Perhaps the most obvious characteristic of open-plan offices is that they're designed so that employees must multitask. Even if you're wearing noise-canceling headphones, some part of your brain must always remain alert for opportunities to "collaborate." Even if you're managing to focus on something, you're still surrounded by other people who are multitasking. That's just the nature of the beast.

The assumption behind open-plan offices, of course, is that this "collaboration" makes individuals and teams more "innovative" and "nimble," which basically means "more intelligent." It turns out that multitasking has the exact opposite effect. According to extensive research, multitasking makes you--and the people around you(!)--measurably less intelligent

About a decade ago, organizational psychologists wanted to know whether people who watch multiple media sources (like YouTube and Netflix) simultaneously were training their brains to be better able to multitask when performing various tasks.

The expectation was that young people (who do a lot of media multitasking) would prove to be better suited for working in environments that require multitasking, as in the modern open-plan office.

Surprisingly, the researchers discovered that media multitasking in everyday life does not translate to performance benefits in multitasking tests conducted in a laboratory. In fact, the opposite was the case. Regular media multitasking makes people LESS effective at accomplishing tasks while multitasking.

Meanwhile, a different study at Stanford University discovered that regular multitasking also makes it harder for people to focus on a single task and, perhaps more importantly, "allow[s] goal-irrelevant information to compete with goal-relevant information." In other words, daily multitasking makes you:

  • LESS effective when multitasking.
  • LESS effective when not multitasking.
  • LESS effective at prioritizing to achieve goals.

Why does this happen? Well, it turns out that when you're multitasking, you literally reduce your intelligence, as measured by your ability to comprehend what you're seeing and hearing. A landmark study from York University in the UK found that on a standard comprehension test, multitaskers scored 11 percent lower than those who weren't multitasking.

Even more disturbingly, researchers discovered that merely sitting near somebody who is multitasking drops your comprehension by an astounding 17 percent. This is apparently due to the visual pollution of seeing the other person's screen or activities, which forces your brain to interpret what it's seeing...which takes more effort than the multitasking itself.

To find out what was going on, the psychologists called in the neuroscientists at the Institute of Cognitive Neuroscience at University College London, who scanned the brains of frequent multitaskers. The neuroscientists discovered that multitaskers "had smaller gray matter density in the anterior cingulate cortex," which matched the "observed decreased cognitive control performance."

In other words, daily multitasking--or just being around multitasking--actually does brain damage, making people less intelligent. And, indeed, this squares with personal experience, because anybody who's worked with or lived with habitual multitaskers knows that they tend to be scatterbrained.

The implications of this research are truly frightening, considering that 70 percent of all companies have moved to an open-plan office design, which virtually guarantees that everybody will always either be multitasking or be surrounded by multitasking. Ironically, the very technology that was supposed to make us smarter is actually making us dumber.