Every working adult has known one - a boss who loves making subordinates squirm, whose moods radiate through the office, sending workers scurrying for cover, whose very voice causes stomach muscles to clench and pulses to quicken.

It is not long before dissatisfaction spreads, rivalries simmer, sycophants flourish. Normally self-confident professionals can dissolve into quivering bundles of neuroses.

"It got to where I was twitching, literally, on the way into work," said Carrie Clark, 52, a former teacher and school administrator in Sacramento, Calif., who said her boss of several years ago baited and insulted her for 10 months before she left the job. "I had to take care of my health."

Researchers have long been interested in the bullies of the playground, exploring what drives them and what effects they have on their victims. Only recently have investigators turned their attention to the bullies of the workplace.

Around the country, psychologists who study the dynamics of groups and organizations are discovering why cruel bosses thrive, how employees end up covering for managers they despise and under what conditions workers are most likely to confront and expose a bullying boss.

Next week, researchers and policy makers from many nations will convene in Bergen, Norway, to discuss the issue.

"What we're finding," said Dr. Calvin Morrill of the University of California at Irvine, who studies corporate culture, "is that some of the behaviors that we think most protect us are what in fact allow the behavior to continue. Workers become desensitized, tacitly complicit and don't always act rationally."

Bullying bosses, studies find, differ in significant ways from the Blutos of childhood. In the schoolyard, particularly among elementary school boys, bullies tend to pick on smaller or weaker children, often to assert control in an uncertain social environment in which they feel vulnerable.

But adult bullies in positions of power are already dominant, and they are just as likely to pick on a strong subordinate as a weak one, said Dr. Gary Namie, director of the Workplace Bullying and Trauma Institute, an advocacy group based in Bellingham, Wash. Women, Dr. Namie said, are at least as likely as men to be the aggressors, and they are more likely to be targets.

In leadership positions that require the exercise of sheer violent will - on the football field or the battlefield - this approach can be successful: Consider Vince Lombardi and George Patton. But in an office or on a factory floor, different rules apply, and bullying usually has more to do with the boss's desires than with the employees' needs.

A manager might use bullying to swat down a threatening subordinate, for example, said Dr. Harvey A. Hornstein, a retired professor from Teachers College at Columbia University and the author of "Brutal Bosses and Their Prey." Or a manager might be looking for a scapegoat to carry the department, or the supervisor's, frustrations.

But most often, Dr. Hornstein found, managers bullied subordinates for the sheer pleasure of exercising power.

"It was a kind of low-grade sadism, that was the most common reason," he said. "They'd start on one person and then move on to someone else."

The mystifying thing about this pattern is that it does not appear to undercut productivity. Workers may loathe a bullying boss and hate going to work each morning, but they still perform. Researchers find little relationship between people's attitudes toward their jobs and their productivity, as measured by the output and even the quality of their work. Even in the most hostile work environment, conscientious people keep doing the work they are paid for.

At the same time, some employees withhold the unpaid extras that help an organization, like being courteous to customers, helping co-workers with problems or speaking well of the company. Yet this falloff in helpfulness and, indirectly, in performance is smaller than might be expected, because fear motivates different people differently, said Dr. Bennett Tepper, an organizational psychologist at the business school of the University of North Carolina, Charlotte.

In April, he reported the results from a study of 173 randomly chosen employees in a wide range of work. He found that in situations where bosses were abusive, some employees did little or nothing extra, while others did a lot, partly covering for less helpful peers.

"This is not what we expected," Dr. Tepper said. "And we speculate that one reason people keep doing extra in these abusive situations is to advance themselves at the expense of others. It makes them look good and the others look that much worse."

So tyrants spread misery, and from the outside it looks as if they are doing a fine job. It does not help matters, psychologists say, that people who enjoy abusing power frequently also revere it and are quick to offer that reverence to the even-more-powerful. Bullying bosses are often experts at "managing up."

Subordinates know viscerally the high cost of going around a boss, even if it is simply to file a complaint with the human resources department. You are trouble. You are a whiner. You have called out the manager behind his back.

One reason management researchers do not know how effective it is to take on a cruel boss directly is because so few employees do it.

For many people, run-ins with a supervisor stirs up old conflicts with parents, siblings or other larger-than-life figures from childhood. Dr. Mark Levey, a psychotherapist in Chicago who consults with corporations, said that nasty bosses often elicited from subordinates defensive habits that they first developed as children, like reflexive submission and explosive rage.

"Once these defensive positions lock in,'' Dr. Levey said, "it's like people are transported to a different reality and can no longer see what's actually happening to them and cannot adapt."

Emelise Aleandri, an actress and a producer in her 50's who lives in New York, said she was forced out of a producing position by a bullying boss, who replaced her with an underling.

"Some people were afraid to do anything,'' Ms. Aleandri said. "But others didn't mind what was happening at all, because they wanted my job."

Ambition, experts say, is the bully's most insidious deputy. Dr. Leigh Thompson, an organizational psychologist at Northwestern University, and Cameron P. Anderson, of the New York University business school, are studying the effects of varying management styles on the behavior of small groups.

