You'd Better Believe It!

There are two types of dogs in this world, companion dogs and working dogs. Man has had working dogs for a very long time, but also quite likes having them around.  For their part, dogs mostly prefer having people around rather than other dogs. At a very early age, they learn visual cues from our voice, face and general body language for what we want from them. Of course, some of us are better at communicating than others, and we have dogs to match.

The sniffer dog has emerged over the last thirty years as a common sight in many public locations. That’s where we see the ones with small teeth like beagles or spaniels. The ones with big teeth, like Belgian malinois are more likely to be found with the military or police.

Explosives and drugs are the common target for the connoisseur’s nose, although diabetes and cancer are bringing them into the medical field. The problem is that they want to please us and a great way making us happy is to confirm our prejudices.  Lit et al (1) made a study of how the beliefs of the handlers affected their dog’s performance.

They took a church and used eighteen trained noses, with their handlers of course, to check out some side rooms for drugs or explosives. You and I know that there would be neither in such a place, but the handlers and dogs didn’t. Some rooms had decoys for the dogs consisting of Slim Jim sausages and a tennis ball, while decoys for the handlers were less interesting. These were little squares of red paper. The decoys were mixed and matched, and some rooms had neither.

Well, only 15% of the runs indicated that there were no drug or explosive caches in the church. The bits of red paper were a great attraction.  The sausages were also a bit of a distraction. Only one team got it right on two runs through.

Although sausages were difficult to resist for both parties, the bits of red paper were only important to the handlers and made them believe that there were illicit goods hidden somewhere. Wittingly or unwittingly, that belief was transmitted to their dog, which did it’s best to please.

The unwitting transmission of information is called the “Clever Hans Effect” after Wilhelm van Osten and his grumpy horse, Hans, who would do counting tricks for money back in the early 1900s (2). Professor Pfungst checked the horse out and found it only got the right answer if the questioner already knew the answer and the horse could see the questioner. He, the horse Hans, got very grumpy if he got it wrong and bit the poor Professor Pfungst for his pains.

  1. L.Lit, J.B.Schweitzer & A.M.Oberbauer, Animal Cognition, 14, 387, (2011).
  2. The New York Times. 1904-09-04

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