Paranormal vs. Artifacts, October 14, 2002
Part Seven
The method of forced choice.
A few years ago, a friend, in good faith, built a kind of “psychic wave cannon”. Together with others, he experimented with this device. One version involved using two coaxial solenoids, one inside the other, through which currents flowed in opposite directions, thereby creating a “zero field”. All this was based on a theory I didn’t fully understand, I admit. One day, enthusiastic and confident, he invited me to be the subject of an experiment. By aiming this “cannon” at my forehead from a few meters away, it was supposed to “stimulate my third eye”.
“Do you feel anything?…” “Well…”
A medium who had undergone these tests a few days earlier reportedly rolled around on the floor; apparently the signal was unbearable for her. After a while, I said to my friend:
“Let’s see whether I feel anything or not. Take a coin. Let’s call one side ‘1’ and the other side ‘2’. Using this primitive device, we’ll create a series of pairs:”
1 – 1 – 2 – 1 – 1 – 2 – 1 – 2 – 2 – 2 – 1 – 2, etc…
“What’s the purpose of this?” “Instead of presenting the stimulus just once and asking whether I perceived it or not, we’ll use a ‘forced choice’ system. You’ll announce a ‘pair of trials’ according to this procedure:”
First trial…… (you wait a few seconds)
Second trial… (you wait a few more seconds)
Based on the sequence of numbers obtained from flipping the coin, you’ll present the stimulus during the first trial and nothing during the second, when the number is 1. Conversely, when the number is 2, you’ll present nothing during the first trial but the stimulus during the second. After presenting this pair of trials, you won’t ask me whether I felt anything; instead, you’ll ask me in which of the two trials the stimulus was present. This puts me in a situation of “forced choice.” I won’t be able to avoid answering. And even if I feel like I didn’t perceive anything in either trial, you’ll still demand an answer from me, whatever it may be.
“And then?” “Afterwards, you’ll count the correct responses. If I truly perceive something clearly, the percentage will be high. And if I perceive nothing, it’ll be zero?” “No, it’ll be fifty percent. Depending on the intensity of the stimulus, the percentage of correct responses increases, provided the subject actually perceives something. In experimental psychology, this is a classic way of detecting subliminal perception—visual, auditory, tactile. For visual perception, a subject is placed in a completely dark room; then a very faint light signal is presented. Each time, the subject must respond. The same protocol applies in a soundproof room with an auditory signal. What’s interesting is that it’s possible to achieve a response rate significantly higher than 50% (there are mathematical methods to assess how “significant” a positive response is), even though it seems like the subject perceives nothing at all and merely responds randomly during each pair of trials.”
All this corresponds to what’s known as “signal theory.” Assuming that the lack of perception is due to the signal being drowned out by “Gaussian background noise,” the theoretical curve above takes the form of what’s called a sigmoid curve (a simple exercise for beginners).
We proceeded as I suggested; my percentage of correct responses was 52%. This wasn’t statistically significant. Thus, my “third eye” was completely insensitive to those psychic waves. Things got complicated when he himself became a subject; his performance turned out to be comparable to mine. Since this “psychic wave cannon” cost quite a few million old francs, I left… on tiptoes. I won’t mention those situations where simply introducing some methodology into an experiment ended up in disaster.
Final note: To eliminate any artifacts, it would be better to have a computer control the experiment (which would regulate timing and display messages on a screen) rather than a human operator. After all, it’s easy for an operator to indicate to the subject where the stimulus is located by changing their voice pitch or volume, gestures (if visible), or simply by varying the duration of each manipulation. Moreover, between an experimenter and their subject, unconscious complicity can develop, despite everyone acting in good faith. As we all know, hell is paved with good intentions.
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