 Clever Hans was a particularly clever horse, able to interpret his masters body language while carrying out simple arithmetic and answering various simple questions.These involuntary movements made by the owner Mr von Osten, were unconscious and led to the horse being able to correctly answer questions based on the very subtle angle changes of Mr von Osten’s head.This case study was often cited by scientists as reasoning against the validity of using this methodology because this singular case was proved to be inaccurate.