The Dunning-Kruger effect is a cognitive bias in which individuals are prone to assess their cognitive ability as greater than it truly is. Most simply, individuals who are the least competent at a task often incorrectly rate themselves as high-performing even when they lack particular knowledge or expertise.

“I am wiser than this man, for neither of us appears to know anything great and good; but he fancies he knows something, although he knows nothing; whereas I, as I do not know anything, so I do not fancy I do. In this trifling particular, then, I appear to be wiser than he, because I do not fancy I know what I do not know.”

—attributed to Socrates, from Plato, Apology