For generations, it's been a fact of life at the U.S. Naval Academy: As many as 10 percent of the eager young men and women who arrive in Annapolis to begin their officer training quit before the year is over. Scores more drop out before their four years are done.

"He just wasn't meant for this place," officials would say, removing the student from their rosters. Or: "She didn't really want to be here."

But at a time when the armed forces are struggling to attract and keep talented young people, academy officials are no longer willing to view such defections as regrettable but inevitable. And to better understand why some students thrive in the rigorous military environment while others flee, officials have gone back and analyzed 14 years of midshipmen's scores on a popular but controversial "personality typing" test. And they've come up with some startling insights.

The good news: They say they can now predict which students -- whether "extroverts" or "introverts," "thinkers" or "feelers" -- are most likely to drop out.

The bad news: Some of those dropouts might have made great admirals.

Now, academy officials are making small adjustments in their once-rigid program to help students over personality challenges that once might have ended a brilliant military career before it started.

"You don't want to coddle them. This is the military environment they're going to see the rest of their lives," said Glenn Gottschalk, the academy's director of institutional research. "What we're saying now is, `Don't throw in the towel the first time they look like they don't conform.' "

Gottschalk acknowledges that "plebe summer" -- the seven-week boot camp-style initiation marked by constant yelling from drill instructors and endless group marches -- seems to be particularly trying for students who by nature are quiet and introspective. They drop out in disproportionate numbers. Yet those very traits are highly valued by the Navy on submarines or in intelligence work.

Take Matt Vernon's plebe-year hallmate, for example. He wanted to be a submariner, and he probably would have done well in that confined, stressful environment, judging by the amount of time he spent in his room studying and working on his computer. Yet his seeming passivity didn't play well with his superiors.

"He would always volunteer to take people's duties, but he did it in a low-key way so he wasn't getting the credit," said Vernon, 24, an extroverted senior from Las Vegas. Frustrated by his mediocre grades on military performance reviews, Vernon's friend dropped out near the start of his sophomore year.

Such are the casualties at a school where "sink or swim" could be the motto and spit-polish perfection is the goal. Even when the plebe summer initiation period ends, midshipmen find themselves in a college environment alien to any civilian student -- mandatory meals, evenings scrubbing the bathroom, weekends confined to campus.

"To get through here, you need a strong personality and a good sense of humor," said Christy Kercheval, an 18-year-old plebe from Houston, who said she has had to rein in some of her natural exuberance since coming to Annapolis. "This is not a normal life."

Character and personality have always been scrutinized and debated at the Naval Academy, which traditionally has valued such traits as self-confidence, risk-taking, derring-do and fierce loyalty. The hallmarks of Navy heroes, such characteristics also were found in the midshipmen whose cheating and carousing brought scandal upon the school in the mid-'90s.

An oft-cited example of this paradox is Sen. John McCain (R-Ariz.), now running for president. During the Vietnam War, he was the tenacious jet pilot who withstood six years of torture and isolation in a prison camp. At the Naval Academy, he was the rules-breaking party animal who graduated near the bottom of his class.

Now, with this deeper scrutiny of personality types, the academy is undergoing what one observer calls a "behavioral science revolution." A new masters program for the young officers who supervise midshipmen is steeped in studies of human behavior and interpersonal dynamics. And a freshman-year leadership class that once focused on management techniques and inspiring tales of Navy daring was revamped this year with a strong infusion of psychology.

The goal is self-awareness but also a heightened sensitivity toward others. "If you don't know your people, you can't be a leader," said Lt. Douglas Marlow, a clinical psychologist who teaches the class.

It is in this class that freshmen first discuss their results on the famous Myers-Briggs Type Indicator test. Designed by a mother-daughter team of psychologists more than 50 years ago, the test draws on the tenets of Carl Jung, a Swiss psychiatrist and psychologist, to categorize people based on how they interact with others, process information and make decisions.

Typical questions include "Are you easy to get to know, or hard to get to know?" and "Do you cherish faith in things that cannot be proved, or believe only those things that can be proved?" The results then purport to show whether the taker is an extrovert or introvert, sensory or intuitive, a thinker or feeler, and a judger or perceiver.

