Clever Hans

Wilhelm von Osten, a German math teacher, wanted to prove that animals were smart. So, in the early 1900’s he taught a horse named Hans to do math. People were impressed. Hans would tap his hoof to solve almost any problem. Hans was even nicknamed Clever Hans. Eventually, however, psychologists figured out the truth. Wilhelm was giving Hans the answers via nearly imperceptible movements of his face. The craziest part? He wasn’t doing it on purpose. Although Wilhelm refused to believe it, today we refer to such a situation as the “Clever Hans Effect.”