The iconic bullying boss has to be Mr. Dithers, Dagwood Bumstead's nemesis in the long-running comic strip Blondie. Mr. Dithers is blustery, mean, stingy with praise and money, and both physically and emotionally abusive. And he's gotten away with his intolerable behavior for more than 70 years. (Click here to follow Wray Herbert)

It's no wonder that so many readers sympathize with the hapless Dagwood even today. A recent survey reveals that a startling 37 percent of the country's workforce—some 54 million people—have bosses who scream at them, belittle them, sabotage their work, and are otherwise aggressive. Social scientists and policymakers are very concerned about this toxic phenomenon, if only because of the enormous personal and economic costs. It's hard for people to do their best work when they are busy trying to avoid the office ogre.

So why are workplace tyrants so common? What's the psychological dynamic underlying such dysfunction at the top? It's not simply the power; there are many powerful bosses who are good and decent—or at least tolerable. Power corrupts only some—but which ones and why? Two psychologists recently decided to explore one possible explanation: perhaps it is power, but only power mixed with incompetence, that leads to aggression and abuse.

Nathanael Fast of the University of Southern California and Serena Chen of the University of California, Berkeley, ran a series of experiments to test this theory in different ways. In one, for example, they drew a sample of volunteers from a massive database of American workers, with a diverse array of jobs and careers and workplaces, and gave them a battery of psychological tests. These instruments have been used and refined over many years, and are designed to hide their true purpose, which is to measure certain psychological traits that people wouldn't necessarily want to reveal, specifically: feelings of inadequacy and incompetence and aggressive tendencies, both verbal and physical.

They also gathered information on how much formal authority and power each volunteer actually exercised in the workplace. The idea was to see if indeed power and feelings of incompetence interact in creating an intolerable boss. And that's precisely what they found: people who felt inadequate were abusive only if they also were in positions of power, and powerful people were mean and aggressive only if they suffered from self-doubts. Neither power nor incompetence was enough by itself to turn a boss bad, just the combo.

It won't surprise a lot of workers to learn that their mean-spirited supervisor has secret feelings of inadequacy. But the researchers wanted to double-check these results, so they did a laboratory simulation of the workplace dynamic. They used what are called "primes" in the jargon of the field: they had some volunteers write about a time in the past when they felt particularly powerful, an exercise which is known to activate these internal feelings. Some of these empowered workers also recalled and wrote about a time when they performed admirably at some task, while others wrote about a past experience of inadequacy. As a laboratory measure of aggression, they created a ruse in which the volunteers had to choose how much noise to blast at a stranger, ranging from completely benign to head-rattling.