Discussions of parapsychological experiments usually focus on the quality of the alleged evidence. I will break with this tradition and begin by analyzing what conclusions are warranted if the results are as parapsychologists claim. Let’s begin by looking at the typical Ganzfeld experiment.
The typical Ganzfeld experiment
We have two experimental subjects or participants. One is called “sender” and the other “receiver”.
The sender is shown a video clip or a still image (in one case music) which was randomly selected from a collection. He or she is supposed to watch or listen to this for around 20 minutes while the receive” is “in the Ganzfeld”, that is, he or she experiences a mild state of sensory deprivation. During this time the receiver just says whatever goes through their mind and this is recorded.
Afterwards comes the judging procedure. The target is presented along with 3 decoys (though occasionally a different number was used) from the same collection of possible targets. Sometimes the judging is done by the receivers themselves, possibly with the help of an experimenter, and sometimes by an experimenter. Naturally, we are assured that the experimenters involved in the judging do not know the correct answer themselves.
Who is being tested?
That the receiver does not give the answer alone provides an immediate problem in interpreting the result. We cannot know if any correct answer was truly given by the test subject, or by someone else.
One might correctly point out that the only thing that matters is if something paranormal happens. So what if the telepathy is between the sender and the experimenter rather than the designated receiver?
Unfortunately, there are practical implications to this. It is not enough to ensure that the receiver had no way of knowing the correct answer, one must ensure this for the judges, and/or helper as well, which multiplies the problem.
Consider a situation where something like distance-dependence is to be investigated. Not only must sender and receiver be separated by the prescribed distance but also sender and judge and any judging helpers.
Evidence for telepathy?
The conclusion, or rather explanation, offered by parapsychologists is implied in the terminology. The sender sends and the receiver receives in some unknown way simply called telepathy. The catch is that there is absolutely no evidence that the sender actually does any sending.
Yes, if there was some unidentified form of human communication not blocked by whatever separates the two, then that could explain the results. However, the results could also be explained by, just for example, remote viewing.
Some will now say that it doesn’t matter if we are dealing with remote viewing or telepathy, as long as we are dealing with something inexplicable. In the sense that both would be extremely interesting, that is certainly true.
However, it does not change the fact that drawing unwarranted conclusions is simply bad science. Surely, if you have something interesting on your hands you want to do good science on it. Does it really make sense to say: “It doesn’t matter that we are misrepresenting the results, only that they are interesting?”
There are also practical considerations. If it turns out that a sender is not necessary, then you need only half as many test subjects and, on top of that, can schedule the sessions easier.
Finally, I need to be blunt. If someone is unable or unwilling to correctly interpret evidence, then one can’t help but wonder if they are able to correctly implement the experimental protocol. If they tell me that this “proves” telepathy and I see it does not, can I trust them when they tell me that they ruled out all conventional explanations?
A few experiments have been conducted that modified that standard experiment to properly test for the influence of the sender. Discussion of that will need to wait for later.
Many parapsychologists think of themselves as conducting consciousness research. Somehow, in some unknown way, consciousness is thought to be responsible for the Ganzfeld results. Whether we are dealing with telepathy or remote viewing, it must surely be a psychic ability, or so some say.
But again, this does not follow from the data. We have a number of known sensory organs which are clearly responsible for gathering most, if not all, of the information we have about the world. If there was an additional extra-sensory means of perception, there is no reason to assume from the get-go that it would be fundamentally different from the known means. We can only say that it must be much less effective than the known means or we would all be aware of it.
Not only is there no good reason to think that the psyche or consciousness should have anything to do with the results, there is a strong argument against that. The receiver is typically not aware of receiving any information. He or she simply babbles out whatever goes through their mind. Afterwards they will be provided with some record of their babblings and possibly even with help in matching them to the target. In other words, the process is completely unconscious.
Evidence for psi?
