First there was Bill Cosby’s sexual harassment charges, then the Uber Crisis and CEO Travis Kalanick’s resignation amid an investor revolt and just last month, movie mogul  Harvey Weinstein was ousted from Miramax by his own board of directors in light of dozens of sexual harassment allegations. Some of these behaviours have persisted for years, some for several decades.

But the public shouldn’t have been so shocked. From corruption allegations, to prostitution scandals to charges against corporate executives and world-class athletes, on any given day, the headlines read of the latest misstep of someone in a position of power.

Surveys of organizations find that the vast majority these vulgarities, indecorum  and indecent  behaviors have their roots in the offices of those with the most authority.

Psychologists refer to this as the Paradox of Power

Once they rise to power, the very traits that helped leaders accumulate control in the first place all but disappear. Instead of being honest, outgoing and polite, they become negligent, imprudent, reckless and heedless.

While some may believe that these characteristics are beneficial to success, they can ultimately prove to be counter-productive. In direct contrast, instead of gaining clarity, becoming more decisive and developing resolute to make choices that will be profitable,  regardless of their popularity, they start down the path of self-annihilation.

One study found that overconfident CEOs were more likely to pursue innovation and take their companies to new heights. Unchecked, however, these instincts can lead to a miserable demise.

But first, the good news

A few years ago, Dacher Keltner, a psychologist at the University of California, Berkeley, began interviewing freshmen at a large dorm on the Berkeley campus. He gave them free pizza and a survey, which asked them to provide their first impressions of every other student in the dorm. Mr. Keltner returned at the end of the school year with the same survey and more free pizza. According to the survey, the students at the top of the social hierarchy—they were the most “powerful” and respected—were also the most considerate and outgoing, and scored highest on measures of agreeableness and extroversion. In other words, the nice guys finished first.

This result isn’t unique to Berkeley undergrads. Other studies have found similar results in the military, corporations and politics. “People give authority to people that they genuinely like,” says Mr. Keltner.

Of course, these scientific findings contradict the cliché of power, which is that the only way to rise to the top is to engage in self-serving and morally dubious behavior. The 16th century Italian philosopher Niccolo Machiavelli insisted that if a leader has to choose between being feared or being loved, Machiavelli insisted that the leader should always go with fear. Love is overrated.

That may not be the best advice. A group of sorority sisters were recruited to spread malicious gossip. It turned out that the Machiavellian sorority members were quickly identified by the group and isolated. Nobody liked them, and so they never became powerful.

It’s reassuring to think that the surest way to accumulate power is to do unto others as you would have them do unto you.

In recent years, this theme has even been extended to non-human primates, such as chimpanzees. Frans de Waal, a primatologist at Emory University, observed that the ability to forge social connections and engage in “diplomacy” is often much more important.

Now for the bad news

What happens when all those nice guys actually get in power? This is where “nice guys” morph into a very different kind of beast.

“It’s an incredibly consistent effect,” Mr. Keltner says. “When you give people power, they basically start acting like fools. They flirt inappropriately, tease in a hostile fashion, and become totally impulsive.”

Mr. Keltner compares the feeling of power to brain damage, noting that people with lots of authority tend to behave like neurological patients with a damaged orbito-frontal lobe, a brain area that’s crucial for empathy and decision-making. Even the most virtuous people can be undone by the corner office.

Why does power lead people to flirt with interns and solicit bribes and fudge financial documents?

According to psychologists, one of the main problems with authority is that it makes us less sympathetic to the concerns and emotions of others. For instance, several studies have found that people in positions of authority are more likely to rely on stereotypes and generalizations when judging other people. They also spend much less time making eye contact, at least when a person without power is talking.

Consider a recent study led by Adam Galinsky, a psychologist at Northwestern University. Mr. Galinsky and colleagues began by asking subjects to either describe an experience in which they had lots of power or a time when they felt utterly powerless.

Then the psychologists asked the subjects to draw the letter E on their foreheads. Those primed with feelings of power were much more likely to draw the letter backwards, at least when seen by another person.

Mr. Galinsky argues that this effect is triggered by the myopia of power, which makes it much harder to imagine the world from the perspective of someone else. We draw the letter backwards because we don’t care about the viewpoint of others.

At its worst, power can turn us into hypocrites. In a 2009 study, Mr. Galinsky asked subjects to think about either an experience of power or powerlessness. The students were then divided into two groups. The first group was told to rate, on a nine-point scale, the moral seriousness of misreporting travel expenses at work. The second group was asked to participate in a game of dice, in which the results of the dice determined the number of lottery tickets each student received. A higher roll led to more tickets.

Participants in the high-power group considered the misreporting of travel expenses to be a significantly worse offense. However, the game of dice produced a completely contradictory result. In this instance, people in the high-power group reported, on average, a statistically improbable result, with an average dice score that was 20% above that expected by random chance. (The powerless group, in contrast, reported only slightly elevated dice results.) This strongly suggests that they were lying about their actual scores, fudging the numbers to get a few extra tickets.

Although people almost always know the right thing to do—cheating is wrong—their sense of power makes it easier to rationalize away the ethical lapse.

For instance, when the psychologists asked the subjects (in both low- and high-power conditions) how they would judge an individual who drove too fast when late for an appointment, people in the high-power group consistently said it was worse when others committed those crimes than when they did themselves. In other words, the feeling of eminence led people to conclude that they had a good reason for speeding—they are the important  people, with important things to do—but that everyone else should follow the posted signs.

Like Mr. Keltner said: people with lots of authority tend to behave like neurological patients with a damaged orbito-frontal lobe – giving the statement “It’s all gone to his head” a whole new perspective.