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| originally made out of a flimsy material.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