04/19/2016 01:24 pm ET Updated Apr 20, 2017

Multitasking Doesn't Work

Common wisdom says that we get more done by multitasking.
It's not true. Consider these three points.

1. The Brain Does Not Multitask

The brain isn't built for multitasking. In fact, it can only do one thing at a time.

Adding tasks doesn't expand the brain's capacity; it only increases its cognitive load, or the amount of mental effort it must put out. By multitasking we are reducing the attention we give to each thing.

A 2013 study shows that high cognitive load severely impairs performance, especially when accurate and complex judgments are needed. Another study says that if you increase the number of things to which the brain needs to pay attention, it results in bottlenecks that can block awareness of important information and disrupt your ability to make decisions.

In short, doing two or more tasks at once usually leads to impairment in at least one of them.

2. We Multitask for the Wrong Reasons

If multitasking doesn't deliver our best performance, why do we do it?

Multitasking makes us look and feel productive. Processing tasks and crossing things off our To Do list feels good, and most of us will choose feeling good over being efficient and effective in the long term.

Being more selective about what we do--prioritizing--takes time and effort, and the results aren't immediately visible. We don't want to be perceived as lazy or unproductive.

Prioritizing is a risk. It means placing your bets on a few things and disregarding others for the time being. It feels safer to do a little bit of everything.

3. We Don't Need to Do More, We Need to Do What Matters Most
Multitasking can make all tasks seem equally important; it doesn't allow us to consider each deeply or assess their relative value. This can lead to simply reacting to an in-box of problems as they arrive instead of drilling down to their root causes and solving them.

When we multitask, it's easy to mistake productivity--doing a lot of things--for contribution--solving problems and making progress. Staying busy and checking off tasks doesn't necessarily get us closer to our larger goals. It's particularly destructive if we use our busyness to put off tackling the most difficult issues, the ones we're afraid will take too long or will be too difficult to solve.

Rather than doing as much as possible, we need to choose the one thing that will contribute the most today to accomplishing our goals. This feels uncomfortable and risky, but our best work is done when we give our full attention to the one thing that makes the most difference.

Multitasking can actually keep us from making solid progress toward our goals. It's better to give up the appearance of busyness for the reality of achievement.