To investigate this phenomenon in the lab, Dunning and Kruger designed some clever experiments. In one study, they asked undergraduate students a series of questions about grammar, logic and jokes, and then asked each student to estimate his or her score overall, as well as their relative rank compared to the other students. Interestingly, students who scored the lowest in these cognitive tasks always overestimated how well they did – by a lot. Students who scored in the bottom quartile estimated that they had performed better than two-thirds of the other students!
This ‘illusion of confidence’ extends beyond the classroom and permeates everyday life. In a follow-up study, Dunning and Kruger left the lab and went to a gun range, where they quizzed gun hobbyists about gun safety. Similar to their previous findings, those who answered the fewest questions correctly wildly overestimated their knowledge about firearms. Outside of factual knowledge, though, the Dunning-Kruger effect can also be observed in people’s self-assessment of a myriad of other personal abilities. If you watch any talent show on television today, you will see the shock on the faces of contestants who don’t make it past auditions and are rejected by the judges. While it is almost comical to us, these people are genuinely unaware of how much they have been misled by their illusory superiority.
Sure, it’s typical for people to overestimate their abilities. One study found that 80 per cent of drivers rate themselves as above average – a statistical impossibility. And similar trends have been found when people rate their relative popularity and cognitive abilities. The problem is that when people are incompetent, not only do they reach wrong conclusions and make unfortunate choices but, also, they are robbed of the ability to realise their mistakes. In a semester-long study of college students, good students could better predict their performance on future exams given feedback about their scores and relative percentile. However, the poorest performers showed no recognition, despite clear and repeated feedback that they were doing badly. Instead of being confused, perplexed or thoughtful about their erroneous ways, incompetent people insist that their ways are correct. As Charles Darwin wrote in The Descent of Man (1871): ‘Ignorance more frequently begets confidence than does knowledge.’