While scorned by many psychologists, the test has gained tremendous popularity in management and counseling circles. The academy's analysis of its test results, given to freshmen during their first week, shows that the military college environment may be friendlier to one type of student than another.

For example, most midshipmen are Sensory-Thinking-Judgmental types who thrive on the discipline and order. They're often considered the born administrators and leaders, sometimes referred to as the guardian or duty fulfiller types.

They make up only about 15 percent of the general population but account for 33 percent of the people who choose to enter the Naval Academy. Yet they make up only about 15 percent of the voluntary dropouts.

In contrast, Feeling-Perceptive types -- creative, empathetic -- make up about 35 percent of the general population but only about 17 percent of the brigade. But chafing under the regimentation and dispirited by the constant criticism, they make up about 30 percent of the dropouts.

"They leave in plebe summer," Gottschalk said. "For them, it's `What do you mean I have to stand at attention? What do you mean I have to cut off my beard?' "

Introverts, meanwhile, make up only about 33 percent of the brigade but more than 55 percent of the voluntary dropouts.

Paul Roush, a retired Marine colonel and former leadership and ethics professor at the academy, said that studies of test results from the Pentagon's war colleges show that fewer than 20 percent of admirals and generals are personality types other than the forceful thinker-judgers.

"But that's probably not for the best," Roush said. "You're probably better off having some other types as well" in upper leadership.

Gottschalk also believes Myers-Briggs results may shed some light on women's low application and high attrition rates. Women make up only about 18 percent of the student body, and about 17 percent drop out.

He notes that while most women are Feeling-Perceivers, those who choose to come to the Naval Academy are mostly Sensing-Thinking-Judgers -- just like the guys. The typical Naval Academy man, he theorizes, is baffled by these intense, competitive women.

"He sees the women here and says, `She isn't like my mother, she isn't like my sister.' He either treats her as one of the guys, or he treats her like some kind of freak."

In the Myers-Briggs worldview, there is no right or wrong type. Every type has its strength: Feelers are empathetic and considerate, perceivers are adaptable and able to make quick decisions. Academy officials insist that every type has a place at Annapolis. So they are taking small steps to accommodate and encourage students of the various personality types, in hopes of reducing the dropout rate.

Athletic coaches are being taught about the personality types and are being encouraged to match plebe team members with upper-class mentors of a similar personality type. Starting next year, all company officers will be told their midshipmen's Myers-Briggs classifications. Academy officials may even alert them to the "at-risk" personality types and urge them to reach out to those students.

Yet Daniel Druckman, a psychologist and professor of conflict resolution at George Mason University who has studied the use of Myers-Briggs, cautions that it would be "dangerous" to base administrative decisions on results of the tests, which he says force test-takers to pick extremes that may not fit their actual preferences.

"We're being stereotyped," he said. "It can become a kind of self-fulfilling prophecy." Many social scientists are highly skeptical of the Myers-Briggs test, saying there is little peer research to confirm its findings.

Indeed, the academy community -- many of them Extrovert-Sensing-Thinking-Judgers, Gottschalk notes, and typically averse to "touchy-feely" stuff -- may be reluctant to fully embrace the quasi-science.

Lt. Monica Mitchell, an officer who supervises a company of about 140 midshipmen, analyzed Myers-Briggs data for her master's degree last year but would rather not know her students' categories. "I don't want to prejudice my interactions with them," she said.

Gottschalk and other academy officials emphasize that they are moving slowly with personality typing. They say it will never be a consideration in admissions or promotion decisions -- there is no personality type, they say, that does not belong at the academy.

Company officer Lt. Philip E. Kapusta has on file the Myers-Briggs ratings of all 138 midshipmen he supervises. He was surprised to realize that the top-ranking freshman in his company is an Introverted-Sensing-Feeling-Perceptor -- the quiet, sensitive type that often drops out.

"You have to broach this carefully," Kapusta said. "You don't want to tell people, `You're doomed to fail.' "