| Zener cards were developed and designed by | | | | implemented as testing progressed including |
| Karl Zener, a Swiss Psychologist, and his | | | | the use of partitions and separate rooms for |
| associate J.B Rhine, at Duke University | | | | the tester and subject. This ensured that the |
| during the 1930's, to test an individual's | | | | chance of cheating would be minimized. |
| psychic abilities or ESP (Extra Sensory | | | | |
| Perception). Zener cards can test many types | | | | The analysis of the tests outcome was based |
| of psychic abilities including the ability to | | | | on pure statistics. As the deck was |
| perceive objects or events that already exist | | | | constructed of 5 different cards the overall |
| or have occurred, but are not known to you | | | | probability of getting the correct answer by |
| (clairvoyance); your ability to see the | | | | chance would be 1 in 5 or 20%. Several tests |
| future (precognition); and the ability to | | | | were conducted to approach a normal |
| transfer thoughts or feelings via a medium | | | | distribution and eliminate any significant |
| other then the 5 senses (telepathy). | | | | chance for statistical anomalies to affect |
| | | | the results significantly. For example: on |
| The deck consisted of 25 cards made up of 5 | | | | one test set an individual guesses 50% |
| subsets of identical cards. The pictures on | | | | correct but on the next 6 test sets the |
| the 5 cards consisted of a cross, waved | | | | individual averages 10% this would identify |
| lines, a hollow circle, a hollow star, and a | | | | the first test as being anomalous and either |
| hollow square. The cards were originally made | | | | thrown out or averaged in with the other six |
| out of a flimsy material. This material was | | | | tests diminishing its statistical impact. For |
| later determined to be biased due to its | | | | example the 6 runs at 10% would be 85.7% of |
| translucence which allowed individuals to see | | | | the weight in the average and the 50% would |
| the shapes through the cards. So, subsequent | | | | be 14.3% of the average so 10 * .857=8.57 + |
| decks utilized a thicker card stock to | | | | 50*.143=7.15%= an avg. of 15.72% accuracy. To |
| eliminate the bias and lend credibility to | | | | be considered to have ESP one would have to |
| the statistical data. | | | | continually score higher than 25% on the |
| | | | Zener card test to be statistically |
| The test for clairvoyance consisted of the | | | | significant. |
| person conducting the test, subject being | | | | |
| tested, and third party witnesses. The | | | | In conclusion Zener and Rhine especially |
| experimenter shuffled the deck of cards then | | | | Rhine and his wife are considered to be the |
| selected a card in the deck looked at it | | | | founders of modern day Para-Psychology and |
| asked the subject what it was and recorded | | | | Karl Zener considered the inventor of the |
| the data until the entire deck had been | | | | Zener cards which to this day are still used |
| exhausted. In addition further controls were | | | | to test for psychic abilities. |