Zener cards: what are they and why do they not show cases of telepathy?

Do telepathy exist? And clairvoyance? These two questions are very old, and there are not a few people who have claimed to have psychic powers, although when it comes to proving it, they have not been able to show it.

Faced with these questions, as surprising as it may seem, there are those who have tried to study them in a scientific, building instruments with the intention of demonstrating if a person was capable of reading his mind to another.

Among these instruments we have the famous Zener charts, some cards in which there are drawings that must be guessed or mentally transmitted to other people. Let's discover the mysterious world of extrasensory investigation with these letters.

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What are Zener cards?

Zener cards are cards or playing cards designed to be used in extrasensory perception or clairvoyance experiments. They were created in the early 1930s by Karl Zener (1903–1964), a psychologist at the perception, and his botanist colleague J.B. Rhine (1895–1980), founder of parapsychology as a branch of psychology. These letters

They are one of the first supposedly “scientific” instruments to objectively study supernatural powers., although its pseudoscientific nature has generated much controversy.

A normal deck of Zener cards consists of 25 cards, 5 for each of the 5 symbols that can be found on them: square (□), circle (○), star (☆), cross (+) and wavy lines (⌇). ⌇⌇). Apparently, these symbols were chosen because they are easy to represent mentally and, for this reason, Zener and Rhine deduced that they were easier to transmit telepathically. Thus, it was considered that these letters were ideal to be able to carry out scientific experiments in which statistical methods typical of true sciences could be applied.

Experimenting with these cards

Testing people's telekinetic and clairvoyant abilities can be done in many different ways, but essentially the method is usually the same. The use of these cards is intended to find out if a person is able to read the mind of another who is looking at the cards. A fairly classic example to demonstrate someone's telekinetic ability is the one we are going to see below.

Two people participate in the experiment as subjects, while an experimenter is recording any phenomena that may occur. during the study. These two people are an "agent" or "sender" and the other is the "perceiver" or "receiver". The idea is that if the perceiver has psychic powers, he will be able to read the agent's mind.

The two persons they are seated at two ends of a table, preferably separated by an opaque partition or screen, since the ideal is to prevent both subjects from seeing each other. The person who will act as an agent will receive a deck of 25 Zener cards, which they will have to pick up one by one. He will look at each card for about 5-10 seconds, trying to think only of what he is seeing. The other person, who is supposedly perceptive, will write down on a piece of paper the symbols that they think they are reading in the agent's mind.

Once the 25 cards in the deck have been uncovered and read, the experimenter will compare in which order the symbols of the Zener deck have been presented and which symbols the perceiver has captured. He will statistically analyze both lists, to see if there has been a case of real telekinesis or if the supposed perceiver lacks any psychic power.

According to the clairvoyant community itself, this experiment should be repeated for several days., at least 5 times. Every day the same experiment will be carried out in which 25 Zener cards are uncovered and it will be checked to what extent the perceiver is capable of mentally reading what the agent sees. Once the coincidences have been analyzed and studied, it will be possible to clarify whether or not there really is extrasensory communication.

As Zener card decks usually have 25 cards, 5 for each of the 5 symbols, in case If you do not have any psychic power, you cannot hit more than 20% of the cards, that is, only 5. In principle, if that percentage of correct cards were to be exceeded, according to the extrasensory experimenters, randomness would be overcome and we would speak of a case of true mind reading.

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Criticism of Zener and Rhine

Although Zener charts are undoubtedly an interesting instrument, their research has been criticized. Both claimed to have found cases of people being able to read other people's minds, but when their same experiments were replicated, this evidence vanished. Even so, the New Age community and other followers of the mystical have considered the "findings" of these two researchers as strong evidence of the existence of psychic powers.

The first criticism of experiments with Zener charts is the fact that there is a risk that the charts will be presented always in the same order, making the perceiver end up learning it unconsciously and, sooner or later, guess the cards. It wouldn't be mind reading or telekinesis, but memorization. It should also be said that Rhine tried to avoid this phenomenon and in his experiments he chose to shuffle the cards with a special machine.

