Clever Hans’ Horseshoes

Origin
Clever Hans (in German, der Kluge Hans) was an Orlov Trotter horse that was claimed to have been able to perform arithmetic and other intellectual tasks. After a formal investigation in 1907, psychologist Oskar Pfungst demonstrated that the horse was not actually performing these mental tasks, but was watching the reaction of his human observers. Pfungst discovered this artifact in the research methodology, wherein the horse was responding directly to involuntary cues in the body language of the human trainer, who had the faculties to solve each problem. The trainer was entirely unaware that he was providing such cues. In honour of Pfungst's study, the anomalous artifact has since been referred to as the Clever Hans effect and has continued to be important knowledge in the observer-expectancy effect and later studies in animal cognition. Hans was studied by the famous German philosopher and psychologist Carl Stumpf in the early 20th century. Stumpf was observing the sensational phenomena of the horse, which also added to his impact on phenomenology.

Effect
When one of the horseshoes is held, the user is able to read the minds of horses.