The Dunning-Kruger effect is where people of low ability (those who fail to answer logic puzzles correctly) tend to overestimate their abilities. The findings from the original paper on the effect found that the worst performers (those with the lowest ability) grossly overestimated their ability (and the best performers underestimated it).

The explanation for this effect is that when we’re not good at a task, we don’t know enough to accurately assess our ability. Inexperience casts the illusion of expertise.