The Dunning-Kruger effect occurs when incompetent people not only fail to realise their incompetence, but consider themselves much more competent than everyone else. Basically – they’re too stupid to know that they’re stupid.
If you have no doubts whatsoever about your brilliance, you could just be that damn good. On the other hand…
The Dunning-Kruger effect is a slightly more specific case of the bias known as illusory superiority, where people tend to overestimate their good points compared to others. The effect has been shown by experiment in several ways. Dunning and Kruger tested students on a series of criteria such as humour, grammar, and logic and compared the actual test results with each student’s estimations of their performance. Those who scored lowest on the test, in the bottom quartile, were found to have “grossly overestimated” their scores. Conversely, those with the highest scores underestimated their performance in comparison to others.
The tendency for those who scored well to underestimate their performance was explained as a form of psychological projection: those who found the tasks easy (and thus scored highly) mistakenly thought that they would also be easy for others. This is similar to “impostor syndrome” — found notably in graduate students and high achieving women — whereby high achievers fail to recognise their talents as they think that others must be equally good.
And what about the underachievers who overestimated their performance? In the words of Dunning and Kruger, “this overestimation occurs, in part, because people who are unskilled in these domains suffer a dual burden: Not only do these people reach erroneous conclusions and make unfortunate choices, but their incompetence robs them of the metacognitive ability to realize it.”
The effect can also be summarised by the phrase “a little knowledge is a dangerous thing”. A small amount of knowledge can mislead a person into thinking that they’re an expert because this small amount of knowledge isn’t a well known fact. For a potent example, consider former children’s TV presenter and science advocate Johnny Ball, who in 2009 stunned audiences by denying the existence of climate change. His reasoning was based on the fact that water vapour as a greenhouse gas is much more prevalent and thus much more powerful than carbon dioxide — and because combustion reactions also produce water, it should be water we’re worried about, not carbon dioxide. Sound reasoning to an amateur, but anyone minimally qualified in atmospheric chemistry would tell you that the water isn’t a problem because the atmosphere has a way of getting rid of excess water — it’s called “rain”. Thus its concentration (for given temperatures and pressures) remains more or less constant globally.
In a nutshell.
The effect is named after the valiant scientists who properly proved its existence in their seminal, 2000 Ig Nobel Prize winning paper Unskilled and Unaware of It, doubtless at great risk to personal sanity.
The idea that people who don’t know enough also don’t know enough to realise that they don’t know enough (“Dunning-Kruger effect” is so much simpler to get your tongue around) isn’t particularly new. Bertrand Russell in The Triumph of Stupidity in the mid 1930s said that “The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” Even earlier, Charles Darwin, in The Descent of Man in 1871, stated “ignorance more frequently begets confidence than does knowledge”. Following a 2008 study by Helmuth Nyborg, which showed a slight but significant negative correlation between religiosity and IQ, Nyborg theorised that this is because “…people with a high intelligence are more skeptical” – in other words, those with higher intelligence will also be more doubting about their ability to be right, because they possess the cognitive ability to gauge themselves better.