I am just doing some extra reading for my equine behaviour module and I came across "Clever Hans". I learnt about this horse in psychology A level and it is an interesting story.
Clever Hans was a horse that lived in Austria in the 1900s. The horse was thought to be an arithmetic genius. It appeared that he was able to count and could also do algebra. He would count out the answer by pawing with his leg and would always stop at the correct number.
After scientists taking great interest in this horse and why it was so clever they found that it only got the correct answer when it could see the audience. If there was a board between them it got the incorrect answer.
The horse had learnt to read the body language of the audience and when he got to the correct answer he would stop due to changes in their body language. He learnt he would get a reward after doing this as well. His owner was thought to be the main person he looked at for these cues and his bowler hat, seen below was thought to accentuate his movement of leaning forward slightly as the horse got to the correct answer.
This shows how horses pick up on very small body language signals. This has developed from them living in herds where body language is a very important part of their communication. As they are prey animals, they often prefer communicating in this way as opposed to using vocal noises which could alert predators.