144. Clever Horse?

The picture shows "Clever Hans" the horse performing one of his many arithmetic tasks by tapping out his hooves. Later on it was discovered that the horse would pick up involuntary postural clues from its trainer which would help it arrive at the right answer in a majority of cases, if not all. This is turn gave rise to the Clever Hans effect which is an important artifact in animal cognition and observer-expectancy effects.....