Texting, emailing, and posting on Facebook and other social media sites are by far the most common digital activities students undertake while learning, according to Rosen. That’s a problem, because these operations are actually quite mentally complex, and they draw on the same mental resources—using language, parsing meaning—demanded by schoolwork.

“Under most conditions, the brain simply cannot do two complex tasks at the same time. It can happen only when the two tasks are both very simple and when they don’t compete with each other for the same mental resources. An example would be folding laundry and listening to the weather report on the radio. That’s fine. But listening to a lecture while texting, or doing homework and being on Facebook—each of these tasks is very demanding, and each of them uses the same area of the brain, the prefrontal cortex.”

“there’s nothing magical about the brains of so-called ‘digital natives’ that keeps them from suffering the inefficiencies of multitasking. They may like to do it, they may even be addicted to it, but there’s no getting around the fact that it’s far better to focus on one task from start to finish.”

mental fatigue

takes longer

negatively associated with students’ grades