One thing at a time and that done best - this is one of the oldest pieces of advice handed down from generation to generation. This would be ideal if life politely waited for us to finish one task before sending another our way, or if we had few tasks to complete in an abundant amount of time. Unfortunately, life is not ideal.
Have you ever been in a moving vehicle when it made a sudden start or stop? Or, how about getting on or off a moving vehicle? In either case, your body takes a little time to get used to the sudden change of momentum. Without the time to get used to the sudden change in momentum, or without something to hold on to when such sudden changes occur, you will lose your balance and fall over. This is a demonstration of Newton's First Law of Motion - "Every body at rest or in uniform rectilinear motion remains at rest or in uniform rectilinear motion unless acted on by an external force". This law is otherwise known as the law of Inertia.
Automatic Time Set Clock
The mind is not very different. It works by associations. The term "train of thought" is very accurate - it follows a track, most often a track it has followed through before, and moves with a high momentum. Switching the mind from one track of thought to another requires slowing down this train and moving to the other track. When the train of thought gets forcibly switched by an abrupt interruption, it even gets derailed. The more disparate the thoughts (and trains) are, the greater the effort it takes to switch from thought to thought. If switching thoughts take so much effort, how about switching tasks that take thought?
Switching from task to task or thought to thought is referred to as "context switching". The brain "normally" operates by following associations within a context. It either follows existing links or creates new ones. It operates at a very high speed: By the time one gets to recognize a particular association, the brain scans ahead several thousand more. It sets up a queue of associations to be "followed" next in sequence. Context switching breaks these associations. The brain is forced to discard the queue of associations and to rescan for new ones. It also takes some time to come up to speed to scan thousands of associations ahead.
Consider a computerized photograph-printing machine in one of the 1-hour photo shops. These machines have a finite setup time. They are normally set for a certain size of print, and all the jobs that require that size are scheduled for that run. Other sizes are handled similarly. This makes the operation very efficient. If, on the other hand, the jobs were scheduled in the order in which they were accepted, the machine would potentially have to be reset after every job. Given the setup time, the operation would become very inefficient.
Similarly, context switching causes multiple setup times and is very inefficient on the mind. The cost of multi-tasking, especially with regard to tasks that require conscious thought, is inefficiency.
Adam Smith (The Wealth of Nations, 1776) recognized the "saving of time which is commonly lost in passing from one species of work to another". This is the biggest benefit of avoiding multi-tasking. "Passing from one task to another" is "context-switching". Adam Smith recognized as long ago as 1776 that time is "commonly lost" in context switching. "Division of labor" reduces context switching and, consequently, the time lost due to context switching
In short, context switching is bad. It is efficient to do one thing at a time and take it to completion before moving to another task.
Sometimes, you have to juggle more than one task at the same time. Life is not polite. It does not stand politely by and wait for you to finish the task at hand before throwing the next task at you. Certain situations may demand immediate attention. People who wear "multiple hats" and have several responsibilities need to multitask. What do you do under such conditions?
While it is recognized that context switching and multitasking introduce a certain element of inefficiency, it is also necessary under certain conditions. We rarely, if ever, have the luxury of focusing totally on one task for its entire duration. We constantly get interrupted, and, depending on the nature of the interruption, our priorities may change.
Do you think about everything that you do or do you sometimes operate on autopilot?
Do you remember how you were taught to tie your shoelaces? You may have had to focus on the steps until you were able to do it without thinking about it.
Do you think about walking? Can you walk and chew gum at the same time?
My point is that with sufficient practice, some mechanical tasks can be delegated to the automatic section of the mind at which time you can put your mind to work on something else. You can, for example, plan your Power Point presentation (or something thought consuming) while tying your shoelaces (or something equally trivial).
There are some tasks which inherently require us to do multiple things simultaneously. For example, a person playing a musical instrument may be doing three or four things at the same time. It has been observed that musicians can multitask very well.
Human beings do multitask naturally. When a mechanical task is done over and over again, it is no longer handled by the thinking part of the brain, the gray matter or cerebrum. It moves into the automatic part of the brain, the white matter or cerebellum. Automatic tasks, when sufficiently practiced, may be combined with other automatic tasks or at most one task requiring thinking.
It takes practice to move any action from the thinking area to the motor area of the brain. It takes more practice to combine actions. Only automatic actions can be multitasked. If you expect to take any specific action over and over again, practice it so that you do not have to think about it. For example, musicians, martial artists and sports personages constantly practice their actions to be able to execute them flawlessly.
The ability to multitask will help us cope with interruptions and changing priorities. In addition, multitasking, if practiced well, will greatly improve our throughput.
The benefits of multitasking include:
1. The ability to switch between tasks when one is charged with multiple responsibilities,
2. Greater throughput while handling mechanical (automatic, thought-free) tasks.
Multitasking can improve productivity and throughput. However, not all tasks may be combined with other tasks.
We all do a certain amount of multitasking anyway. For instance, you may scan the newspaper while drinking your morning coffee, or listen to the radio while driving in to work. It is as easy as walking and chewing gum at the same time! Most of these tasks are mechanical. While multitasking in this manner, the brain is actively monitoring only one task, or at most one task. The other tasks run in the back of the mind.
Time Management - The Benefits of Multitasking