(FORTUNE Small Business) – Before we explore the world of psychological tests--how they can plumb the depths of your psyche and tone your managerial muscle--let's note a simple fact. Experts' shorthand for these tests is a "battery," as in "brutal," not "AA." For example, here are test results that Allan Harris, chief executive officer of Harris McCully Associates, an executive coaching firm in New York City, has occasionally delivered to top executives: You're a screamer and yeller. You're moody. You're strangling your employees with micromanagement.

So maybe you don't want to torture yourself with insults that you've actually had to pay for. Right? After all, testing your mind and managerial mettle can seem like a lot of expensive hocus-pocus. And frankly, many business owners couldn't care less about being a better boss when they're racking their brains over more compelling concerns, like meeting payroll. But testing for skills and aptitudes has been widely used ever since World War I, when the Army began measuring recruits' intelligence in order to select candidates for officer training. In recent years CEOs and top executives have begun to appreciate the way that such assessment tests can diagnose their own managerial weaknesses.

So what can they do for your company? Fix you--the biggest source of small-company problems. For example: "Most CEOs of entrepreneurial companies have difficulty delegating," says Harris. That can destroy revenue, thereby killing growth. Business owners are also frequently inept at developing employees' talents and hiring managers whose skills complement their own.

Profiting from an assessment test requires two steps and one leap of faith. The first step is taking a test to understand your aptitudes and behaviors. "One of the major issues in becoming a better leader is saying, 'I am aware of who I am and of the impact I have on others,' " says Gloria Henn of Henn & Green Associates, an executive coaching firm in Williston Park, N.Y. The second step is changing ineffective behavior. The leap of faith? Trusting that your self-enlightenment will ripple through your company, unleashing a torrent of benefits: greater efficiency, happier employees, and faster growth.

This sounded too squishy to be true. But then I talked to Ron Parks, a self-confessed assessment junkie who owns and runs Millard Manufacturing, a metal fabrication and machining company in Omaha with $10 million in sales. Frustrated with internal communication snafus and poorly performing new hires, Parks began looking for ways to fix things. He began by first fixing himself and eventually took a series of classic personality assessments, such as the Myers-Briggs and Singer-Loomis tests.

The key lesson he learned: to appreciate the enormous differences between people. (Pretty squishy, eh?) "One of the biggest mistakes executives make is that they frame every answer the way they would like to hear an answer," he says. "They don't take into consideration the way a person can best absorb information." Telling a detail-oriented subordinate that a report needs to be "customer friendly" isn't helpful. What's more effective is asking the writer of the report to mention three ways in which customer revenues will grow.

Parks' test-taking regimen triggered an overhaul of his own management style and his company's development of new managers. He's learned to double-check and triple-check the meaning behind an employee's or a client's comments until he's satisfied that he fully understands them. He also uses formal testing and informal questions derived from aptitude tests to match employees' temperaments to jobs at Millard, which has led to lower turnover and improved skills. "Frankly, some people are not meant to manage other people. But in the business world we have made it the only way to progress," he says.

Parks says the most useful test he took was at the Johnson O'Connor Research Foundation, an aptitude-testing organization with 11 test centers across the country. Steve Greene, director of the foundation's New York center, says that successful managers own a distinctive set of aptitudes, including a strong vocabulary, a preference for the big picture rather than minutiae, and an ability to work well with and through others.

So how do you begin testing yourself? There is a daunting array of tests to choose from on the Web, in print, and at dozens of executive development firms. A better question: Do you simply want a little more insight into yourself--or do you want someone to teach you how to change? An entire industry has been built around putting CEOs and their companies on the couch, so it's no surprise that many experts insist that assessment tests are useless without an expensive coach to help you implement your transformation. But Caela Farren, an entrepreneur with a Ph.D. in organizational behavior, has built MasteryWorks, in Annandale, Va., around online and print self-assessment tests. Business people are perfectly capable of understanding test results and following recommendations for change, she says.

If you simply want to take a test and have the results interpreted, look for a Johnson O'Connor-style testing organization online or off by asking an organizational behavior professor at a nearby business school for some recommendations. If you want an expert to shepherd you through the test and coach you on becoming the next Lou Gerstner, seek an endorsement from another business owner or a trade organization. Making the most of an assessment test may mean that you'll have to stop screaming and yelling and micromanaging your employees. But don't worry. You'll find more important things you can do for your company.