The Ganzfeld Experiments

[amherst]

What game? I quoted from the Bierman et al. paper you cited above : "A conservative correction [...] reduces the 10% differential effect to a non-significant 6.8%" ("Non-significant," in this context, means that there is not enough evidence to believe the effect could not have come from chance.) This has nothing to with Ersby, as I haven't read the Ersby paper, and don't intend to as I have other demands on my time.

This is part of the scientific process, performing a close examination of the claims and the evidence that support it. Have you read the Ersby paper? What justification does he give for his counterintuitive statement? Is he referring to a specific experiment, to a group of experiments, or to the experimental setup as a whole? What is wrong with his justification?

But statistics is a fairly exact science, and statisticians are usually very good about being explicit about their assumptions and reasoning. If you can't point to what is wrong except a dislike of Ersby's conclusion, that's not very credible. Especially since you've admitted upthread that your mathematical understanding is weak. Why should I trust your opinon when it conflicts with the experts'?

You've greatly misread the paper. The quote "A conservative correction [...] reduces the 10% differential effect to a non-significant 6.8%", was refering to the difference in success betwen Static and Dynamic targets, not the overall sucess of the experiments. The adjusted chance baseline of 25% to .2598 in no way makes the results non-significant.

amherst

 

[Interesting Ian]

What game? I quoted from the Bierman et al. paper you cited above : "A conservative correction [...] reduces the 10% differential effect to a non-significant 6.8%" ("Non-significant," in this context, means that there is not enough evidence to believe the effect could not have come from chance.) This has nothing to with Ersby, as I haven't read the Ersby paper, and don't intend to as I have other demands on my time.

This is part of the scientific process, performing a close examination of the claims and the evidence that support it. Have you read the Ersby paper? What justification does he give for his counterintuitive statement? Is he referring to a specific experiment, to a group of experiments, or to the experimental setup as a whole? What is wrong with his justification?

But statistics is a fairly exact science, and statisticians are usually very good about being explicit about their assumptions and reasoning. If you can't point to what is wrong except a dislike of Ersby's conclusion, that's not very credible. Especially since you've admitted upthread that your mathematical understanding is weak. Why should I trust your opinon when it conflicts with the experts'?

How does this address anything I said?? I stated that you can calculate the results this way if you like, but just don't whine when this post-hoc analysis revealed a baseline below 25%.

And you have still to justify how a 32% hit rate would be expected without any psi. Give me your arguments. Or if you can't then shut it. I grow weary of your idiocies.

 

[drkitten]

How does this address anything I said?? I stated that you can calculate the results this way if you like, but just don't whine when this post-hoc analysis revealed a baseline below 25%.

And you have still to justify how a 32% hit rate would be expected without any psi. Give me your arguments.

I don't have to justify that, as that's a claim I've never made. I like to look at the evidence before I make claims.

But if you want a possible way in which a 32% hit rate might not be significant when compared with a 25% baseline, issues of sample size will do nicely. Running thirty-six trials with a 25% baseline would give you an "expected" nine hits (25%), but you would need fourteen hits (39%) to achieve the standard alpha cutoff. Twelve hits (33%) wouldn't even qualify as a "trend" under the usual standards.

How many trials were run in the experiment under discussion?

 

[amherst]

I don't have to justify that, as that's a claim I've never made. I like to look at the evidence before I make claims.

But if you want a possible way in which a 32% hit rate might not be significant when compared with a 25% baseline, issues of sample size will do nicely. Running thirty-six trials with a 25% baseline would give you an "expected" nine hits (25%), but you would need fourteen hits (39%) to achieve the standard alpha cutoff. Twelve hits (33%) wouldn't even qualify as a "trend" under the usual standards.

How many trials were run in the experiment under discussion?

As of 1997 there had been 2,549 ganzfeld sessions reported. A meta-analysis revealed the average hit rate to be at 33.2%.

amherst

 

[drkitten]

As of 1997 there had been 2,549 ganzfeld sessions reported. A meta-analysis revealed the average hit rate to be at 33.2%.

