How Can You Tell If You Have ESP?

Since this is typically the slowest week of the year—even Christmas is busier—this is a good time to introduce something strange. About twenty years ago I wrote a skeptical (do not forget this word) book about parapsychology. The best way to teach skepticism is by doing, so the book is a compilation of ESP-like experiments anybody can do.

The idea is simple: discuss what the purported ability is, give several tests for it, and then show all the things that can go wrong with the tests, thus seeing how easy it is for mundane effects to be mistaken for paranormal abilities. I teach probability, experimentation, evidence, and all that as we go along. All valuable skills for judging any science. And parapsychology is a science. Though not, I think, a good one.

Skepticism is not dismissivism. Even though, as I believe, the experiments I have seen in the past have failed in one way or another, it could be that they were flawed in some way that can be overcome. Claims must be tested. The chief flaw in old experiments are the supposed mechanisms touted for ESP, in which the word vague is a vast understatement. I believe there is a spiritual non-material side to our natures, which means extra-normal communication between people is a possibility (between God and us it is a certainty). Yet it is far from clear just what weight communication carries here.

I wrote So, You Think You’re Psychic? (free in PDF form on my site) ten full years before Uncertainty (on which we do the Class), a time in which my views on probability had not coalesced. A nice way to say they were wrong. Indeed, I then used language which I now firmly reject. Since I cannot bear this, I must update the book to do the probability properly. There are many new avenues worth exploring since 2006, too, like Rupert Sheldrake’s staring experiments.

What I’d like are ideas readers have on a book like this. I’ve never liked the title, but then I am (as you know) the world’s worst title writer. How about a Hollywood-like sequel So, You Still Think You’re Psychic? Below is a typical homebrew experiment (and the first). How does the format grab you? This comes after two chapters discussing parapsychology in general, experiments in science, coincidences, etc., and how to interpret probability scores. Which I am changing. This table is new. The except cuts off before the WHAT CAN GO WRONG? which is included with every experiment. (Here, feedback is the biggie.)

I’d be especially interested in anybody out there who tries the experiment.

Onto the excerpt!

Telepathy

Telepathy: The ability to gather information about someone else’s thoughts through non-verbal, non-sensory means. Sometimes known as mind-reading or extra-sensory perception (ESP).

Quick—I’m thinking of a number between one and five! Can you read my mind? Was your guess three? That’s the most common guess. And if your guess matched my number maybe you have telepathy. Or maybe not. To convince me you had extraordinary powers, it would depend on how difficult, and how surprising, your guess was. If my number was three your hit is not necessarily that surprising because you could have guessed correctly by luck.

The number I was thinking of was e. That’s equal to about 2.71828. What? You’ve never heard of this weird number e and you think I was cheating? Well, I never said my number had to be an integer; that is, a whole number like one, two, three, four, or five. I specified a number between one and five and e=2.71828 is certainly in that range.

But maybe you did guess correctly; even so, I wouldn’t be terribly surprised. Why? Because you might have known I was mathematically minded, guessed I was being tricky, and figured I would use an extremely common number mathematicians encounter daily. Another number might have been $\pi$ (which is about 3.14159). There are lots of mathematically common numbers between one and five, and there are an uncountably infinite selection of other numbers, which it is why it is necessary to set up an experiment, in advance, that allows me to quantify the chances of you and I thinking of the same one merely by luck. Controlled experiment are needed in which the only thing that is left to chance is the guessing (or mind reading) itself.

The end of this experiment, where you guessed my number between one and five, is the first example of a multiple endpoint; multiple endpoints were described in Chapter 2 [on probability]. The test, when I first announced it with a “Quick!” was not completely defined because I never specified the set of possible answers you could choose from. You were free to make any guess you wanted, whether an integer or some strange number and then, after the fact, when I revealed my number, transform your score to something that seemed surprising by arbitrarily defining your choice of possible answers. For example, you first might have thought that the possible answers were the numbers one through five. If you were to say the set of answers included all real numbers, the chance of you guessing my exact number by chance would be exactly 0 (Chapter 2 explains why this is true). That’s as surprising as you can get and potential evidence of psi. On the other hand, I could retort that I limited my choice to e and $\pi$, which means a no-skill match happens half the time, thus a correct guess is not in the least surprising. This is why only controlled experiments with fixed endpoints are convincing.

Of all paranormal abilities it is probably telepathy (sometimes given the important sounding academic title anomalous information transfer) that most excites the imagination, engenders the highest interest, and generates the most enthusiasm. Almost everyone feels they have had some personal experience with various forms of telepathy, whether it’s picking up the phone just as someone calls, or thinking the same thought at the same moment as the person you are with. It is the ability that, even if you suspect other psi claims to be false, you are sure to think there is some truth to this one. Parapsychologists think so too and more experiments have been done in this area than any other.

