In an experiment he called "the cookie monster" study, Dacher Keltner, professor of psychology at University of California, Berkeley, and author of The Power Paradox: How We Gain and Lose Influence, brought groups of three people into a lab and randomly assigned one person a position of leadership. He then gave the group a writing task. After a half-hour of work, Keltner placed a plate of four freshly baked cookies in front of the team—one for each team member with one left over. In all groups, each person took one. Who would take the last remaining cookie? In nearly all cases, it was the person who'd been named the leader of the group who took the last cookie for themselves.

"In addition," Keltner writes in the Harvard Business Review, "the leaders were more likely to eat with their mouths open, lips smacking, and crumbs falling onto their clothes."

Such an experiment illustrates what Keltner calls "the power paradox." While people often gain power through behavior that advances the interests of others, such as empathy and collaboration, once they begin to feel powerful, those are the very qualities that diminish. Leaders then become more likely to engage in rude, selfish, and unethical behavior. In short, the old saying is true: Power does corrupt.

There's a neurological explanation at work. Sukhvinder Obhi, a neuroscientist at McMaster University in Ontario, put the brains of the powerful and the not-so-powerful under a transcranial-magnetic-stimulation machine, a device with an electromagnetic coil that that uses magnetic fields to stimulate nerve cells in the brain. What he found was that power impairs a specific neural process called "mirroring." In neural mirroring, a neuron fires both when we perform an action, like laughing or raising our hand in a meeting, and when we observe the same action performed by another. Researchers say this kind of vicarious experience may be a cornerstone of empathy.

But not only does neural mirroring, an unconscious response, decrease in the powerful, so too does psychological mimicking, the empathic response to laugh when others laugh, for example, that allows us to momentarily have an understanding of another person's experience. Powerful people "stop simulating the experience of others," Keltner told the Atlantic, which leads to what he calls an "empathy deficit."

It's not just power in the workplace, however. Other forms of privilege and entitlement, such as wealth can have a similar effect. In another experiment, for example, Keltner and a colleague found that drivers of the least expensive cars always ceded the right-of-way to pedestrians in a crosswalk. People driving luxury cars such as BMWs and Mercedes yielded only 54% of the time; nearly half the time they ignored the pedestrian and the law.

Power also heightens feelings of egocentricity. In another study, participants were asked to draw a capital E on their forehead with a washable marker. Those with power tended to draw the E on their forehead oriented to their own point of view, but which would appear reversed from the point of someone standing opposite them. Lack of empathy, coupled with egocentrism, aids and abets those in power to see people as means to an end, objects along their personal path to success.

"[Power] creates psychological distance between the powerful person and everything else," Batia Wiesenfeld, a management professor at New York University's Stern School of Business, told Fast Company.

"Here's the thing," wrote David Rock and Mary Slaughter of the NeuroLeadership Institute in Fast Company. "A lot of leaders fall into the trap of being stuck in the big picture, as well as the outcome. This can lead them to make ethically dubious decisions without thinking about the consequences. Similarly, this type of thinking can also present problematic business risks." To say nothing of your team turning on you.

So what's a powerful leader to do? Keltner says it comes down to awareness and actions of empathy, gratitude, and generosity.

The practice: Awareness

Awareness at work, and examination of one's demeanor at the office, is no different than a mindfulness practice at home: sit quietly, breathe deeply, quiet your mind. Practice what Buddhist teacher, Tara Brach, calls RAIN: Recognize, Allow, Interrogate, Non-Attachment.

The proof: Studies show that spending just a few minutes a day on such exercises gives people greater focus and calm; it's why these techniques are taught in training programs at companies like Google, Facebook, Aetna, General Mills, Ford, and Goldman Sachs, Keltner notes.

The practice: Empathy

Practice empathy in the workplace by thinking before a meeting about the individuals who will be present and what's going on in their lives. Is someone in the midst of a move or did they just drop their kid off for the first day of kindergarten that morning? Listen actively with attentive body language and vocal engagement (no looking at your phone during meetings). Ask questions and paraphrase the important points you hear. When employees come to you with difficult situations, take a moment to sympathize with them before launching into problem-solving mode. "That's really tough," and "I'm sorry" mean a lot.

The proof: Keltner advises we look at the U.S. Senate. Research has shown senators who used empathetic facial expressions and tones of voice when speaking to the floor got more bills passed than those who used domineering, threatening gestures and tones in their speeches.

The practice: Gratitude

Practice gratitude by making thank you's a regular part of how you communicate with your team. It can be handwritten notes, emails, and public praise and acknowledgement. Don't be afraid to give a fist bump or high-five to celebrate success.

The proof: NBA players who physically display their appreciation—through head raps, bear hugs, and hip and chest bumps—inspire their teammates to play better and win nearly two more games per season, Keltner's research has shown.

The practice: Generosity

Practice generosity by spending one-on-one time with your subordinates. Buy them lunch. Delegate and share high-profile responsibilities to those who have earned it, offer generous praise, and share the spotlight by giving credit for success not to yourself, but to all members of the team who made a win possible.

The proof: Those who share with others in a group, by contributing new ideas or lending a helping hand on projects not their own, are viewed as more worthy of respect and influence and thus well-suited for leadership, studies show.

The takeaway

Think not just about practicing empathic and generous leadership, but exercising enlightened power.

"Enlightened leadership is... the domain of awareness where we experience values like truth, goodness, beauty, love and compassion, and also intuition, creativity, insight and focused attention," said Deepak Chopra.

Sounds like a great boss.