible to interference from irrelevant environmental stimuli and from irrelevant representations in memory. This led to the unexpected result that heavy media multitaskers performed worse on a test of task-switching ability, which researchers concluded was likely due to reduced ability to filter out interference from the irrelevant task set.
While evidence suggests reducing the need for multiple tasks is a health benefit, cutting back on multitasking may not be an easy option for small business owners. A July survey by online payroll specialist SurePayroll found small to medium-size businesses (SMBs) are being forced to do more with less in a constrictive economy, but an increase in multitasking is hurting the quality of service at some midmarket companies. The survey found 88 percent of small business owners think multitasking is now a key component in running a successful business that business owners should embrace.