The Ganzfeld Experiments: Quality – Conclusion

Previously, I assessed the quality of evidence provided by the ganzfeld experiments. I found that the typical ganzfeld experiment could only be considered to yield Moderate evidence, and further that it was necessary to downgrade the entire body of studies at least once, for heterogeneity.
That leaves the overall quality of evidence for the ganzfeld trials as Low. There is no way that I could justify any higher grade but one could certainly justify a lower one. One could justify a double downgrade for the heterogeneity, on account of the serious implications. One could also justify downgrading for publication bias. And then, I didn’t look in detail at the individual studies, which could only uncover reasons for downgrading, as I found that there was no reason to upgrade.
When two (or more) factors are borderline, one should downgrade for at least one.

Put like that, calling the evidence of Low Quality is a very favorable assessment.

The best argument for a better grade is claiming that the ganzfeld design as it is should be regarded as High Quality, like a medical RCT. I’ve already laid out why I don’t agree with that. It would simply lead to another borderline case and at some point you can’t ignore all these borderline calls and must downgrade for at least one of them.

But what does that mean?

Quality level Current definition
High We are very confident that the true effect lies close to that of the estimate of the effect
Moderate We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different
Low Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect
Very low We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

Note well what this does not mean. It does not mean that there is no effect. It means that we can have no confidence that there is one. But equally it means that we can have no confidence that there is none.

And that simply means that everyone will retain whatever opinion they had beforehand which leads us to another curious feature of parapsychology in general.
Parapsychologists say that the hit-rate should be 25%. Any conventional cause for a deviation is not of interest and should be regarded as a bias. The basic ganzfeld design has been intensely scrutinized for any such potential bias and modified to rule it out.
This puts parapsychologists into the position to make a solid and credible argument that the hit-rate must be 25% by any conventional expectation. And it is that which lends credence to the argument that any systematic deviation, any effect, must be due to something amazing, that some worthwhile scientific discovery is waiting there.

Unfortunately, the sheer solidity of the theoretical argument means that few mainstream scientists will be swayed by low quality evidence. Curiously, many vocal parapsychologists seem unable to understand this.
They accuse mainstream science of being “dogmatic” and yet the failure to convince the mainstream with low quality evidence is precisely because of the solidity of their arguments that, by all prior evidence, the hit-rate must be 25%.

  1. Parapsychologists work hard and convince people that the hit-rate should be 25%.
  2. Parapsychologists accuse people of being dogmatic for believing it.

It’s one of those things about parapsychology that does not make the slightest bit of sense. Such displays of irrationality are ultimately responsible for parapsychology’s bad reputation. Low quality evidence is normal enough. That’s why there is such a thing as the GRADE approach.
If someone appears irrational, you probably won’t attempt a rational dialogue. And if you try anyway and your open-mindedness is rewarded with accusations of dogmatism and even dishonesty, then your probably give up.
It is that which leads mainstream science to, for the most part, shun parapsychology. Which then leads prominent parapsychologists to double down and declare that there is a “taboo” against dealing with them. But that’s a different matter.

Does GRADE work?

That’s a very good question. I hope it occurred to you.

One thing we would like to know is how reliable the assessment is. How much agreement is there between different raters? And the answer is: Not as much as we’d like. There is human judgement involved in the rating which is one reason that the GRADE approach demands transparency.
I have tried my best to make the reasoning as clear as possible and have already discussed where others might differ in their assessment.

The other thing we would like to know is how solid the conclusion is. Say, you have 1,000 different apparent effects but based on evidence rated Low or Very Low. How many of those effects would really be found to be substantially different?
The answer: No one knows, yet.

In relation to the ganzfeld, however, we can say that the assessment would have been exactly spot on. I’ve talked about a 33% hit-rate because that is often claimed but, in truth, the hit-rate has varied wildly. When some of the earliest experiments were analyzed in 1985, a hit-rate of 37% was obtained; while when studies from between 1987 and 1997 were analyzed a hit-rate of only 27% was obtained.
In the latter case it was, of course, the parapsychologists who were not impressed and argued that this was due to certain specific biases. That’s something for a later post.


So eventually we find that the ganzfeld evidence is of Low Quality but that should not come as a surprise to anyone.
The more important lesson is probably that this is so according to the standards of mainstream medical science. Other sciences may have a lower standard; I’m thinking of psychology in particular. Indeed, it has been asserted by psychologist Richard Wiseman that the ganzfeld is solid by the standards of his field but, as far as I can tell, his colleagues are, on the whole, not particularly impressed which would seem to contradict his assessment.
In any case, accusations of a double standard clearly lack merit.

