Many young people multitask to the extreme, particularly when it comes to media consumption. I’ve witnessed my twenty-two-year-old brother watch television while talking on the phone, IMing with several friends, composing an e-mail, and updating his Facebook page. A widely cited 2006 study by the Henry J. Kaiser Family Foundation found that 81 percent of young people engage in some form of media multi-tasking during a given week. But as cognitive psychologists have long known, human attention is quite limited. Despite our best efforts, when we try to do more than one thing at once, we are less efficient and more prone to error. This is because multitasking is actually a process of dividing attention, of toggling back and forth between tasks.

Acquiring new information requires particularly focused attention, which includes the ability to ignore distractions. In order to absorb the information contained in a CNN newscast, for example, we must not only direct our attention to the person talking, but also filter out the running headlines, news updates, and financial ticker on the lower part of the screen. Torkel Klingberg, a professor of cognitive neuroscience at Karolinska Institute in Sweden and author of The Overflowing Brain, puts it simply: “If we do not focus our attention on something, we will not remember it.” In other words, attention is a critical component of learning.

Michael Posner, a researcher who has dedicated his career to studying attention and a professor emeritus of psychology at the University of Oregon, explains attention as a system of three networks—alerting, orienting, and executive. Alerting refers to the state of wakefulness necessary to attend to information, while orienting is the process by which we respond to stimuli, such as movement, sound, or noise. Executive attention is the highest-order network, the one that we have conscious control over. If we are trying to study for a test or read a novel, we use it to direct and maintain our focus, as well as to suppress our reaction to competing stimuli like the din of a nearby conversation or television.

The information-saturated environment that we live in is, unsurprisingly, extremely demanding of our attention. Modern life—both at work and at home—has become so information-rich that Edward Hallowell, a Boston-area psychiatrist, believes many of us suffer from what he calls an attention-deficit trait, a culturally induced form of attention-deficit disorder. As he pointed out in a 2005 interview with CNET News, “We’ve been able to overload manual labor. But never before have we so routinely been able to overload brain labor.” According to Hallowell and other psychiatrists, all these competing inputs prevent us from assimilating information. “What your brain is best equipped to do is to think, to analyze, to dissect, and create,” he explains. “And if you’re simply responding to bits of stimulation, you won’t ever go deep.” Journalist John Lorinc noted as much in an elegant article on distraction in the April 2007 issue of The Walrus:

It often seems as though the sheer glut of data itself has supplanted the kind of focused, reflective attention that might make this information useful in the first place. The dysfunction of our information environment is an outgrowth of its extraordinary fecundity. Digital communications technology has demonstrated a striking capacity to subdivide our attention into smaller and smaller increments; increasingly, it seems as if the day’s work has become a matter of interrupting the interruptions.

In a recent report, Information Overload: We Have Met the Enemy and He Is Us, the research firm Basex concluded that interruptions take up nearly 30 percent of a knowledge worker’s day and end up costing American businesses $650 billion annually. Other studies show that interruptions cause significant impairments in performance on IQ tests.

Bree Nordenson a former assistant editor of CJR.