In one simulation, business students gather in teams of three, acting out the parts of company managers meeting to divvy up resources. The students are randomly assigned to one of three roles, the top manager of a large company, a middle manager and a lower-ranking manager.

After the negotiations begin, the researchers find, the heavyweights quickly dominate and, with regular meetings, they also transform the behavior of the No. 2 managers.

"If the person in charge is high energy, aggressive, mean, the classic bully type,'' Dr. Thompson said, "then over time, that's the way the No. 2 person begins to act."

She added that this holds true no matter how low-key and compassionate the No. 2 person looks on personality tests outside the simulation. Working to please and impress a more powerful figure, the second-tier managers are temporarily transformed into carbon copies of the alpha dogs, and in the simulation, they tend to corner the money and cut out the lowest-level players.

It works the other way, as well. A top manager with a gentler nature softens the edges of more aggressive midlevel managers, Dr. Thompson said. The third player is entirely at the mercy of this dynamic.

In another study, Dr. Michelle Duffy, a psychologist in the University of Kentucky business school, is following 177 hospital workers. At the beginning of the study, the employees answered detailed questions about their work and relationships with managers. They also took a test of moral disengagement, a measure of people's sensitivity to others, for example, their views on the appropriateness of jokes, put-downs and coldness toward colleagues.

Six months later, the workers took the same test again. Those who worked for bosses they found intimidating had become less sensitive, according to a preliminary reading of the responses. Those who worked for managers whom they perceived as supportive or fair, Dr. Duffy said, scored the same or better.

"It looks like if there's a strong leader in the group, then that person's behavior is contagious," she said. And if that leader is nasty, "this moral disengagement spreads like a germ."

Psychologists who study obedience say subordinate status itself causes people to defer to a supervisor's judgment, especially in well-defined hierarchies. It's the boss's job to make decisions, after all, and co-workers may think there is some legitimate hidden reason for the boss's behavior.

Selfishly, too, workers who witness a boss humiliating a colleague are relieved that the sword has fallen elsewhere and are secretly pleased that they look more competent by comparison. In earlier work that involved interviews with 500 employees in Europe and the United States, Dr. Duffy found that workers were delighted to receive praise from a boss, but even more delighted when the praise was accompanied by news that another colleague is struggling.

This occupational schadenfreude is evident when employees observe a co-worker being bullied. After watching in silence, they then begin to resolve their guilt.

"They do this by wondering whether maybe the person deserved the treatment, that he or she has been annoying, or lazy, they did something to earn it," Dr. Duffy said.

The brutal behavior goes unchallenged, and the target feels a sudden chill of isolation that is all too real. By doing nothing, even people who abhor the bullying become complicit in the behavior and find themselves supplying reasons to justify it.

"The people in my office eventually started blaming me," said Sherry Hamby, 42, of Tulsa, Okla., an advocate of family mental health who said she was fired after repeated verbal abuse from a boss. "This was a man who insulted me, who insulted my family, who would lay into me while everyone else in the office just sat there and let it happen."

The most common form of resistance to a cruel manager remains the old-fashioned grousing session. Sharing the misery over lunch or a drink can makes everyone feel a little better and signal the first step in jointly responding to the abuse. Sociologists who study dissent within large organizations like factories and hospitals find that informal kvetching sessions may evolve into effective resistance when workers are united, well connected with others in the organization and trust the company's higher-ups to hear their case.

More often, though, grousing simply feeds on itself, sometimes devolving into elaborate self-contained gatherings in which the central activity is bad-mouthing and mimicking the boss, said Dr. Morrill of the University of California.

He and Dr. Corinne Bendersky, an associate professor at the University of California, Los Angeles, are studying 150 M.B.A.'s in human resources departments to determine which kinds of employees are most likely to file complaints against abusive bosses and under which circumstances.

"We hypothesize, based on a preliminary read of our data, that employees in tight-knit informal groups may ironically be less likely to think about confronting their bosses," Dr. Morrill wrote in an e-mail message. "Instead, they may retreat to their informal groups to let off steam."

It is those who are not part of a tight group, who feel truly desperate and in danger of losing their jobs, who appear most likely to speak up, he said. Most others learn to perform an elaborate dance, trying to preserve their status while being careful not to forfeit their sense of decency, all the while looking for an escape hatch.

One of the best strategies to manage a bully, Dr. Hornstein of Columbia has found in his research, is to watch for patterns in the tyrant's behavior. Maybe he is bad on Mondays, maybe a little better on Fridays. Maybe she is kinder before lunch than after. If the Mets lost the day before, it is not a good day to ask for anything. If some types of assignments spook the person more than others, avoid them, if possible.

When the nostrils quiver and the lip tightens, Dr. Hornstein said, all is not lost. Ignore the insulting tone of a boss's attack, he said, and respond only to the substance of the complaint. If it is a deadline problem, address that. For an attack on a particular skill, discuss ways to improve.

"Stick with the substance, not the process,'' he said, "and often it won't escalate."