Too many times I hear that you can’t survive without multitasking. Checking emails during a meeting, responding to a door knock while trying to focus on your work seems to be a common scenario at the workplace. While many times it pays off to be able to take care of multiple things at once, it would be useful to take a look at our brain to see when it is NOT the best strategy.
Any kind of task that needs a little amount of analysis or decision making is processed in the Pre-frontal cortex (PFC) of the brain. The PFC is a very small and very much energy-hungry part that sits right behind our forehead. If the rest of the brain is like the US economy the size of PFC is like the changes you usually have in your pocket. Between any two tasks if one of them is very rudimentary (something like driving your car in a known street) you can do some other task simultaneously like talking or listening to the radio. But when both the tasks need your PFC you are basically context switching between the two tasks. The more you do the context switching the PFC gets more and more tired. Ultimately its performance starts decreasing, the work quality hampers and you feel exhausted. That fact that the analytic work needs expensive PFC action, by design, we try to avoid those as much as possible. This explains nicely why I would rather answer the door at my office than pay undivided attention to the design problem I am trying to solve. Not to mention, I have checked my Facebook notifications (non-PFC function) two times while writing this post (expensive PFC function)!
So next time you convince yourself that by multitasking you are getting more work done- think again. If you take activity as the synonym of productivity you may get very disappointed when the performance review time comes!