The Hidden Cost of Context Switching

The Myth of Multitasking

It is a myth that doing more than one task simultaneously is a productive use of time. This really shouldn’t surprise anyone who has attempted talking on the phone while checking their e-mail, or (even worse) talked on a cell phone while driving. Nevertheless, the extent of this problem may be quite shocking.

Psychologists have studied what happens to mental processes when people attempt to perform more than one task at a time, and have discovered that the human mind has not been designed for complex multitasking. The effects of multitasking come into play when someone tries to perform two or more tasks at the same time by switching from one task to another, but also when performing two or more tasks in quick succession.

By comparing how long it takes for people to get everything done, psychologists conduct task-switching experiments to measure the productivity costs that this kind of mental “juggling” demands. They also look into the effects different features of the tasks have, including how complex or familiar each task is.

The cost of switching may be relatively small, often just a few tenths of a second per switch. But the cost of each switch can add up to large amounts, especially when switching repeatedly back and forth between tasks. This can cause multitasking to seem artificially efficient when, in reality, tasks are actually taking more time to complete, and the likelihood of error also increases. Research has suggested that even brief mental blocks created by switching between tasks can cost as much as 40% of an individual’s productive time.

The Cost of Context Switching

A proposed rule of thumb by Gerald Weinberg illustrates that adding even a single simultaneous project to your workload will be deeply debilitating to productivity. As illustrated below, adding one extra project will cause you to lose 20% of your time. Adding a third project will waste nearly half of your time to context switching.

This can be a problem even when you are ostensibly working on a single project. The impact of simply answering your phone, checking email and responding to every ping of your mobile phone can be profound.

Reduce the Effects of Context Switching

We generally overestimate how much we can realistically get done in a certain amount of time, and multitasking serves to exaggerate this internal bias even more. Whenever possible, it is advisable to avoid all interruptions, and also to avoid working on more than one project simultaneously. Now, I do live in the real world, and so I understand that this is not always possible. So when distractions and multiple projects are unavoidable, make sure you are brutally honest with yourself and anyone else dependent on your work about exactly how much time you will need. It’s probably more than you think.

Unfortunately, context switching is often unavoidable, so it is important to lessen its effects before they hold you back.

1. Keep Track of Where You Left Off

When you have to switch between the same two or three projects several times, it is easy to get your thoughts confused and disorganized. Before switching to the next task, take a few minutes to note where you were on a project and what your thought process was when you stopped.

Important things to note may be:

1. What you have accomplished
2. What aspects still need to be completed
3. Any next steps that are necessary (e.g. follow-up email, further research, etc.)

This will serve as a quick reference and help put you into the correct frame of mind for when you inevitably switch back to the task.

2. Prioritize and Switch Less Often

There are a few techniques you can use to reduce the number of context switches you make in a given period, such as prioritization and time blocking. As inevitable distractions pop up throughout the day, resist the urge to delve right into the problem.

Assess whether the distraction is a priority and set a time to address it. Knowing that you have time set aside for making a change or calling a client back will allow you to focus on your current task.

3. Make Use of Lists

Having a single list of all pending tasks for each project will take some of the load off of your mind. Comprehensive lists are a valuable visualization of exactly how much work is required.

Lists can also help organize the tasks within each project to avoid context switching within the projects themselves. Similar tasks can be grouped together in order to tackle them all at once.

Remember that lists are only as useful as they are accurate, so be sure to update and trim the list as needed.

4. Switch Environments When You Switch Tasks

If you must make mental switches throughout the day, try to create a complete switch. When possible, move to another desk or room, sit at a couch with your laptop, or head down to the nearest coffee shop for an hour. Use the physical change to clear your mind of the recent project so you can clearly change your focus.

If you cannot change your environment completely, take a short break. Get up from your seat and walk around a bit before starting up your new context.

If multitasking and context switching are inescapable parts of your day, do yourself a favor and regain control over how much time you spend context switching.