Ever wonder how the subject of non verbal communication ever came to our attention? The answer is Clever Hans Phenomenon and it dates back to the early 1890's. It refers to a form of involuntary and unconscious cuing that sometimes happens in communication and the story itself is about a horse who responded to questions requiring mathematical calculations by tapping his hoof. Sound familiar?
If asked by his master, William Von Osten, what is the sum of 3 plus 2, Hans the horse would tap his hoof five times. It appeared the animal was responding to human language and was capable of grasping mathematical concepts. In 1891 Von Osten began showing Hans to the public and the horse amazed all who saw him.
It was eventually discovered by Oskar Pfungst, however, that the horse was responding to subtle physical cues (what is called ideomotor reaction). In other words Hans was responding to a simple, involuntary postural adjustment by the questioner, which was his cue to start tapping, and an unconscious, almost imperceptible head movement, which was his cue to stop. Yet, more than a dozen scientists observed Hans and were convinced there was no signaling or trickery. They were impressed that Hans performed almost as well without Von Osten as with him. But the scientists were wrong.
The horse was simply a channel through which the information the questioner unwittingly put into the situation was fed back to the questioner. The fallacy involved treating the horse as the source of the message rather than as a channel through which the questioner's own message is reflected back. The key here is that it happens unconsciously. Von Osten was not engaging in fraud - he just didn't quite realise just how clever his horse really was.
Pfungst noted that when the correct answer was not known to anyone present, Clever Hans didn't know it either. And when the horse couldn't see the person who did know the answer, the horse didn't respond correctly. This led Pfungst to conclude that the horse was getting visual cues, albeit subtle ones. It turned out that Von Osten and others were cuing Hans unconsciously by "tensing their muscles until Hans produced" the correct answer. The horse truly was clever, not because he understood human language but because he could perceive very subtle muscle movements. More important, Pfungst discovered that people can unconsciously communicate information to others by subtle movements and that some animals can perceive these unconscious movements. It was only a matter of time before psychologists would be investigating nonverbal influence among humans.
So there you go - the story of a remarkable horse and the origins of the study of non-verbal communication. It is just a pity we don't recognise this remarkable facility for intuition that some animals and humans have and instead focus on the nonsensical pseudoscience offered up by psychics, personality profilers and quacks of all descriptions when, if genuine, they are just sensitive to the unconscious signaling of others.