About 25 years ago, the psychologists David Dunning and Justin Kruger ran a series of experiments to reveal something strange: people who know the least often have the most confidence in their abilities. This has come to be known as the "Dunning–Kruger effect." In short, if you're incompetent, you lack the skills you need to recognise your own competence, and so you overestimate your abilities. You think you're great when you're not. But what's less commonly known is the opposite, known as the "