Cognition and perception, Personality and self David Dunning responds to our March cover feature. The Dunning-Kruger effect suggests that unknowledgeable people lack the very expertise they need to recognise their lack of expertise. They thus overrate their knowledge and performance. Put more technically, deficient cognition (i.e., expertise) leads to faulty metacognition (i.e., self-evaluation of expertise). In contrast, highly expert people underrate their skills socially because they overestimate the