THE OTHER END OF THE LEASH
Clever Hans Revisited
by Patricia McConnell
You probably know the story of Clever Hans, the horse owned by a math teacher named von Osten who decided to teach his horse to do math in the same way that he did his pupils. After extensive training, Clever Hans appeared able to solve relatively advanced mathematical problems, including multiplication and long division. Clever Hans showcased his abilities around Europe, although von Osten never charged for an exhibition. His owner and trainer sincerely believed that his horse understood what he was being asked, and wanted the world to see it for themselves.
Scientists were so interested that a panel was formed, led by psychologist Carl Stumpf, which verified that no tricks were visibly involved, but passed the issue onto psychologist Oskar Pfungst. After an extensive series of tests, Pfungst found that Clever Hans was unconsciously being cued by his trainer. Hans could only answer questions if in visual range of a human who knew the answer. In other words, Pfungst found that Clever Hans was clever indeed, but in a different way than thought by his owner. The horse used subtle cues from humans (head tilt, eyebrow raise) to know when the correct number was coming, and thus when to stop pawing. (Hans communicated by pawing the ground; his answer to 2 + 2 was to paw the ground 4 times.)
I’m reprising this story, familiar to most of you, because of a great talk given by Dan Estep and Suzanne Hetts of Animal Behavior Associates at the Interdisciplinary Forum on Applied Animal Behavior in Arizona last weekend. The owner of a dog named Sheba had asked for a “scientific investigation” into his dog’s intelligence, and a local TV station asked Dan and Suzanne to look into it.