der kluge Hans

The following are notes from Season 2 Episode 13 of the Who’d a Thunk It? Podcast. If you prefer to listen to this content just mosey on over to my Podcast hosted by by clicking: Who’d a Thunk It?

  • Recommendation Segment!!!
    • For this episode I wanted to recommend a book I listened to this past winter: Sapiens.
    • I think I would call it an educational book, but it doesn’t feel boring like most educational books might. It is about the story of man as far as we know it and a bit about where we are going (our future).
  • The Realm of the Scientific Method
    • In November of 1859 Charles Darwin’s On the Origin of Species by Means of Natural Selection was published and sold out immediately. This publication introduced the world to the theory of evolution.
    • In the decades that followed humanity’s world view began to shift.
    • Evolution provided so many answers to scientific questions (namely biology), it proposed contradictory claims to religious world views, but perhaps the most astonishing change the Theory of Evolution had on the world was its ability to spread among the common man therefore influence how the vast majority of humans saw the world.
  • A Time of Discovery
    • Because of Darwin’s discovery, everyday people began to show an increased amount of interest in animals.
    • One such everyday man, Wilhelm von Osten, began ponder the intelligence levels of the animals around him. Wilhelm von Osten was a gymnasium mathematics teacher, an amateur horse trainer, phrenologist, and something of a mystic.
    • Wilhelm von Osten took one of his prize stallions named Hans and trained him to communicate by tapping his hoof. In time, Hans was trained to solve math equations, identify colors, read and spell, and even identify musical tones. When asked to do so, Hans the stallion was providing answers that rivaled the intelligence of most humans during that time.
    • Von Osten would ask Hans, “If the eighth day of the month comes on a Tuesday, what is the date of the following Friday?” Hans would answer by tapping his hoof eleven times. Questions could be asked both orally, and in written form.
    • Wilhelm von Osten would write a problem on a chalk board, display it to Hans and wait for Hans to start tapping his hoof. Using this method, Hans was able to give a correct answer about 90% of the time. Whenever Hans tapped his hoof the correct number of times, Wilhelm von Osten gave the horse a tasty treat.
  • The Skepticism of Psychology
    • News of this incredibly intelligent horse spread fast. Everyone was talking about Clever Hans (or “der kluge Hans” in the original German language).
    • Von Osten exhibited Hans throughout Germany, and never charged admission. Hans’s abilities were reported in The New York Times in 1904.[3]
    • the German Government launched a formal investigation. A total of 13 people were asked to look in to Clever Hans and to see if any fraudulent behavior was afoot, or to see if Hans really was a genius horse.
    • Among this panel of 13 investigators was a Circus Manager, Zoo Director, Veterinarian, Calvary Officer, and a they were all lead by the Philosophy/Psychologist Carl Stumpf. Together they were known as the Hans Commission.
      • This commission concluded in September 1904 that no tricks were involved in Hans’s performance. They were ready to declare Hans a genius horse until a student at the Psychological Institute at the University of Berlin named Oskar Pfungst decided to throw his 2 cents in to the investigation.
  • The psychologist Oskar Pfungst – decided to run more tests on Hans and Wilhelm von Osten by:
    • Isolating horse and questioner from spectators, so no cues could come from them
    • Using questioners other than the horse’s master
    • By means of blinders, varying whether the horse could see the questioner
    • Varying whether the questioner knew the answer to the question in advance.
  • Pfungst ran a lot of trials to rule out as much as he could.
    • First he separated Hans from Von Osten. Hans was still able to get the answers correct without Von Osten present which ruled out fraud. So Von Osten wasn’t deliberately trying to hoodwink the public.
    • But then through more trials Pfungst found that Hans’s level of success depended upon whether the human questioner was within eyesight and knew the answer themselves.
      • So if Von Osten (or anyone else asking the questions) was given a chalk board with a question on it, but wasn’t allowed to look at the question themselves, Hans had about a 6% success rate.
      • Also whether the human questioner did or did not know the answer was irrelevant if Hans was unable to see the questioner.
      • If Hans could see the person asking the question AND that person knew the answer to the question then Hans gave the correct answer about 90% of the time.
  • So here’s the point where I ask you, my listeners (and/or blog readers) to think. How is Hans able to get the right answer so often under these specific conditions, but when these conditions aren’t met he only gets 6% of the answers right?

=============Think for a second. You got it? ============

  • Pfungst concluded that through Wilhelm Von Osten’s training method, Hans was very clever, but not how you think.
    • No, Hans did not understand math, language, or music.
    • Instead, Hans was able to read the human questioner’s body language to determine at which hoof tap he was expected to stop.
      • As the horse’s taps approached the right answer, the questioner’s posture and facial expression changed in ways that were consistent with an increase in tension, which was released when the horse made the final, correct tap. This provided a cue that the horse could use to tell it to stop tapping. The social communication systems of horses may depend on the detection of small postural changes, and this would explain why Hans so easily picked up on the cues given by von Osten, even if these cues were subconscious.
    • So by human standards Hans was no genius, but he was able to read body language MUCH more fluently than us humans.
      • I bet Hans was a killer at the poker table. lol horse humor
    • Von Osten disregarded these findings. Dismissing Pfungst’s meticulous use of the scientific method to determine the source of Hans’s success, Wilhelm Von Osten went on to tour Europe with Hans. They continued to gather large crowds.
  • The rigor of Pfungst’s trials and the detail of his observation are considered classic early examples of experimental design in behavioral psychology.
    • After Pfungst had become adept at giving Hans performances himself, and was fully aware of the subtle cues which made them possible, he discovered that he would produce these cues involuntarily regardless of whether he wished to exhibit or suppress them. Recognition of this phenomenon has had a large effect on experimental design and methodology for all experiments whatsoever involving sentient subjects, including humans.
    • The Clever Hans Effect has also been observed in drug-sniffing dogs. A study at University of California, Davis revealed that cues can be telegraphed by the handler to the dogs, resulting in false positives.
    • Pfungst’s final experiment showed that Clever Hans effects can occur in experiments with humans as well as with animals. For this reason, care is often taken in fields such as perceptioncognitive psychology, and social psychology to make experiments double-blind, meaning that neither the experimenter nor the subject knows what condition the subject is in, and thus what their responses are predicted to be. 
  • So the world of Psychology grew quite a bit from the story of Clever Hans, but what happened to the horse himself?
    • After von Osten died in 1909, Hans was acquired by several owners. After 1916, there is no record of him and his fate is unknown.
    • Although highly unlikely (more like virtually impossible), perhaps “der kluge Hans” is still out there somewhere, tapping his hoof in beautiful symphony of music or solving mathematics’ greatest problems.
  • Thanks for listening Who’d a Thunkers! Check out the accompanying blog post for a visual component to the episode, link in description.
  • Until next week! Catch you later 🙂


If you prefer to listen to this content just mosey on over to my Podcast hosted by by clicking: Who’d a Thunk It?

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