In the early 1930's a man named Karl Zener developed an experiment in which he believed tested a person's level of ESP. In order to conduct this experiment Zener designed five white cards, each with its own unique symbol. The symbols included a hollow star, a hollow circle, a cross that looked similar to a plus sign, a hollow square, and three wavy lines. Five of each card was then shuffled together to form a deck of twenty-five cards each. These were known as "Zener cards", named after Karl Zener. This deck of cards was held by the experimenter and then another person would try to use ESP to read the experimenter's mind and see which card was on top. The receiver was not told whether they were right or wrong with their choices until they were done the whole deck, so they couldn't eliminate cards, and as a result increase the chance of getting one right through guessing. Next they would take a look at the results and see whether a person possessed ESP. A person would get about 20% correct base off of chance, so anything higher would show evidence of ESP. Based off of this criteria certain people tested positive for ESP. However after some people claimed these were results of the participants cheating somehow, so Zener began watching over the experiments more diligently to eliminate the possibility. After this was implemented the tests became less successful. Another factor that can be looked at when trying to explain how people were able to guess right so often without the use of clairvoyance or any other ability granted through ESP is the misinterpretation of statistics. People tend to disregard the bell curve when reading the results because they let their desire for ESP to be a reality cloud rational thinking. The bell curve states that most people are going to score around the 20% marker, which is the normal result when considering chance, but probability predicts that there will be a small percent that will score above the 20% as well as below it. Even now there are many websites online that allow people to take the Zener Card Experiment. This goes to show that people still believe that the results of these tests are accurate and shouldn't be disregarded as simply chance.
Shermer, Micheal. "Why People Believe Weird Things: Pseudoscience, Superstition, and Other Confusions of Our Times"