If you’re not a huge fan of public speaking, you’re in good company. It’s such a widely shared source of anxiety that when psychologists want to induce unpleasant stress in a person for experimental purposes, they often use a public speaking task called the Trier Social Stress Test. The test requires people to give a talk and do sums in front of a panel of impassive listeners, and it reliably generates stress markers such as a faster heart rate, raised cortisol levels, and “enhanced skin conductance,” which is the polite way of saying sweaty palms.