... difficulties in recognizing one's own incompetence lead to inflated self-assessments.
Kruger, J., & Dunning, D. (1999). Unskilled and unaware of it: How difficulties in recognizing one's own incompetence lead to inflated self-assessments. Journal of Personality and Social Psychology, 77(6), 1121–1134
The Dunning-Kruger effect is
is a cognitive bias in which people with limited competence in a particular domain overestimate their abilities
The definition above is a transcript of Wikipedia. But I would like to focus in two aspects stemming from this bias:
The most recognizable result of the Dunning-Kruger effect is the impostor syndrome. Note this syndrome was described earlier, in 1978 by psychologists Pauline Clance and Suzanne Imes; in that study it was revealed that women that had achieve a high level of success saw themselves as impostors: just a result of a chance, a mistake of others or simply a fraud.
The Imposter Phenomenon in High Achieving Women: Dynamics and Therapeutic Intervention
The impostor syndrome has gained some traction in the last years (today is 2024) and is a household term over the Internet -though I could not locate where this popularization comes from-.
The most interesting aspect for me, out of my experience along my career, is the self-confidence of certain people when dealing with a complex subject, when those people have just barely scratched the surface of that topic; or just started to apply that knowledge.
Expert derives from experience; but the experience needed to master a topic is far from the limited experience of these -allegedly- experts.
I do not dare to say that the rule of 10,000 hours is the only valid criteria to define experience (the rule says it takes 10,000 hours of practice to master a complex subject; rule popular by Malcolm Gladwell's book Outliers: The Story of Success, based on an earlier article from 1993 by Ericsson, K. Anders Krampe, Ralf T. Tesch-Römer, Clemens).
My rule of thumb to identify unexperienced is:
either the first contact of a person with a subject
or the first time a person uses a technology to solve a problem
This second aspect (that mastering a subject does not implies its convenience to solve a particular problem) is, perhaps, the most counter-intuitive thing for an expert, but collectively we cannot help thinking everything looks like a nail when one has a hammer in his hand.