We live in a time that worships attention. When we need to work, we force ourselves to focus, to stare straight ahead at the computer screen. There's a Starbucks on seemingly every corner—caffeine makes it easier to concentrate—and when coffee isn't enough, we chug Red Bull.

In fact, the ability to pay attention is considered such an essential life skill that the lack of it has become a widespread medical problem. Nearly 10% of American children are now diagnosed with attention-deficit hyperactivity disorder (ADHD).

In...