In a nutshell: Clever Hans was a horse that some people thought could do math in his head and understand German. One group of people tested him and found these claims were true. Another scientist tested Hans and found the claims weren’t true.
Clever Hans (German: Kluge Hans) was a German horse who seemed to be able to do math problems in his head, tell time, name people, and answer questions by tapping his hoof. When asked to add 3 + 2, Hans would tap his hoof five times. If asked my name, Hans would have tapped twice for ‘B’, paused, tapped 15 times for ‘O’, paused, and then tapped twice again.
Hans could even answer hard written questions. Was he really able to read?
“If the eighth day of the month comes on a Tuesday, what is the date of the following Friday?” Hans could figure that out. He answered by tapping his hoof eleven times. This was one smart horse!
Hans’s owner, Wilhelm von Osten, began showing his clever horse to the public in 1891. He did so for about twenty years. Many people, including some scientists, were sure that Hans was really doing some heavy duty thinking. They were certain that his hoof tapping was not a trick. Clever Hans became famous.
The German board of education sent a group of people (the Hans Commission) to study Hans. Carl Stumpf, a philosopher and psychologist, led the commission. A few school teachers, a veterinarian, a director of the Berlin zoo, and a few others joined Stumpf.
The Hans Commission listed some possible explanations for what Hans could do. Maybe he could really understand both spoken and written language. Maybe he could do math in his head. Maybe he was acting on cues his owner was giving.
[ . . . ]
a skeptical scientist tests Hans again
[ . . . ]
Oskar Pfungst (1847-1933), a biologist and psychologist, tested Hans again. He found that the Hans Commission had not done a very good job. Pfungst proved that Hans was responding to very slight movements of those watching him. Hans was especially sensitive to small head movements by his owner. Pfungst also found that the movements by those watching Hans were not done on purpose to cue the horse. If asked to add 3 + 2, for example, the horse would start tapping. When he got to five taps, von Osten (or others watching Hans) would lean forward very slightly and that was the cue for the horse to stop tapping.
How did Pfungst figure this out?
He set up a test where the horse could be asked questions but could not see von Osten or others who were watching. He put blinders on Hans. When the horse couldn’t see anyone, he didn’t respond. In another test, the horse didn’t respond when the one asking the question didn’t know the answer to it. But the horse did give the right response when the one asking the question did know the answer to it, even if von Osten was not present. That last test ruled out the hypothesis that von Osten knew he was signaling Hans. He wasn’t cheating. He really believed his horse was doing math and reading letters. The evidence collected by Pfungst led the scientific community to hold that Hans was responding to slight movements rather than understanding written and spoken words. Von Osten, however, kept on believing that his horse could read, do math, and understand German. He was making a little bit of money showing off Hans and he kept on with his pony show.
One of the beautiful things about science is how one discovery leads to another. One of the things Pfungst found is the ideomotor effect: making slight movements without being aware of making them. (See the entries on dowsing and the Ouija board for other cases of the ideomotor effect.)
While testing Hans, Pfungst discovered that animals respond to movements around them that can barely be seen. He also found that people aren’t always aware that they are moving and giving cues to animals (or other persons). We now know that humans also respond to movements or sounds without being aware of it. We call this giving of signals without awareness unconscious signaling. This discovery has had a major effect on how experiments should be done when they involve either people or animals.
We now know that humans are unconsciously aware of many things right before their eyes. A botanist might see a rare flower out of the corner of his eye and not be conscious of having seen it. Later, he finds himself thinking of that rare flower. Then, he sees the flower and says “wow, I was just thinking of that flower.” Isn’t that amazing? Yes. Scientists call it “sensing without seeing.”
Geoffrey Dean via The Committee for Skeptical Inquiry – CSI
Today, phrenology (“head reading”) is usually seen as the fossilized stuff of cranks and charlatans. But in the nineteenth century it had a huge influence at all levels of Western society, more than all of its later competitors (such as psychoanalysis) put together. It was influential because of its attractive philosophy and because practitioners and clients saw that it worked. But we now know that it could not possibly work; personal experience had led millions of people astray. Indeed, few beliefs can match phrenology for its extent of influence and certainty of invalidity. So it has valuable lessons about any experience-based belief.
In the nineteenth century, phrenology affected all levels of Western life and thought. In Britain, Europe, and America, its influence was felt in anthropology, criminology, education, medicine, psychiatry, art, and literature. In France, it eroded established power and led to wide social changes. In Australia, it rationalized the violence against Aborigines and explained the criminality of convicts. For ordinary people everywhere a head reading was often required for employment or marriage.1 But how could this happen if phrenology was totally invalid? For answers, we need to start at the beginning.
First Steps to Delusion
Around 1790, the German-born anatomist Franz Joseph Gall, one of the founders of modern neurology, put together his skull doctrine that later led to phrenology. He held that behavior such as painting or being careful had their own specialized organs in the brain, and that they influenced the shape of the skull. So the skull’s bumps would indicate behavior and abilities that were innate. Gall spent eleven years examining hundreds of heads to test his ideas: “If … he observed any mechanician, musician, sculptor, draughtsman, mathematician, endowed with such or such faculty from birth, he examined their heads to see whether he might point out a particular development of some cerebral part…. He also called together in his house common people, as coachmen and poor boys, and excited them to make him acquainted with their characters” (Spurzheim 1815, 271).
Gall’s seemingly logical approach had two fatal defects. First, his claims were often based on a single striking case, for example “Cautiousness” was placed above the ears because an extremely cautious priest had a large bump there. Second, Gall looked only for confirmingcases and ignored disconfirming cases, a flaw not lost on his critics. Thus David Skae (1847), a physician at the Royal Edinburgh Asylum, noted that once the truth is “fixed upon our minds,” looking for confirmation is “the most perfect recipe for making a phrenologist that could well be devised.” But to Gall and the thousands of phrenologists who came later, personal experience mattered more than procedural defects. Phrenology had taken its first giant step on the road to delusion.2 Note that the delusion of experience is not limited to artifacts of reasoning such as the Barnum effect.
MORE . . .
- The phrenomagnetists, 19th century scientists of the mind (sillyverse.com)
- Reading The Bumps (Part 1) (drvitelli.typepad.com)
- Examining photographs of Einstein’s brain is not phrenology! (oup.com)
- Who cares about Einstein’s brain? (psychologytoday.com)
- phrenology today (3quarksdaily.com)
- Myths About Our Right and Left Brains (psychologytoday.com)