Dangers of Multitasking & Memory | Mental Health Blog

Multitasking Kills Memory and Productivity


Article Summary:

  • The term “multitasking” was first used in 1965 to describe capabilities of an IBM computer. With the increase in media now available to individuals, human multitasking (e.g., using several media streams at once) has become commonplace.
  • While it may appear that multitasking is an efficient way to get things done, studies indicate otherwise and, in fact, show that multitasking may impair attention and memory.
  • It’s unknown whether a brain impacted by multitasking can recover its former ability to focus and memorize. Taking steps to limit simultaneous media exposure is the only known solution.

Is Multitasking a New Phenomenon?

Multitasking means doing more than one thing at a time. Author Greg McKeown notes, in his book Essentialism, that prior to the 20th Century, the word “priority” had no plural form in English. A priority was the one thing you focused on, period. But in the 1900s, as people were faced with more choices and industrialization made us more mobile, we found we had more than one “priority” at a time and had to rank order, and so the word “prioritize” came into the language.

It’s noteworthy that UCLA Professor Monica Smith contends, in her book A Prehistory of Ordinary People, that our prehistoric ancestors multitasked, but she’s talking about things like picking fruit while watching out for attacking animals.1Smith, Monica L. A Prehistory of Ordinary People. University of Arizona Press.2010. Most would argue that the mental demands of modern-day multitasking—talking on the phone while cruising E-Bay, for instance—are of a different order.

Prevalence of Extreme Multitasking

Since the advent of portable devices and personal computers, multitasking has taken on new meaning. In the mid Twentieth Century, multitasking meant things like washing the dishes while watching As The World Turns. But now, according to Dr. Clifford Nass of Stanford University, “The top 25 percent of Stanford students are using four or more media at one time whenever they’re using media. So, when they’re writing a paper on their computer, they’re also Facebooking, listening to music, texting, Twittering, etcetera.”2“The Myth of Multitasking.” 10 May 2013. NPR. 4 September 2019. http://www.npr.org/templates/transcript/transcript.php?storyId=182861382 The difference isn’t merely in the number of activities they’re involved in at one time but also in the type of attention required. Washing dishes can be done without much mental concentration, but texting, Facebooking, reading Twitter messages—these things require left-brained focus.

Dr. Anthony Wagner of Stanford University, a leading researcher in the field of multitasking and memory, explains that we aren’t actually capable of true multitasking, but rather, we “task switch.” Those who “multitask” might watch a TV show but check their phone during a commercial. In contrast, a heavy multitasker might be writing a paper with the TV on, checking Facebook every five minutes, and responding to emails or texts as they come in.

A study published by the National Academy of Sciences found that youth under the age of 18 spend an average of nine hours a day using media, and 29 percent of that time, they’re using multiple media streams at once. And a 2018 study investigating the accuracy of telephone surveys determined that more than half of respondents were engaged in at least one other online activity while taking the survey.

Likewise, a 2003 study in the International Journal of Information Management reported that the average person checks email once every five minutes. Even more, after checking email, it takes a little over a minute to resume the previous task. And as we’ve written before, most of us disconnect from email for only two hours a day, at most.

What Multitasking Does to the Brain

When you have a task to do, your brain’s prefrontal cortex hops into action. It coordinates the left and right sides of the brain with other neurological processes to create the needed focus. When you attempt to do several tasks at the same time, the prefrontal cortex splits up the tasks between the right and left hemispheres. It takes a minute for the brain to recover enough to coordinate the two hemispheres so that complete focus can resume, as noted above in the description of what happens after checking email. Experts call this lost time the “switching cost.” Studies show that the switching cost can lead workers to lose up to 40 percent of their productivity.

Cognitive Effects of Multitasking

According to Dr. Nass, who wrote The Man Who Lied to His Laptop, “The research is almost unanimous, which is very rare in social science, and it says that people who chronically multitask show an enormous range of deficits. They’re basically terrible at all sorts of cognitive tasks, including multitasking.”

A recent study on multitasking published in the 2018 Proceedings of the National Academy of Sciences reviews 10 years of studies on the effects of multitasking on cognitive performance. The researchers confirmed that heavy multitaskers do indeed perform significantly worse on memory tasks as well as on attention tasks. Dr. Nass says that media multitasking actually changes the brain by training the brain to “focus on irrelevancy. [Multitaskers] just can’t keep on task.” He also says that it’s unknown if the brain that’s been trained to task switch can be trained back to have good focus because it’s too difficult to find subjects willing to give up media for a long enough time to complete clinical studies.

How to Avoid the Negative Effects of Multitasking

The easiest way to prevent brain changes caused by media multitasking is to turn on only one device at a time and shut down extra windows. Other simple changes can make a big difference, too.

  • Turn off all notifications, whether they ding, ping, or flash across the screen and do so on all your devices, including your phone.
  • Set your timer for 15 or 20 minutes and do only one thing for that entire duration.
  • Process your emails in batches so that you spend 20 minutes, for instance, looking at all your emails for the day and then later another 20 minutes responding. Avoid peeking between designated email sessions to check what’s come in.
  • If you have writing to do, go somewhere that has no internet connection—or simply turn off your internet connection while working.
  • If it’s possible for you, go on a media fast and take note of how you feel and whether you notice differences in your ability to concentrate.



1 Smith, Monica L. A Prehistory of Ordinary People. University of Arizona Press.2010.
2 “The Myth of Multitasking.” 10 May 2013. NPR. 4 September 2019. http://www.npr.org/templates/transcript/transcript.php?storyId=182861382