What I find more worrying are the problems that parapsychology has in interpreting the evidence and drawing supportable conclusions, regardless of quality considerations. Low Quality evidence is not unusual, but the irrationality surrounding the whole issue is.

What If: High Quality Evidence ?

I think many parapsychologists have very unrealistic expectations about that. Remember that all that could be concluded from the ganzfeld experiments is the presence of some unexplained effect causing the chance expectation to be wrong.
High quality ganzfeld evidence would just indicate that there is probably something worth studying there. Some scientists would become interested enough to look into it. Most would simply be too busy with whatever they are already doing.
The interested scientists would then start out by repeating the original, standard ganzfeld experiment to create the effect in their own lab. And then, once they have succeeded in that they would study the effect. If the found themselves unable to recreate the effect, they would still give up. If you can’t create an effect, you can’t study it, even if you are convinced it exists.
And that’s all that would happen.

The situation currently, with low quality evidence, is not fundamentally different! It just means that fewer people are going to think they can recreate the effect or that the effect is due to something worthwhile.
This idea that high quality evidence for psi would lead to some sort of “paradigm shift” because of some single experiment is just nonsense. That kind of thing has never happened before and I don’t see how it could happen even in principle.

While this concludes the GRADE business, this does not conclude the quality series. There are some more issues we need to talk about, such as what parapsychologists had to say about all this.

Examples of mishaps

I want to give some examples of things that actually went wrong in the ganzfeld experiments. I hope it may illustrate how these vague biases may look “on the ground”.
Do not take these examples as a reason to dismiss the experiments. You can take the Low Quality as a reason for that but these examples are just, you know, life. Things don’t go perfect.
Parapsychology doesn’t stand apart in that respect.

These results differ slightly from those reported earlier since an independent check of our database by Ulla Böwadt found an extra hit in study V. Two trials in study IV (a hit and a miss) had also been included although the experimenters apparently were not agreed on this prior to the results. Their exclusion would make however virtually no effect on the final figures.
A review of the ganzfeld work at Gothenburg University by Adrian Parker, 2000

This shows how individual trials may simply fall through the cracks. It would have been completely justifiable not to include those. One has to wonder if the media demonstration, in particular, was conducted with the same diligence as the regular trials.
Somewhat similar problems are known in medicine. In a medical studies, patient may drop out; they quit the experiment. One must suspect that it will usually be those who are disillusioned by the offered treatment, or, perhaps, those who see no need to continue because the feel cured. In either case, this will bias the results. This so-called attrition is considered by GRADE.
Another thing this is similar to is transcription errors. You probably won’t be surprised to learn that people have actually been maimed and killed because of doctors’ illegible hand-writing but it’s also a problem in science. Bias may be introduced into a study simply because of faulty data entry. That published values had to be corrected has happened on occasion in ganzfeld experiments and particularly meta-analyses.


An amusing, recent example is an analysis published in 2010: Meta-analysis of free-response studies, 1992-2008: assessing the noise reduction model in parapsychology by Storm L, Tressoldi PE, Di Risio L.
The article is more full of errors than I care to point out but this is just about one of them (one of the less embarassing ones).
As part of their analysis they rated the ganzfeld experiments for quality. What they did wrong there is for a later post. The details of the rating were obtained by a couple of scientists, Jeffrey N. Rouder, Richard D. Morey and Jordan M. Province. They argued that improper randomization could explain a part of the results. More on that later.
One of the counter-arguments by the original authors was that the ratings, obtained from them, contained errors!


After about 80% of the sessions were completed, it was becoming clear that our hypothesis concerning the superiority of dynamic targets over static targets was receiving substantial confirmation. Because dynamic targets contain auditory as well as visual information, we conducted a supplementary test to assess the possibility of auditory leakage from the VCR soundtrack to R. With the VCR audio set to normal amplification, no auditory signal could be detected through R’s headphones, with or without white noise. When an external amplifier was added between the VCR and R’s headphones and with the white noise turned completely off, the soundtrack could sometimes be faintly detected.
Psi Communication in the ganzfeld: experiments with an automated testing system and a comparison with a meta-analysis of earlier studies by Honorton et al, 1990

This means that the receiver(R) may have heard the sound of the correct target, which certainly would have allowed him or her to make the correct guess. That’s potentially serious. The counter-argument, however, sounds quite convincing, as well: There was no drop in the hit-rate after the sound system was modified to rule that out.

