I have written a number of posts in the past on the so-called Dunning-Kruger Effect and its opposite, the Impostor Syndrome (see "Aristotle's Golden Mean", "Juste Milieu", "The July Effect and the Beginner's Bubble Hypothesis", "The Ignorance of Arrogance", and "Success is a Lousy Teacher"). I was very surprised to learn recently what inspired David Dunning and Justin Kruger to begin their research on the effect that now bears both of their names. To be honest, I've heard the story before, but certainly not in connection with the Dunning-Kruger Effect.
Several years ago, on January 6, 1995 to be exact, two men named MacArthur Wheeler (no relation) and Clifton Earl Johnson robbed two banks in the Pittsburgh area at gunpoint without attempting to disguise themselves - at least that's how it initially appeared. Neither man wore a mask - instead, they had applied lemon juice to their faces! Remember, lemon juice is one of the main ingredients in at least one of the common household recipes for invisible ink. Lemon juice apparently contains compounds that are colorless at room temperature. When you hold up a piece of paper with invisible ink on it next to a light bulb, the heat from the light bulb releases the carbon from these compounds, and exposure to the air oxidizes the carbon, causing the writing to magically appear.
According to Wheeler (again, no relation!), Johnson had told him that the lemon juice would make their faces invisible to the security cameras. Wheeler was initially skeptical - because who wouldn't be!?!?! However, he tested Johnson's recommendation by covering his face with lemon juice and taking a picture of himself with a Polaroid camera. Surprisingly, his face was missing from the resulting photograph (detectives later suggested that there had been a problem with the film, the camera, or Wheeler's photography skills).
The two bank robbers made off with over US$5,000, but were apprehended less than a week later following an anonymous tip in response to the release of the security camera footage of the two men on Pittsburgh Crime Stoppers. When shown the footage, Wheeler responded with surprise, "But I wore the lemon juice. I wore the lemon juice." Johnson pleaded guilty and testified against Wheeler ("Prisoner's Dilemma" anyone?) and was sentenced to five years in prison. Wheeler was convicted and sentenced to 24 1/2 years in prison.
David Dunning, a professor of social psychology at Cornell University read an account of the two bank robbers and reportedly said, "If Wheeler was too stupid to be a bank robber, perhaps he was also too stupid to know that he was too stupid to be a bank robber - that is, his stupidity protected him from an awareness of his own stupidity." He designed a study with his graduate student at the time, Justin Kruger, to determine how an individual's self-competence measured against to their actual level of competence. They published their findings in a 1999 paper, "Unskilled and unaware of it: How difficulties in recognizing one's own incompetence lead to inflated self-assessments". There findings subsequently led to the concept of the Dunning-Kruger Effect, in which our incompetence prevents us from recognizing our own lack of incompetence. As Dunning and Kruger wrote, "When people are incompetent in the strategies they adopt to achieve success and satisfaction, they suffer a dual burden: Not only do they reach erroneous conclusions and make unfortunate choices, but their incompetence robs them of the ability to realize it. Instead, like Mr. Wheeler, they are left with the mistaken impression that they are doing just fine."
Great backstory and analysis!
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