And what did the meta-analysis reveal the standard deviation of the hit rate to be?

 

[AOK Tiger]

Ian,

I actually (sort of) agree with you about the expected 25 % average. (if the pictures where not open to conjecture)

BUT…..

YOU have to agree that 25 % can ONLY be expected with SIMPLE cards.

If you had 4 distinct patterns from a random deck and you got 32 % I would wholeheartedly agree that there was some weird effect that could mean some “psi” was at work !

The reason these test will ALWAYS be disputed by sceptics is they ARE open to conjecture.

Simple cards would not be !

Why oh why won’t you “psi” lovers address this point ?

 

[Paul C. Anagnostopoulos]

Ian said:
Why do we never hear Skeptics complain that the average hit rate expected by chance should be below 25%?? Well we know the reason for that; because they are utterly biased and irrational when it comes to the subject of the paranormal, that's why.

But we do complain about hit rates below chance, when parapsychologists start talking about negative psi.

~~Paul

 

[!Xx+-Rational-+xX!]

The only bias present in skeptics is that which correctly leads towards the truth of reality!

Rather than being suggestive of PSI these experiments are strongly suggestive of believer's own stupidity and gullibility!

Just hope that the general public doesn't hear much about this ESP experiment nonsense since they aren't qualified to think for themselves! Only skeptics can do that since we alone are critical and base everything on fact!

There is nothing to this! Science doesn't allow it!

 

[AOK Tiger]

XRationalX..

Are you still continuing with your ONE joke bandwagon…

FIND A NEW JOKE…

You have passed from inanity to lunacy.. I wonder if you even realise we laugh AT you not with you !

 

[Ersby]

Sorry, Ersby, it is you who is mistaken. It was updated.

I was referring to this:

When Julie Milton completed it, it was found to be stat. significant.

The addition to the m-a (which relied entirely on one experiment for its effect size!) was not done by Julie Milton.

 

[Ersby]

As of 1997 there had been 2,549 ganzfeld sessions reported. A meta-analysis revealed the average hit rate to be at 33.2%.

amherst

Which meta-analysis?

 

[Lucianarchy]

I was referring to this:

I was referring to this:

"Milton subsequently organized and initiated an Internet debate of the ganzfeld research, a debate that was edited for publication by Schmeidler and Edge (1999). In her own contribution to that debate, Milton (1999) noted that when replications published after the Milton/Wiseman cutoff date are added to the database, the accumulated studies do, in fact, achieve statistical significance. " - Journal of Parapsychology. 2001, Vol. 65, No. 3, 000-000

 

[Lucianarchy]

Why did you say this when it had nothing to do with Milton "completing" the analysis?


~~ Paul

OK, strictly speaking she, personally, didn't complete the study. But she agreed with the the findings of the completed study and was instrumental in putting the record straight. Unfortunately, a lot of the so-called 'skeptical' sites, publications etc,. do not keep their records up to date, and most of the stuff out there only covers the original, unciompleted, wiseman/milton study. Here it is though:

"Milton subsequently organized and initiated an Internet debate of the ganzfeld research, a debate that was edited for publication by Schmeidler and Edge (1999). In her own contribution to that debate, Milton (1999) noted that when replications published after the Milton/Wiseman cutoff date are added to the database, the accumulated studies do, in fact, achieve statistical significance." Journal of Parapsychology 2001, Vol. 65, No. 3, 000-000

 

[Lucianarchy]

For JMA:

Hope you found the up to date information regardingHyman/Bem & Milton/Ganzfeld useful?

 

[JMA]

Hope you found the up to date information regardingHyman/Bem & Milton/Ganzfeld useful?

Yes, yes, thanks a lot! Fascinating (I'm a trekkies, so...).

I would like to ask: why do they use this kind of target in the Ganzfeld studies. I don't understand why they don't use the traditionnal Zenner Cards... With the Zenner Cards, it would be easier to be sure that "a hit is a hit", isn't-it?

