Germany's board of education asked to conduct an independent investigation into Hans' abilities, and Von Osten agreed. He was a man of science, after all, and he knew that there was no fraud to expose. The board members assembled a number of scientific minds to join the Hans Commission, including two zoologists, a psychologist, a horse trainer, several school teachers, and a circus manager. Following extensive independent testing, the commission concluded in 1904 that there was no trickery involved in Hans' responses; as far as they could tell, the horse's talents were genuine.
The Hans Commission then passed the investigation on to Oskar Pfungst, a psychologist with some novel ideas on how to best unravel the mystery. Pfungst erected a large tent to house his experiments, thereby removing the contaminating effects of outside visual stimuli. In order to produce a sufficient data set, the scientist compiled a very large list of questions, and carefully outlined the different variables that were to be considered. Thus Pfungst began his interrogation of Hans.
Click the link to read the rest of the story. I liked how the conclusion of the experiments, while not the answer people wanted, added something to our body of knowledge. That's what science is all about.