It turns out that failing to stop by the sink on your way out of the bathroom might not just be down to laziness. From a person’s style of thinking to their degree of delusional optimism, the need to feel “normal” and the potency of their feelings of disgust, a number of psychological factors are subliminally discouraging people from washing their hands. By understanding these hidden biases, experts around the world are hoping they can lure us into becoming more hygienic.

“One problem with handwashing is that, especially in developed countries, you can avoid washing your hands lots and lots of times and you won’t get ill,” says Aunger. When it does make you ill, it’s often days later, by which point that time you forgot will have long vanished from your memory. “Even with coronavirus, they’re saying the delay between being infected and seeing any symptoms is like five, six days, so the connection is very difficult to make.”