Dunning–Kruger effect

The Dunning–Kruger effect is a cognitive bias in which low-ability individuals suffer from illusory superiority, mistakenly assessing their ability as much higher than it really is. Psychologists David Dunning and Justin Kruger attributed this bias to a metacognitive incapacity, on the part of those with low ability, to recognize their ineptitude and evaluate their competence accurately. Their research also suggests corollaries: high-ability individuals may underestimate their relative competence and may erroneously assume that tasks which are easy for them are also easy for others.

Dunning and Kruger have postulated that the effect is the result of internal illusion in those of low ability and external misperception in those of high ability: "The miscalibration of the incompetent stems from an error about the self, whereas the miscalibration of the highly competent stems from an error about others."

The phenomenon was first observed in a series of experiments by Dunning and Kruger of the department of psychology at Cornell University in 1999. The study was inspired by the case of McArthur Wheeler, a man who robbed two banks after covering his face with lemon juice in the mistaken belief that, because lemon juice is usable as invisible ink, it would prevent his face from being recorded on surveillance cameras. The authors noted that earlier studies suggested that ignorance of standards of performance lies behind a great deal of incorrect self-assessment of competence.

This pattern of over-estimating competence was seen in studies of skills as diverse as reading comprehension, practicing medicine, operating a motor vehicle, and playing games such as chess or tennis. Dunning and Kruger proposed that, for a given skill, incompetent people will:

Dunning has since drawn an analogy – "the anosognosia of everyday life" – with a condition in which a person who experiences a physical disability because of brain injury seems unaware of, or denies the existence of, the disability, even for dramatic impairments such as blindness or paralysis: "If you're incompetent, you can't know you’re incompetent.… [T]he skills you need to produce a right answer are exactly the skills you need to recognize what a right answer is."

...
Wikipedia