In a logic test administered to people who had volunteered over the internet, a team of researchers found that the lowest scorers vastly overestimated their performance, believing, on average, that they had gotten 7 out of 10 items right, when the actual figure was 0, according to Thomas Schlösser of the University of Cologne in Germany. People who lack the skill to perform well also tend to lack the ability to judge performance (their own or others’); because of this “dual curse,” they fail to recognize how incompetent they truly are. But skills aren’t set in stone: Teaching poor performers to solve logic problems causes them to see their own errors and reduce their previous estimates of their performance.

Source: How unaware are the unskilled? Empirical tests of the signal extraction counterexplanation for the Dunning-Kruger effect in self-evaluation of performance