Clever Hans was a horse allegedly able to accomplish complex intellectual tasks like math, reading, spelling, telling time, and understanding German. Hans would answer questions by tapping his hoof. Asked how much is two plus nine, Hans would stamp his hoof eleven times. Questions could be asked either verbally or written. Seldom if ever was Hans ever wrong. Upon an investigation by a psychologist in 1907, it was shown that Hans had been simply reacting to body language cues from the audience. When his audience gasped, anticipating Hans' arrival at the correct answer, the horse would stop tapping. We still think that horse is pretty impressive!