Analyses of the subjects’ ratings revealed three varieties of stupid mistakes. The first is when a person’s confidence outstrips their skill, as when a Pittsburgh man robbed two banks in broad daylight without wearing a disguise, believing that lemon juice he had rubbed on his face would make him invisible to security cameras. Or, in what is widely regarded as one of the top mascot failures in history, when Wild Wing of the Anaheim Ducks caught himself on fire attempting to leap over a burning wall (cheerleaders pulled him from the flames and he returned to action later in the game, unhurt). “This story of Duck a l’Orange County is no canard. A duck could get fired for this, or at least demoted to the Rotisserie League,” the New York Times reported.

The confidence-skill disconnect has been dubbed the Dunning-Kruger effect, after a study by social psychologists David Dunning and Justin Kruger. Dunning and Kruger had Cornell undergraduates perform tests of humor, logic, and grammar, and then rate how well they think they performed compared to other subjects in the study. The worst performing subjects, whose scores put them in the 12th percentile, estimated that they had performed in the 62nd percentile. Summarizing the findings, Dunning noted, “Poor performers—and we are all poor performers at some things—fail to see the flaws in their thinking or the answers they lack.” When we think we are at our best is sometimes when we are at our objective worst.

As any number of political scandals illustrate, the second type of stupid mistake involves impulsive acts—when our behavior seems out of control.