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| cards were originally made out of a | | | | averaged in with the other six tests |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