5X5 Episode 86
|5X5 Episode 86|
|21st February 2010|
|5X5 85||5X5 87|
|S: Steven Novella|
|B: Bob Novella|
|J: Jay Novella|
|E: Evan Bernstein|
|M: Mike Lacelle|
You're listening to the Skeptics' Guide 5x5, five minutes with five skeptics, with Steve, Jay, Rebecca, Bob and Evan.
S: This is the SGU 5x5 and tonight we are talking about parapsychology or psi.
E: It was back in 1927; Professor of psychology Joseph Banks Rhine attended a lecture at his place of employment, Duke University in Durham, North Carolina. The lecturer that night was Sir Arthur Conan Doyle, who was the infamous author of the famed literary character Sherlock Holmes. And the subject of Doyle's lecture that night was on the scientific proof of communication with the dead. So impressed was Dr. Rhine with that lecture that he began in earnest the scientific pursuit of what he termed "abnormal psychology" or parapsychology. Hence, the modern parapsychology movement had officially begun. Through his utilisation of Zener cards—that's the deck with five different distinct drawings that his subjects were asked to guess the correct card using only the power of their minds, Dr. Rhine engaged in 5 years worth of tests in a quest to uncover the scientific evidence of psychic abilities, culminating in his book published in 1934 titled Extrasensory perception or more commonly referred to as ESP.
S: ESP is just one type of psi, which is spelled P-S-I and is an abbreviation of parapsychology. This includes any paranormal mental activity such as reading minds, predicting the future, remote viewing—being able to see a remote location just with your mind, for example. Since Rhine, parapsychology or psi research has continued, although in the last 80 years, psi research has been unable to produce a single, reproducible laboratory phenomenon demonstrating that psi exists.
B: Psi tests using shuffled Zener cards usually consisted of a sender looking at one card at a time while another person, the receiver, tried to telepathically receive the image of the card. Another common method involved simply one test subject guessing what the top card on the deck was without anyone else looking at it. Since there were 5 different cards, there is a 20% chance of guessing the correct card, assuming no feedback was coming from the sender. Therefore, large trials of many hundreds or maybe even thousands of cards resulting in a hit rate significantly higher than chance most often requires an explanation other than chance. Some conclude psi must be the cause. Skeptics generally, of course, need to have other factors ruled out, like experimental design or perhaps even cheating.
M: So, is there cheating involved? Well, we do know that in early experiments, Rhine used decks of Zener cards that were printed on very thin and translucent paper. This allowed test subjects to see through the card to identify the symbol. There is a lot of criticism towards Rhine's test methods and once he changed his methods to be more rigorous, he wasn't able to find any high-scoring test subjects to match his early successes. When he used a magician to observe E. Pearce Junior, one of his highest-testing subjects, Pearce's performance sunk back to chance levels. When not observed, his scores were significantly higher.
J: Also, the fact that the Zener card deck only contains 25 cards, in which each card is discarded after use, makes the chances less random than guessing. For example, in a full deck of Zener, the statistical chance of guess one card correctly is 1 in 5. However, once you remove that card the chances become slightly higher because the deck now only contains 24 cards, and so on. And the use of the Zener card deck is not truly random. For example, there are only five instances in each deck that each symbol is represented. So runs of 6 identical symbols are impossible. In a truly random deck, such runs would be possible.
S: So this represents the classic error, if you will, of psi research and they made a number of what are now classic experimental mistakes. They all essentially amount to ways of cherry-picking the data or only picking some subset of the data. One example of that is so-called "psi missing" in which the guesser, the person who is supposed to be psychically guessing what the target cards were, would miss more often than chance. However, if you look at the multiple different ways in which the result could deviate from chance, such as guessing correctly more often than would be predicted by chance or guessing incorrectly more often than would be predicted by chance, you're essentially doubling your chances of a random result deviating from chance. And if you don't take that into account with the statistics, you can get falsely positive results. Another example was called "optional starting and stopping". You may do hundreds and hundreds of trials, but decide that there's a warm up period—a random warm up period in which the person being tested may suddenly start to guess correctly more often than chance and then that run will suddenly stop—again, unpredictably. This was interpreted as, again, a period where the subject was guessing psychically more greater than chance but, again, what that really amounts to a way sifting through large amounts of data, picking up random runs where the subject performed better than chance and then cherry-picking that subset of the data. Essentially, you're not allowed to do that in research. You have to count all data points continuously. Otherwise, it's not a truly random selection. So, therefore, these became classic examples of how to manipulate data in research. Psi researchers are no longer making these basic mistakes, but as we will see in future installments of 5x5, psi research has become more sophisticated, but even still, they are still unable to generate consistently positive results.
S: SGU 5x5 is a companion podcast to the Skeptics' Guide to the Universe, a weekly science podcast brought to you by the New England Skeptical Society in association with skepchick.org. For more information on this and other episodes, visit our website at www.theskepticsguide.org. Music is provided by Jake Wilson.