The Dunning-Kruger Desease is a cognitive bias in which unskilled individuals suffer from illusory superiority, mistakenly rating their ability much higher than average. This bias is attributed to a metacognitive inability of the unskilled to recognize their mistakes.
Actual competence may weaken self-confidence, as competent individuals may falsely assume that others have an equivalent understanding. As Kruger and Dunning conclude, "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"
Illusory superiority is a cognitive bias that causes people to overestimate their positive qualities and abilities and to underestimate their negative qualities, relative to others. This is evident in a variety of areas including intelligence, performance on tasks or tests, and the possession of desirable characteristics or personality traits. It is one of many grandiose illusions relating to the self, and is a phenomenon studied in social psychology.
The hypothesized phenomenon was tested in a series of experiments performed by Justin Kruger and David Dunning, both then of Cornell University. Kruger and Dunning noted earlier studies suggesting that ignorance of standards of performance is behind a great deal of incompetence. This pattern was seen in studies of skills as diverse as reading comprehension, operating a motor vehicle, and playing chess or tennis.
Kruger and Dunning proposed that, for a given skill, incompetent people will:
tend to overestimate their own level of skill;
fail to recognize genuine skill in others;
fail to recognize the extremity of their inadequacy;
recognize and acknowledge their own previous lack of skill, if they can be trained to substantially improve.
Illusory superiority has been found in individuals' comparisons of themselves with others in a wide variety of different aspects of life, including performance in academic circumstances (such as class performance, exams and overall intelligence), in working environments (for example in job performance), and in social settings (for example in estimating one's popularity, or the extent to which one possesses desirable personality traits, such as honesty or confidence), as well as everyday abilities requiring particular skill.
For illusory superiority to be demonstrated by social comparison, two logical hurdles have to be overcome. One is the ambiguity of the word "average". It is logically possible for nearly all of the set to be above the mean if the distribution of abilities is highly skewed. An example is that the mean number of human legs is slightly lower than two, because of the small minority that have one or no legs. Hence experiments usually compare subjects to the median of the peer group, since by definition it is impossible for a majority to exceed the median.
A further problem in inferring inconsistency is that subjects might interpret the question in different ways, so it is logically possible that a majority of them are, for example, more generous than the rest of the group each on their own understanding of generosity. This interpretation is confirmed by experiments which varied the amount of interpretive freedom subjects were given. As subjects evaluate themselves on a specific, well-defined attribute, illusory superiority remains.
Dunning has since drawn an analogy ("the anosognosia of everyday life")to a condition in which a person who suffers 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.
Dunning, Kruger, and coauthors' 2008 paper on this subject comes to qualitatively similar conclusions to their original work, after making some attempt to test alternative explanations. They conclude that the root cause is that, in contrast to high performers, "poor performers do not learn from feedback suggesting a need to improve themselves in work or in the their relations to peers.