In the interest of promoting democracy, President Musharraf of Pakistan recently announced that he had to lock up most of his country’s democracy activists. And because he wanted the Pakistani Supreme Court to independently rule on whether he could continue as president, General Musharraf also locked up the country’s top judges and replaced them with yes men.

Seen in the long light of history, last week’s court ruling that General Musharraf could continue in power was less Machiavellian than unoriginal. For as far back as historical records go, people in power have told astonishingly bald-faced lies, saying they are acting in the public interest when they are really acting in their own.

Saddam Hussein won “elections” with upwards of 95% of the vote — the missing 5%, no doubt, being a dictator’s gesture in the direction of modesty. In earlier times, conquests and colonialism, even slavery, have been justified as being in the best interest of the victims.

The standard explanation for why those in power act in self-interested, venal, and authoritarian ways is that they are bad apples to begin with. Indeed, many people believe that such men and women are the ones most likely to rise to power. But new research in political science and psychology has provided a novel explanation for why leaders and managers regularly let their followers down and resort to the kind of “layoffs and pay cuts are good for you” talk that defines absurdity. These studies show that leaders often emerge from communities not because they are ruthless, but because they are skilled at managing social relationships.

Something happens to people once they acquire power, however, and the transformation appears to be psychological. Adam Galinsky, a social psychologist at Northwestern University’s Kellogg School of Management, recently had volunteers describe either a situation in which they had power over someone else or a situation in which they felt powerless. Those asked to remember a situation in which they felt powerful were made to feel even more powerful by being given control of the distribution of goodies, whereas the volunteers asked to remember a powerless situation were further reminded of their powerlessness when they were asked to estimate how many goodies they expected to receive. When Mr. Galinsky and his colleagues asked all the volunteers to draw the letter “E” on their foreheads with a marker, those who had been made to feel powerless were three times more likely to draw the “E” so that it was legible to someone facing them. Those made to feel powerful, however, drew the letter so that it looked correct from their internal perspective but was a mirror image from the point of view of someone facing them. Mr. Galinsky’s point, which he noted in a study published in the journal Psychological Science, is that volunteers made to feel powerful, even in a trivial laboratory experiment, almost instantly lose the ability to see things from other people’s points of view. Dacher Keltner, a social psychologist at the University of California at Berkeley, said Mr. Galinsky’s finding reflects a growing realization that power entails a paradox. “People in organizations and in hierarchies and in informal groups like college dorms want leaders to be socially intelligent,” Mr. Keltner said. “They will sacrifice all manner of things to have leaders who are thoughtful and engaged and give other people voice.”

But once socially gifted people rise to power, Mr. Keltner added, the paradox is that “power simplifies our thinking. We tend to see things in terms of our own self-interest, and it makes us more impulsive. We forget our audience in service of gratifying our own impulses.”

Mr. Keltner and others have shown that power exacerbates many cognitive biases. People who lack power turn out to be more accurate in guessing the opinions of those around them, whereas those in power tend to be inaccurate. Because subordinates are also hesitant to tell superiors things they do not want to hear, the problem gets worse, with powerful people having even less input and perspective about how others think and feel. Even Supreme Court justices, a Stanford University psychologist, Deborah Gruenfeld, found, write more complex arguments when they are in the minority compared with when they are part of the majority.

In some ways, the results should not be surprising: Not having power forces you to see things from other people’s points of view and increases empathy and social behavior. Having power allows you to ignore other points of view — depriving you of the social skills that led to power in the first place. When powerful people such as General Musharraf say and do things that are absurd, in other words, it could be that they are simply unaware of how they appear to others.

Mr. Keltner once had groups of three people sit before a bowl that contained five cookies, and each volunteer took one. That left two cookies. By mutual agreement, the volunteers always left the last cookie in the bowl. So who took the fourth cookie? Invariably, Mr. Keltner found, the person in the group who had been randomly assigned to feel powerful grabbed the fourth cookie. “We videotaped how they ate,” Mr. Keltner said. “The high-powered person ate with their mouth open, cookie crumbs falling all over their shirt.”