The human brain is always multitasking. That doesn’t mean we’re good at it

The human brain switches its attention constantly because it can’t focus on two things at once. Multitasking works until a task needs concentration.

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Two tasks can run simultaneously, unless they need the same part of the brain or body. Walking and chewing gum, for example, can be done at the same time because they use different body parts and don’t require a lot of concentration. But texting and driving both need the same pair of eyes.

And the front of the brain, which handles focus, does one thing at a time, so tasks that need it take turns. This is when multitasking takes a toll. It’s called switch cost, when the brain takes a moment or two to recover from switching between information competing for attention,

Reading while someone talks to you can feel like doing two things at once. But John Paul Minda, a psychology professor at Western University, said much of what people call multitasking comes down to the brain switching between sources of information. And there is always some cost to that, he said.

The human brain takes in lots of things at once, “because we don’t know what the important information is until we’ve processed it,” he said. “The idea of jumping around is just something that your brain does whether you want it to or not.”

People who multitask a lot and think they are good at it are actually worse at it when they need to focus on two things. That’s because “you’re kind of used to shifting your attention really quickly,” Minda said. Each shift takes “a few seconds or half a second” to recover, he said.

Maximilian Riesenhuber, a professor of neuroscience at Georgetown University Medical Center, said some multitasking comes naturally and others, like tying your shoes while you talk, can become automatic with practice. “You can walk and chew gum, right? I mean, some things we can do naturally in parallel.”

Riesenhuber, along with Patrick Cox, an assistant professor of psychology at Lehigh University, led a study published this year in the Journal of Cognitive Neuroscience that tested whether practice could make a new task automatic. The 11 people in the test practiced sorting pictures of cars into two groups on a phone app, more than 30,000 times over five to 10 weeks. Brain scans were taken before and after the test.

Before the study, Riesenhuber said the accepted view was that practice made people better at switching between tasks, while the prefrontal cortex, at the very front of the brain, kept doing the work. After the test, the scans showed the sorting-cars task had moved to the temporal cortex, a region he said “does a lot for vision.”

“You kind of build a little program,” Riesenhuber said, “and then you send it to the other part of your brain, and then that takes over for that task.”

Cox called the finding “a proof of concept” in an email to National Post. Once trained, he wrote, some participants sorted the cars just as well with a second task added as they did without the additional task.

But practice won’t make texting and driving work together any easier, Riesenhuber said, because you can only look at one thing at a time. “I don’t want people to think, oh yeah, I do texting and driving a lot and that’s going to work,” he said. “I mean it’s just not going to work because you look at different places.”

How many other tasks can be combined with training “is an exciting open research question,” Cox wrote.

In the health-care field, multitasking often isn’t a choice. A pharmacist who is constantly being interrupted with calls could fill the prescription incorrectly.

“It is common for people to multitask, but this is at-risk behaviour as it increases the risk of error,” Natalie Borden, CEO of the Institute for Safe Medication Practices Canada, said in an email to National Post. The organization analyzes reports of medication incidents, including near misses.

Pharmacies in participating provinces reported more than 27,600 medication incidents last year, an increase of six per cent over the year before. Environmental, staffing and workflow problems were the top contributing factors in 2024 and 2025, with interruptions “a large proportion of that,” Borden wrote. She called the problem “a system issue, and not an individual practitioner issue,” since frequent interruptions and unpredictable workloads are “not within the control of individual staff members.”

Checking a phone at dinner or during a movie is multitasking. Minda said people handle quick shifts of attention well but struggle to stay focused on one thing, “because your brain is always looking for the next thing.”

One lab test of multitasking has people remember strings of letters while solving simple math problems. In a study published in 2022, Minda’s lab tried to repeat an experiment that found a phone on the desk made students worse at the test by competing for their attention.

“Having the phone on your desk or in your bag didn’t seem to make you any worse,” he said.

He suspects students had learned to cope after years of being told to put their phones away in school. “If I tested people now,” Minda said, “I might find a different result.”

He got through high school and university with no device competing for his attention. Now most people have one, he said, but “unfortunately, our multitasking abilities are about the same, and humans are still really distractible.”

People can manage the distractions from devices, because texting or scrolling TikTok while studying is voluntary, said Allison Drody, a postdoctoral research fellow in psychology at Queen’s University in an email to National Post. “We have some choice over when we multitask and with what activities.”

Someone at a desk in an office, for example, could turn off nonessential notifications during work hours to reduce the temptation to multitask.

Minda said most people, himself included, have trouble looking away from their device when they have nothing else to look at.

“We’re good at multitasking,” Minda said. “The brain loves to multitask. It’s just not always good for us.”

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