Clever Hans

Clever Hans was a horse who seemed to be able to solve arithmetic exercises.

The horse was introduced with a simple math exercise. e.g:2+3=?

The horse gave the answer by tapping his leg on the ground.

How does the horse knows the answer? Simple, the horse is sensitive to the reactions of the people around him. The people expected him to give the right answer and not deliberately signal the horse when to stop tapping.

 

Placebo effect ►

 

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See also

• Can people predict the future?
• Is mind reading possible?
• Do black cats bring bad luck?
• Is astrology real or fake?
• What is magic?