John Sladek, science fiction writer, made known his disbelief in the book The New Apocrypha due to the fact that two supposedly rigorous researchers had opted for the letters as a tool to verify the existence of extrasensory powers. The cards have been used by magicians and gamblers in casinos for a long time, having their own methods to trick them and know, without having to uncover them, what is there in the other side.

In the event that the experiment was carried out without screens or anything that impeded the vision between the two subjects, it may happen that the perceiver end up learning what's behind the card just by seeing a crinkled corner or characteristic pattern of the card on its side without drawing. It may seem far-fetched, but in this same situation the agent person can know what the agent sees not by reading her mind, but her eyes. The pattern you are seeing can be reflected off the cornea, letting the perceiver know which pattern it is.

Finally, we have the case of non-verbal language. If both subjects are seeing each other and know each other a little, are likely to communicate without needing to speak. It is by means of unconscious microexpressions that an agent can indicate to the perceiver whether or not he is guessing the symbol that he is indicating to the experiencer. That is, if the perceiver says "star" and the agent makes a small gesture of displeasure, the perceiver will assume that he has made a mistake and will change his answer.

We have an example of reading microexpressions in the 2016 case investigated by Massimo Polidoro. Polidoro tested a mother and daughter who claimed to have psychic powers, with a success rate of over 90% using the Zener cards. However, the researcher placed restrictions so that they could not see each other's faces, which reduced their success rate to simple chance. Mother and daughter did not cheat, but they knew each other so well that they could unconsciously communicate through small gestures.

What are the chances of hitting the entire deck?

Rigorously scientific evidence that clairvoyance and telekinesis exist is conspicuous by its absence. Zener cards, used in experiments in which the two experimental subjects do not see each other and the deck is highly shuffled, they are a good method to demonstrate just the opposite of what Rhine and Zener wanted, which most likely is that extrasensory powers do not exist, or at least mind reading.

The results of the tests that have been done with these cards follow the normal distribution, with the percentage of success not exceeding 20%, which corresponds, as we have said, to guessing only 5 cards from a deck of 25. About 79% of people will guess between 3 and 7 cards. Guessing more than 5 is possible but statistically unlikely. Let's see below the possibilities of guessing more than that number of cards

The percentage of guessing 8 or more cards correctly is less than 10.9%. The chances of getting 15 answers correct is about 1 in 90,000. Guessing from 20 to 24 has a probability close to 1 in 5,000,000,000 and guessing absolutely all of them. has a 1 in 300,000,000,000,000,000 chance.

Taking into account these possibilities calculated mathematically and that correspond to what was observed in real experiments with Zener charts, what would be expected of any rigorous scientific investigation would be to apply Ockham's razor and accept the null hypothesis for null or negative results. In other words, you can't read the mind of whoever is looking at one of Zener's many letters. However, parapsychology is not a science, much less is it going to use the scientific method itself.

This pseudoscience has invented ad hoc explanations to explain and deny the failure of its investigations, some of them truly various, such as that there are people who have "psychic anti-powers" and reduce the extrasensory abilities of those who do. have. Many parapsychologists say that it is to be expected that 99% of subjects do not have psychic powers, but 1% do and can "prove" it. But the curious thing is that, to this day, they have not proven anything.

Bibliographic references:

• Rhine, J. b. (1934). Extra Sensory Perception. Boston, MA, US: Bruce Humphries.
• Rhine, J. b. (1937). New Frontiers of the Mind. New York, NY, US.
• Mauskopf, S. H., & McVaugh, M. R. (1980). The Elusive Science: Origins of Experimental Psychical Research. Baltimore, ML, US: Johns Hopkins University Press.
• Polidoro, M. (2003). Secrets of the Psychics. Prometheus Books.