I call this phenomenon “the power paradox,” and I’ve studied it in numerous settings: colleges, the U.S. Senate, pro sports teams, and a variety of other professional workplaces. In each I’ve observed that people rise on the basis of their good qualities, but their behavior grows increasingly worse as they move up the ladder. This shift can happen surprisingly quickly. In one of my experiments, known as “the cookie monster” study, I brought people into a lab in groups of three, randomly assigned one to a position of leadership, and then gave them a group writing task. A half hour into their work, I placed a plate of freshly baked cookies—one for each team member, plus an extra—in front of everyone. In all groups each person took one and, out of politeness, left the extra cookie. The question was: Who would take a second treat, knowing that it would deprive others of the same? It was nearly always the person who’d been named the leader. In addition, the leaders were more likely to eat with their mouths open, lips smacking, and crumbs falling onto their clothes.