The Kruger - Dunning Effect or Why the world is the way it is?

“In the modern world the stupid are cocksure while the intelligent are full of doubt.” — Bertrand Russell

I first noticed this 'effect' a few years ago when engaging students in a peer/self assessment process. It was very marked that clearly weaker individuals seemed to consistently rate themselves very highly, 80-90% out of a hundred - and clearly stronger people would rate themselves at about 40-50%.

At first I thought that the weaker students were being deliberately obtuse or simply trying to obstruct the assessment process - but no - they actually thought that their work deserved the 80-90% they had assigned themselves - even to the extent that they couldn't understand how lecturers and their peers rated them much lower.

On the other hand, stronger students would tend to be much more critical of themselves - the very critical faculties required to allow them to produce quality work was also being used by the students themselves to be too harsh on their own perception of their own skills.

The Dunning–Kruger effect is a cognitive bias in which "people reach erroneous conclusions and make unfortunate choices but their incompetence robs them of the metacognitive ability to realize it."

The unskilled therefore suffer from illusory superiority, rating their own ability as above average, much higher than in actuality; by contrast, the highly skilled underrate their abilities, suffering from illusory inferiority. This leads to a perverse result where less competent people will rate their own ability higher than more competent people. It also explains why actual competence may weaken self-confidence because competent individuals falsely assume that others have an equivalent understanding. "Thus, 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 demonstrated in a series of experiments performed by Justin Kruger and David Dunning, then both of Cornell University. Their results were published in the Journal of Personality and Social Psychology in December 1999. However, the phenomenon had been assumed by many philosophers for nearly a century prior to Kruger and Dunning's study (see Russell quote above).

Kruger and Dunning noted a number of previous studies which tend to suggest that in skills as diverse as reading comprehension, operating a motor vehicle, and playing chess or tennis, "ignorance more frequently begets confidence than does knowledge" (as Charles Darwin put it). Kruger and Dunning hypothesized that with a typical skill which humans may possess in greater or lesser degree:

Incompetent individuals tend to overestimate their own level of skill.

Incompetent individuals fail to recognize genuine skill in others.

Incompetent individuals fail to recognize the extremity of their inadequacy.

If they can be trained to substantially improve their own skill level, these individuals can recognize and acknowledge their own previous lack of skill.

The authors draw an analogy with anosognosia—a condition in which a person who suffers a physical disability due to brain injury seems unaware of or denies the existence of the disability. This may include unawareness of quite dramatic impairments, such as blindness or paralysis.

Kruger and Dunning won Ig Nobel Prizes in Psychology in 2000 with their report, "Unskilled and Unaware of It: How Difficulties in Recognizing One's Own Incompetence Lead to Inflated Self-Assessments".