So reports Larry Rosen, a professor who studies multitasking among students. He recently did a study in which students from middle school through college were told to “study something important, including homework, an upcoming examination or project, or reading a book for a course.” But, as Slate author Annie Paul explains, he and his colleagues found that

it wasn’t long before their attention drifted: Students’ “on-task behavior” started declining around the two-minute mark as they began responding to arriving texts or checking their Facebook feeds. By the time the 15 minutes were up, they had spent only about 65 percent of the observation period actually doing their schoolwork….

Concern about young people’s use of technology is nothing new, of course. But Rosen’s study, published in the May issue of Computers in Human Behavior, is part of a growing body of research focused on a very particular use of technology: media multitasking while learning. Attending to multiple streams of information and entertainment while studying, doing homework, or even sitting in class has become common behavior among young people—so common that many of them rarely write a paper or complete a problem set any other way.

But evidence from psychology, cognitive science, and neuroscience suggests that when students multitask while doing schoolwork, their learning is far spottier and shallower than if the work had their full attention. They understand and remember less, and they have greater difficulty transferring their learning to new contexts. So detrimental is this practice that some researchers are proposing that a new prerequisite for academic and even professional success—the new marshmallow test of self-discipline—is the ability to resist a blinking inbox or a buzzing phone.

The article goes on to discuss a number of other studies on multitasking in the classroom and while studying, and describes

a cascade of negative outcomes that occurs when students multitask while doing schoolwork. First, the assignment takes longer to complete, because of the time spent on distracting activities and because, upon returning to the assignment, the student has to refamiliarize himself with the material.

Second, the mental fatigue caused by repeatedly dropping and picking up a mental thread leads to more mistakes…. Third, students’ subsequent memory of what they’re working on will be impaired if their attention is divided…. Fourth, some research has suggested that when we’re distracted, our brains actually process and store information in different, less useful ways…. Finally, researchers are beginning to demonstrate that media multitasking while learning is negatively associated with students’ grades.

Well worth reading.