That’s certainly quite suggestive but mind that it is not high quality evidence. We have a bunch of trials conducted before the sound system was fixed and a bunch afterwards but there is no direct, randomizzed comparison.
And what does the unchanging hit-rate indicate anyway? Maybe they just failed to remove the problem with the modification.

For what it’s worth, when that lab closed the equipment was moved elsewhere where it was used by different experimenters. They were unable recreate the effect.
You could take that as evidence that maybe the sound system played a role but once again: Low quality evidence. There certainly were other documented potential biases in the experiments at that lab which may not have been present at the new location.

[sound of sighing]

The May issue of The Psychologist carries an article by Stuart Ritchie, Richard Wiseman and Chris French titled Replication, Replication, Replication plus some reactions to it. The Psychologist is the official monthly publication of The British Psychological Society. And the article is, of course, about the problems the 3 skeptics had in getting their failed replications published.

Yes, replication is important

That the importance of replications receives attention is good, of course. Depositories for failed experiments are important and have the potential to aid the scientific enterprise.

What is sad, however, is that the importance of proper methodology is largely overlooked. Even the 3 skeptics who should know all about the dangers of data-dredging cavalierly dismiss the issue with these words:

While many of these methodological problems are worrying, we don’t think any of them completely undermine what appears to be an impressive dataset.

But replication is still not the answer

I have written about how replication cannot be the whole answer before. In a nutshell, by cunning abuse of statistical methods it is possible to give any mundane and boring result the impression of showing some amazing, unheard of effect. That takes hardly any extra work but experimentally debunking the supposed effect is a huge effort. It takes more searching to be sure that something is not there than to simply find it. For statistical reasons, an experiment needs more subjects to “prove” the absence of an effect with the same confidence as finding it.
But there’s also that there might be some difference between the original experiment and the replication that explain the lack of effect. In this case it was claimed that maybe the 3 failed because they did not believe in the effect. It takes just seconds to make such a claim. Disproving it requires finding a “believer” who will again run an experiment with more subjects that the original.

Quoth the 3 skeptics:

Most obviously, we have only attempted to replicate one of Bem’s nine experiments; much work is yet to be done.

It should be blindingly obvious that science just can’t work like that.

There are a few voices that take a more sensible approach. Daniel Bor writes a little of how neuroimaging which has, or had, extreme problems with useless statistics might improve by foster greater expertise among the practitioners. Neuroimaging seems to have made methodological improvements. What social psychology needs is a drink of the same cup.

The difficulty of publishing and the crying of rivers

On the whole, I find the article by the 3 skeptics to be little more than a whine about how difficult it is to get published, hardly an unusual experience. The first journal refused because they don’t publish replications.
Top journals are supposed to make sure that the results they publish are worthwhile. Showing that people can see into the future is amazing, not being able to show that is not. Back in the day it was simply so that there was only a limited number of pages that could be stuffed into an issue, these days, with online publishing, there’s still the limited attention of readers.
The second journal refused to publish because one of the peer-reviewers, who happened to be Daryl Bem, requested further experiments to be done. That’s a perfectly normal thing and it’s also normal that researchers should be annoyed by what they see as a frivolous request.
In this case, one more experiment should have made sure that the failure to replicate wasn’t due to the beliefs of the experimenters. The original results published by Bem were almost certainly not due to chance. Looking for a reason for the different results is good science.

I’ve given a simple explanation for the obvious reason here. If the 3 skeptics are unwilling or unable to actually give such an explanation they are hardly in a position to complain.

Beware the literature

As a general rule, failed experiments have a harder time to get published than successful ones. That’s something of a problem because it means that information about what doesn’t work is lost to the larger community. When there is an interesting result in the older literature that seems not to have been followed up on then it probably is the case that it didn’t work after all. The original report was a fluke and the “debunking” was never much published. Of course, one can’t be sure if it was not maybe overlooked, which is a problem.
One must be aware that the scientific literature is not a complete record of all available scientific information. Failures will mostly live on in the memory of professors and will still be available to their ‘apprentices’ but it would be much more desirable if the information could be made available to all. With the internet, this possibility now exists and that discussion about such means is probably the most valuable result of the Bem affair so far.