When the horse could answer the question, it started to tap more slowly when it got near to the right answer. Then it stopped when it got to the right answer. This showed that the horse was watching the person asking the question, and could sense when the person was expecting him to stop. Von Osten probably did not realize that he was giving the horse signals just by looking at him. The horse was, indeed, clever to guess what was wanted of him, but of course it did not understand the mathematics. The final proof was that Pfungst discovered how to signal to the horse, by slightly raising his eyebrows. Then he could get the horse to give any response he wanted.