In 1904, a German mathematics teacher by the name of Mr. von Osten, believed that he had taught his horse, Hans, to add, subtract, multiply and divide. As if that wasn’t enough, Clever Hans, as the horse became known, could also spell, read, solve problems of musical harmony and answer personal questions – all with taps of his hoof.
Mr. von Osten didn’t use Hans to make money and was quite happy to absent himself when Hans was being asked questions. Clever Hans was a world-wide phenomenon. In September, 1904, The New York Times ran an article on Clever Hans – Berlin’s Wonderful Horse: He Can Do Almost Everything but Talk – How was he taught?
The German government appointed The Hans Commission to investigate the claims made about this horse. This team was led by Carl Stumpf, the philosopher and psychologist, and included the director of the Berlin zoological gardens, a vet, a circus manager, a Cavalry officer, and a number of school teachers. In 1904, this team concluded that there was no fraud involved and that indeed Hans the Horse could do all the things his master claimed.
The Hans Commission passed the investigation over to Oskar Pfungst – an associate of Stumpf. Pfungst confirmed the findings of the Commission – there really was no fraud involved, however, he also discovered that clever as Hans was, he wasn’t really the wonder horse he appeared to be.
Pfungst discovered, after many tests, that Hans could only get the correct answer, if the asker knew the answer. Once Pfungst realised this, he changed the focus of his study from the horse to the questioners, and it was here that he made some very important discoveries.
Pfungst found that the reason Hans could answer questions was that the questioners all exhibited a number of subtle, involuntary and unconscious signals that the horse could ‘read’. For example, a common occurrence was that as Clever Hans’ taps approached the correct answer, all questioners would display tell-tale postural and facial signs of tension that were released as the horse made the final tap. This was how Hans knew he had arrived at the correct answer. Neither consciousness of the possibility of giving these signals nor attempts not to give them were successful. These are involuntary cues in the truest sense of the word.
Without fail, according to Pfungst, questioners give hints and cues that are interpreted by the respondent. This phenomenon became known as the Clever Hans Effect. Even today, comparative psychologists – who study animal behaviour – generally test animals in isolation to avoid this effect.
Human being are equally susceptible to the Clever Hans Effect. Our expectations are not just vague, harmless whims but can actually influence outcomes and as such deserve some serious attention…
Tomorrow – Human Nature – A Conceptual Framework – IV
