Multitasking – a fancy word for trying to cook 5 courses at the same time; something is going to get burned.

Everyone’s brain is proven to have a deceleration and acceleration time when switching between tasks. This is known as “switching”. The amount of time (the “penalty”) this takes can vary between the task and other factors.

But if you don’t believe this is real, and maybe you’re different and can multitask and this “cognitive switching penalty” doesn’t affect you, try this test. Take two sheets of paper and record how long it takes to write the numbers 1 through 26 on the first sheet, and the letters A through Z on the second sheet.

Then record the time it takes to alternate writing a number on one sheet, and a letter on the second sheet. Your total task time will easily double when you try to switch back and forth between numbers and letters on the two sheets vs just writing one data set at a time.

The shocking part is how much time interruptions can eat up to get back in productive flow. According to a University of California, Irvine study, it’s usually around 23 minutes and 15 seconds to return to the task.

This means you would only have to be interrupted about twice an hour to never be fully on task and productive. And people are typically interrupted every 8-10 minutes on average, leading to easily one of the most expensive problems in the workplace. And not only that, but it leads to more stress, difficulty focusing, and lack of productive work.

So the next time you get a text while working, remember that you can’t “just check it real fast”, but instead to turn your phone off. The penalty imposed on your brain when you switch from your work to the phone, and then back to your work, actually costs 20-25 minutes and not 2-5 minutes.