Here it gets more tricky, as there is no single definition of psi accepted by all parapsychologists. The Parapsychological Association (PA) says on its web-page:
A general blanket term, proposed by B. P. Wiesner and seconded by R. H. Thouless (1942), and used either as a noun or adjective to identify paranormal processes and paranormal causation; the two main categories of psi are psi-gamma (paranormal cognition; extrasensory perception) and psi-kappa (paranormal action; psychokinesis), although the purpose of the term “psi” is to suggest that they might simply be different aspects of a single process, rather than distinct and essentially different processes.
Obviously, the idea that all alleged psi phenomena are connected cannot, in principle, receive any support from the standard Ganzfeld experiment. And even more obviously, it cannot provide evidence for any other psi phenomenon.
Nothing about the experiment allows any conclusion about the mechanism.
One might say, that, if parapsychologists stumbled across something with one experiment, it would be worthwhile to look at what else they have. That is a reasonable argument, but it is entirely based on social considerations, namely an assessment of how credible parapsychologists are as a group. It does not follow from the experiment.
Another definition, given in some Ganzfeld papers (those by Daryl Bem) goes like so:
The term psi denotes anomalous processes of information or energy transfer, processes such as telepathy or other forms of extrasensory perception that are currently unexplained in terms of known physical or biological mechanisms. The term is purely descriptive: It neither implies that such anomalous phenomena are paranormal nor connotes anything about their underlying mechanisms.
Clearly, this second definition is in direct contradiction to the one by the PA. Not only does the PA explicitly say that psi denotes something paranormal (whatever that means), it also says that it does imply something about the mechanism: Namely that there is a single process for all alleged psi phenomena.
An amusing consequence of the second definition is that psi definitely exists. Whenever someone knows something and you don’t know how, that’s psi.
By that definition, the Ganzfeld experiment can provide evidence for psi but it is not clear why you would even bother. By that definition, the existence of psi is a necessary consequence of us not being all-knowing.
Many psi believers feel that psi is this awesome spiritual thing. If people could be convinced of its existence it would revolutionize all of science, from physics to psychology, and even all of society. That’s not something a single experiment can ever provide.
What it is not evidence for
There is any number of people who claim psychic powers. Some of them do so on a professional basis, that is they charge money for psychic readings. Some people might say that if something is happening in these Ganzfeld experiments then that supports that there might be something to that. Unfortunately, it’s the other way around.
It’s like saying that, because anyone can leap over a low fence, therefore some people might be able to leap over a tall building. That doesn’t follow, of course. No matter how many people you watch jumping a low fence, it will not change the fact that no one can jump over the average building. Even worse, the longer you go on, the clearer it will become that it is simply not possible.
It is much easier to demonstrate an amazing ability, with big effects on the world, than a tiny one. If someone claims the Ganzfeld experiments as “the best evidence for psi” that is basically a tacit admission that psychic powers as portrayed on TV, or the New Age literature, do no exist.
Evidence for what?
Eventually, the standard Ganzfeld experiment can only provide us with evidence that something unexpected happens in such Ganzfeld experiments and nothing else. By design the experiment does not provide us with any clues as to what is going on.
This is the fundamental problem in the standard Ganzfeld design.
We think that the hit rate in a typical Ganzfeld experiment should be 25% but there is any number of reasons why this might be wrong.
Early on, a few possibilities were raised. For example, when a sender is given a photograph, they might leave fingerprints, kinks, scratches or other such clues on the paper. These so-called handling cues might enable the receiver to tell that photograph from other, fresh photographs supplied as decoys.
Such things are usually referred to as flaws in the protocol. I, personally, don’t think it is constructive to label some explanations as somehow inherently reflecting badly on the experimenters. In my opinion, the single flaw is that the design does not allow any conclusions about the explanation, not that it allows for boring explanations.
Parapsychologists frequently point out a catch with such proposed explanations: There is no evidence that they are true. The experiment, after all, only tells us that there is something to be explained, not how.
Unfortunately, they rarely realize that the same is doubly true for their suggestions. As vague as the term is, there is no evidence that something like telepathy exists, so invoking it to explain the Ganzfeld results is simply building on air. Arguing that the Ganzfeld results themselves are evidence for telepathy is simply circular reasoning. One might equally claim the results as evidence for fraud, error, or gremlins.