Casual instances of telepathy are common. Imagine you and your sister are together, chatting over coffee about the hair dresser, about the bad hair style your mutual friend Edith affects to wear in public and so on, and then you have a flash, “Say, Judy, I was just thinking of that time when Bob chopped off half his moustache.” Judy says, “Me too! Isn’t that extraordinary! I must have been reading your mind!”

Not necessarily.

It may be the case that the more time you spend with someone the more it’s likely you will begin to think alike (maybe even to a degree look alike) and share the same thoughts. The more time together the higher the chances become that, if you want to think biologically, your brain’s neurons fire along identical pathways, using as input similar circumstances and shared sensory experiences, your minds arriving at nearly identical conclusions. Your common history and education, mutual background, and communal social activities help you interpret the world around you in a similar manner. It would be more surprising for two people like this—a married couple, for example—not to be thinking of the same things at the same times for a lot of their life. So how surprising is it that you and someone you know very well both happen to be thinking of the same thing? And how can you quantify the correspondence of thoughts? These tests can help answer that question.

Test Number One: The Card Test

This is a very easy and clean test. It is also very traditional in that the first formal tests of telepathy were very much like this. The materials needed are a deck of cards and your notebook. The set up is simple and quick. Cards are used because most people have at least passing familiarity with their shapes and values: this acquaintance is thought to ease mental transmission. The only difficulty may be in securing the help of a friend—but who doesn’t want to learn if they are telepathic? The next time you have a party you can assemble people into groups of two and run the test concurrently for each group.

WHAT YOU WILL NEED

• A deck of new clean playing cards (poker or bridge), or a deck of Tarot cards.
• At least one friend.
• Your notebook with two ruled columns (these can be done by hand). One column is headed Card and the next Guess.
• (Optional) A watch with a second hand.

WHAT YOU WILL DO

Details will be given for an ordinary deck of playing cards. Tarot cards will work but you must first remove the cards of the Greater Arcana (Death and all his brothers) and the Knaves of each suit (pentacles, swords, etc). Only 52 cards can remain in the deck for the probability score to be valid.

• Be sure to first remove all jokers from the deck of playing. Only 52 cards should remain.
• Riffle shuffle the cards at least seven times to insure they are thoroughly mixed. Riffle shuffling is the type where you take approximately half the cards in each hand, held lengthwise, and both piles are flipped towards each other to mix them. Square the deck when this is done. Straighten them out so they are all in one neat pack. For those who are interested, it was mathematically proven that cards should be shuffled at least seven times to attain “true randomness” (meaning the order is essentially unpredictable to you), so do not be lazy here.
• Decide who will be the sender and who will be the receiver. You can certainly swap roles in subsequent tests.
• The sender picks up the first card from the deck and notes it down in the Card column of the notebook. Shorthand should be used. Suppose the first card was the Queen of Spades: QS would be written. Use D for diamond, C for clubs, H for hearts, and S for spades.
• The sender then concentrates on the card for a prescribed amount of time (say 30 seconds) during or immediately after which the receiver states her impression of the card.
• The sender then writes this impression in the Guess column next to the Card column.
• Card number two is selected and the test repeated, and so on.
• After all cards are expended the sender then tallies the results by circling the matching results. The number correct is compared with the Telepathy Card Scoring Table for the score.

[This next part is where I go wrong, because what we really want is the probability the power is real, and not the probability of the data assuming there is no power, which is a nasty p-value notion.]

Telepathy card scoring table. This table shows the probability of getting $n$ or greater correct matching cards from a deck of 52. Only correct guesses up to 6 are indicated, as it would be highly unlikely to get 7 or more correct. As it is, there is strong telepathic evidence by getting only 4 or more matches—the probability of this happening by chance is only 0.019 (this means it would happen by chance about 2 times for every 100 trials). [There is no such thing as “by chance”, and only an idiot like me would write there is. I am fixing all this. The Table does look pretty in the book, though; here I am too lazy to HTML it.]

Probability of Getting at least $n$ Correct Cards:

n = 0: p = 1
n = 1; p = 0.64
n = 2; p = 0.26
n = 3; p = 0.08
n = 4; p = 0.018
n = 5; p = 0.0032
n = 6; p = 0.0005

This is only one possible scoring table because the guessing strategy used by the receiver can modify the probability results. A quick example will show how. Imagine the receiver always said Three of Clubs for each guess. Then she must get at least one guess correct, this being the time when the card was the Three of Clubs. All other cards will be wrong (of course). The makes the probability of getting 1 or more correct matches 1, and forces the probability of getting 2 or 3 etc. or more correct matches to equal 0. This table assumes the receiver is guessing freely, each time making a selection from any of the 52 possible cards, and the receiver may guess the same card more than once if she likes.

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