Zenner cards and extra-sensory peception
The scientific study of psychic ability probably started with Henry Sidgwick, a professor of philosophy at Cambridge University, who was responsible for exposing charlatans between 1873 and 1880. Over the next forty years the study of psychic ability became more and more scientific.
In the 1920s, Dr Karl Zenner (also reported as Zener) at Duke University, North Carolina, devised a pack of cards that could be used in extra-sensory perception (ESP) experiments. The study of parapsychology, as it was to become known, had become more rigorous. Experiments were conducted from around 1927; several important experiments conducted in the 1930s. Dr J B Rhine and his wife Dr Louisa E Rhine were particularly notable pioneers in ESP research, with Dr J B Rhine being creditied with introducing the terms parapsychology and ESP.
In Zenner-card ESP experiments, one person shuffles the cards so as, to randomise the order of presentation. They then look at each cards in turn. This person is called the sender. A second person – the percipient – then tries to guess the card being sent. Each pack of Zenner cards contain 25 cards; five cards of each symbol. An experiment may require the sender and percipient to go through the pack several times.
The sender and percipient can be in adjoining rooms or at some distance from each other. The main criterion is that they cannot communicate with each other except by using ESP. Even tapping to indicate the next card is being looked at could subconsciously give cues as to the next card, which may over a period of time lead to ESP scores being significant even though ESP was not at work. This is a major problem for designers of ESP experiments.
The Zenner card experiment used here is based on the computer selecting a card.The selected card is programmed to appear on screen, but you cannot see the card because a rectangle is placed over the card. At the end of a round the card is revealed. Zenner card experiments are generally performed blind. This means that the percipient is not aware of the number of cards they have got correct or incorrect. However, this experiment is not performed blind as part of the reason for the experiment is to see how the results change over time.
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