Tuesday, 31 March 2009
Clever Hans and observer expectancy effect
No this isn't a pun on hands it's actually the name of a horse. Called Hans. Who was...wait for it....clever! Yes a clever horse who could count and do simple arithmetic by tapping out numbers with his hoof. The case amazed all of Germany (and probably the world) in the early 20th Century. He amazed so many people that an eminent psychologist called Oskar Pfungst was called in to investigate Hans in 1907.
Pfungst's studies established that Hans was, sadly, unable to count or make simple sums. His gift was an uncanny ability to read the expectation on the face and in the body language of his owner who would ask him questions. When the answer was five (for example), the owner would (inadvertently) give off signals for the horse to stop tapping his hooves when five had been reached. He couldn't repeat this when the owner wasn't in sight. Hans seems to have had an ability to read these visual clues in order to please his owner (and possibly get a food reward).
I thought of this the other night in training because when we train in partners we tend to do this too. No, not tap our hooves to count but we do give off 'expectation' in our expressions. What is meant to be 'spontaneous' attack is sometimes telegraphed by these expressions or even simply an eyebrow raise! In Tang Soo Do a kihap is often performed by both attacker and defender to ensure everyone is ready and from that point onward the attack can be initiated at any moment. In practice the kihap is perfunctory and initiates the technique. This shouldn't be the case. We need to stay focused and ready to receive the attack at any time and without telegraphing by the attacker. No raised eyebrows, head lifting or hoof tapping.
So Hans couldn't count but he could read his owner's subtle body and facial language. We should train with this in mind.