See you,

 

[Ed]

Yes, yes, thanks a lot! Fascinating (I'm a trekkies, so...).

I would like to ask: why do they use this kind of target in the Ganzfeld studies. I don't understand why they don't use the traditionnal Zenner Cards... With the Zenner Cards, it would be easier to be sure that "a hit is a hit", isn't-it?

See you,

Does that tell you something?

 

[JMA]

Hi,

(sorry for my english)

Does that tell you something?

Bem & Honorton wrote this in this publication :

The sender is sequestered in a separate acoustically isolated room, and a visual stimulus (art print, photograph, or brief videotaped sequence) is randomly selected from a large pool of such stimuli to serve as the target for the session.

And I simply (it's a very "naive" question) wonder why an "art print, a photograph or a brief videotaped sequence" and why not the classical Zenner Cards...

I have seen a demonstration of the Ganzfeld procedure and it was a brief videotaped sequence, a short clip from "Star Wars: The return of the Jedi". Luke Skywalker is on a landspeeder in the woods.

So, the "psychic" says during the demostration: I'm seeing trees...

Is it a hit for you, or not?

Because, yes, you have trees in the brief videotaped sequence, but it would have been a far better "hit" if the psychic have said "I'm seeing a Star Wars movies", or even better, "I'm seeing a clip from Star Wars: The return of the Jedi", and even again better if the psychic have said "I'm seeing a clip from Star Wars: The return of the Jedi, and it is when Luke Skywalker is on a landspeeder in the woods".

So, that's the point who is puzzling me for the moment.

See you,

 

[Lucianarchy]

Hi,

(sorry for my english)



Bem & Honorton wrote this in this publication :



And I simply (it's a very "naive" question) wonder why an "art print, a photograph or a brief videotaped sequence" and why not the classical Zenner Cards...

I have seen a demonstration of the Ganzfeld procedure and it was a brief videotaped sequence, a short clip from "Star Wars: The return of the Jedi". Luke Skywalker is on a landspeeder in the woods.

So, the "psychic" says during the demostration: I'm seeing trees...

Is it a hit for you, or not?

Yes, it's a hit, as long as 'trees' are a significant aspect of the image. In respect of your zenner cards question, full 'in your face' images are much better, mainly because people who RV/ESP/whatever, tend to report that they can pick up 'perceptions' of images, rather than a 'Xerox'. The shapes are all b/w geometric shapes, no one claims to be able to reliably pick out one from eight or so similar shapes. IMO, the images in the target should be completely different. It is a common fallacy of pseudo-skeptics to assume that RVers can read the front page of The Times at a distance! No one ever claimed to do that. The effect is subtle, measurable but replicable.

 

[drkitten]

Yes, it's a hit, as long as 'trees' are a significant aspect of the image. In respect of your zenner cards question, full 'in your face' images are much better, mainly because people who RV/ESP/whatever, tend to report that they can pick up 'perceptions' of images, rather than a 'Xerox'. The shapes are all b/w geometric shapes, no one claims to be able to reliably pick out one from eight or so similar shapes.

This finding unfortunately raises the immediate issue of hunting bias, the tendency of people to find what they are looking for. A sufficiently creative individual can probably find a connection between any image and any statement. Furthermore, some images are more succeptible to hunting bias than others (an empty desert landscape --- think Tatooine --- will have fewer significant features than a photograph of a city street). This effect is extremely difficult to control for.

 

[Lucianarchy]

This finding unfortunately raises the immediate issue of hunting bias, the tendency of people to find what they are looking for. A sufficiently creative individual can probably find a connection between any image and any statement. Furthermore, some images are more succeptible to hunting bias than others (an empty desert landscape --- think Tatooine --- will have fewer significant features than a photograph of a city street). This effect is extremely difficult to control for.

I don't think anyone said it was easy!

But the same issue applies to the arguments which are sceptical of the results. The over all body of evidence suggests that it is highly unlikely that each and every one of the scientific experiments is due to an imagined candidate. We need to move on from suspicions and use scepticism to provide positive suggestions for controls.