(FORTUNE Magazine) – For more than a decade, executive-development consultant Richard Hagberg has been advising chief executives on the fine points of leadership. His firm, the Hagberg Consulting Group, has compiled a database on the characteristics of 511 CEOs that delivers intriguing insights into why so many fail to inspire loyalty in their troops. Based on CEO personality tests and evaluations from thousands of their co-workers, Hagberg's research shows that many who stumble are impatient, impulsive, manipulative, dominating, self- important, and critical of others. Moreover, Hagberg has concluded that the number of Rambos in pinstripes is increasing. Five years ago only half his CEO clients were classified as loners; today the figure is closer to 70%. He spoke with FORTUNE's Linda Grant.

Your studies have found that many CEOs don't have what it takes. What exactly is it about their leadership skills that's lacking?

We find there are three pillars of leadership: One is to be the inspirational evangelist for a vision. A lot of CEOs, we found, are mechanical and machine-like, and it's hard to be inspired by a problem-solving machine. Another pillar is to manage implementation--which many are good at--and a third is to build relationships with subordinates. We discovered that many CEOs are very egocentric. They don't think the third step is important, because the world doesn't exist beyond them. Therefore, they have a hard time developing talent. They are Rambo-like individualists who create a survival-of-the-fittest atmosphere.

How do these CEOs get their companies into trouble?

Under the stress and pressure that go with the job, many CEOs become reactive, listen less, and act impulsively without thinking. Their impatience drives them to focus on financial goals, which means they fail to build relationships with boards or their employees. One result is that people stop buying into their solutions. As a group, CEOs tend to be domineering and strong-willed; they state their opinions forcefully. As they distance themselves from others, it becomes harder for people to disagree with them. When that happens, they stop getting bad news or the benefit of a give-and-take conversation.

Why does that matter?

Teamwork, which you need in any corporation, suffers. When CEOs disconnect emotionally--which, by the way, may be a personal survival technique--they end up making decisions in a vacuum because they are alienated from others. Good leaders are demanding, but they maintain a connection to their people and therefore build a sense of loyalty. It's hard to be loyal to a machine.

Why do so many become alienated?

As a group, CEOs tend to be very independent and have high needs for autonomy. The more entrepreneurial they are, the stronger their need is to be in control. But many are poor communicators. They are good at developing a vision, and they think they have communicated it, but frequently their strategy isn't widely understood. As a result these leaders get confused and frustrated, because their people aren't doing what they think they've told them to do. They become critical of others and suspicious. This creates more barriers.

Many are also hobbled by self-importance, which keeps them from hearing feedback and prevents them from being objective about their own strengths and weaknesses. The head of one large company recently told me about an incident that occurred as he and his wife waited in line to get his driver's license renewed. He was frustrated at how long it was taking and grumbled to his wife, "I have a lot to do. Don't they know who I am?" She replied, "Yeah, you're a plumber's son who got lucky." Her remark really got to him. It drove home how far he had gotten caught up in his sense of self-importance.

How do they get to the top?

They produce financial results over the short run. A lot of companies reward independent cowboys who are not in it for the long haul. I see this in Silicon Valley, where the rate of change in high-tech companies is so fast and people often get promoted because of their technical skills. Great companies like Hewlett-Packard realize they have a lot of technical people, so they need to create a culture that reinforces management by walking around. HP, for example, uses open cubicles so people can't isolate themselves in offices, and spends a ton of money on training and development. It's almost a recognition that if they let automatic pilot take over, all those engineers won't communicate.

Are these CEOs capable of change?

Some are, if they get good feedback. But who's going to tell the emperor he has no clothes? It can limit your career. I think a lot of times consultants get hired because somebody thinks that a message needs to be delivered. But CEOs didn't get where they are by being stupid. If given credible feedback, they frequently run with it. But if they are too self-important, they will be defensive because they have a vested interest in maintaining an image of themselves as omnipotent. And that can be an absolute killer.