Research about premonition

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Research about premonition

#1  Postby Microfarad » Nov 14, 2012 3:48 pm

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Re: Research about premonition

#2  Postby Microfarad » Nov 20, 2012 3:58 pm

Come on, isn't anyone able to debunk this?
According to Occam's razor, there is an error somewere.
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Re: Research about premonition

#3  Postby gib » Nov 20, 2012 4:00 pm

i knew this would happen
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Re: Research about premonition

#4  Postby Ihavenofingerprints » Nov 20, 2012 4:05 pm

Might be more convenient if the abstract is pasted here:

This meta-analysis of 26 reports published between 1978 and 2010 tests an unusual hypothesis: for stimuli of two or more types that are presented in an order designed to be unpredictable and that produce different post-stimulus physiological activity, the direction of pre-stimulus physiological activity reflects the direction of post-stimulus physiological activity, resulting in an unexplained anticipatory effect. The reports we examined used one of two paradigms: (1) randomly ordered presentations of arousing vs. neutral stimuli, or (2) guessing tasks with feedback (correct vs. incorrect). Dependent variables included: electrodermal activity, heart rate, blood volume, pupil dilation, electroencephalographic activity, and blood oxygenation level dependent (BOLD) activity. To avoid including data hand-picked from multiple different analyses, no post hoc experiments were considered. The results reveal a significant overall effect with a small effect size [fixed effect: overall ES = 0.21, 95% CI = 0.15–0.27, z = 6.9, p < 2.7 × 10−12; random effects: overall (weighted) ES = 0.21, 95% CI = 0.13–0.29, z = 5.3, p < 5.7 × 10−8]. Higher quality experiments produced a quantitatively larger effect size and a greater level of significance than lower quality studies. The number of contrary unpublished reports that would be necessary to reduce the level of significance to chance (p > 0.05) was conservatively calculated to be 87 reports. We explore alternative explanations and examine the potential linkage between this unexplained anticipatory activity and other results demonstrating meaningful pre-stimulus activity preceding behaviorally relevant events. We conclude that to further examine this currently unexplained anticipatory activity, multiple replications arising from different laboratories using the same methods are necessary. The cause of this anticipatory activity, which undoubtedly lies within the realm of natural physical processes (as opposed to supernatural or paranormal ones), remains to be determined.


I'm not familiar with a lot of the terminology here. What exactly is going on?
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Re: Research about premonition

#5  Postby Thommo » Nov 20, 2012 4:06 pm



I don't know I'd call it deceit, but publication bias, the file drawer effect and improper use of meta-analytic techniques are all strong possibilities.

I'm particularly sceptical of the claim:-
"The number of contrary unpublished reports that would be necessary to reduce the level of significance to chance (p > 0.05) was conservatively calculated to be 87 reports."

In light of the fact that this was a meta-analysis of just 26 studies meaning that 26 studies of equal and opposite finding would neutralise the results entirely.
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Re: Research about premonition

#6  Postby tolman » Nov 20, 2012 6:19 pm

I'm assuming the meta-analysis did check for each individual response being 'correct' with regard to an individual stimulus, rather than simply having a positive correlation between response pairs before/after any particular stimulus?

I'm sure that should be covered somewhere in the paper, but an answer didn't leap out at me on a quick read through (presumably my fault, due to my rusty statistics).

Clearly, simply finding positive correlation between before/after responses wouldn't necessarily demonstrate anything of value in terms of premonition.
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Re: Research about premonition

#7  Postby VK-machine » Nov 21, 2012 10:27 am

Microfarad wrote:Come on, isn't anyone able to debunk this?
According to Occam's razor, there is an error somewere.


The "expectation bias" mentioned in the paper probably goes a long way to explaining the seeming effect. I don't think there's anything to debunk there.
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Re: Research about premonition

#8  Postby Microfarad » Nov 21, 2012 4:23 pm

Right, only the "positive" experiments are published. Thank you. :thumbup:
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Re: Research about premonition

#9  Postby jerome » Nov 22, 2012 10:49 am

I actually have read the paper, and we I don't think we can invoke File Drawer effects to explain anything - that was clearly looked for: this is Jessica Utts after all. I'll see if I have time today to post some stuff on the FD measures employed. Don't forget File Drawer Effects were pretty much first noted in parapsychology; it took a long time for understanding of the issue to filter through to mainstream science. I suspect inclusion criteria might be more interesting as a factor: but this is just another in a long line of meta-analyses of various psi claims showing a small but consistent effect, like Andrew Endersby's recent study of the Ganzfeld database, or the many that fill Dean Radin's books. Jessica Utts is a first rate statistician, so I doubt I will find any flaws even if they exist -- I'm simply not good enough at stats.

I will have a good look, but I'm away this week and psi papers bore me to tears. Not really my thing!
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Re: Research about premonition

#10  Postby jerome » Nov 22, 2012 10:54 am

Microfarad wrote:Right, only the "positive" experiments are published. Thank you. :thumbup:


That is the one thing we can be sure is NOT happening here. Well fairly sure. In parapsychology there is the 1981 ( I think) Honorton-Hyman concordat, which was an agreement that the peer reviewed journals would publish failed replications irrespective of the papers merits, to help reduce file drawer effects. So even bad papers are published, but with critical commentary. I mentioned this last year when there was the problem with Ritchie, French and Wiseman having problems placing their failed replication of Bem's precognition paper - any peer reviewed parapsychology journal would have been required to publish it: it was simply the mainstream psych journal who published the original research who failed to publish it. (t was eventually as I recall published on PlosOne. Wiseman maintained the experimental registry where Bem replications were to be declared before being conducted, and then all results were to be analysed and published, again to prevent File Drawer Effects. He said last year they would be out soon, but I have not seen the results yet, unless they were presented at the SPR conference on a day I was not there?

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Re: Research about premonition

#11  Postby Thommo » Nov 22, 2012 11:16 am

jerome wrote:That is the one thing we can be sure is NOT happening here. Well fairly sure. In parapsychology there is the 1981 ( I think) Honorton-Hyman concordat, which was an agreement that the peer reviewed journals would publish failed replications irrespective of the papers merits, to help reduce file drawer effects.


As has been noted before on this topic, this is very far from sufficient. There are huge numbers of parapsychological papers that are not repetitions, but variations on a theme, by selection of the newer variations, there simply cannot be time for them all to have been replicated enough times to neutralise the statistical effect to the level that would be required to eliminate the file drawer effect.
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Re: Research about premonition

#12  Postby jerome » Nov 22, 2012 11:18 am

Yes. Variations on a theme, conceptual replications, are not included in the inclusion criteria. I wrote a long response to Wiseman on this two years back - i'll link it later.

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Re: Research about premonition

#13  Postby Thommo » Nov 22, 2012 11:20 am

jerome wrote:Yes. Variations on a theme, conceptual replications, are not included in the inclusion criteria. I wrote a long response to Wiseman on this two years back - i'll link it later.

j x


Quite, and what were the inclusion criteria for this meta-study?

A study was defined as a unique (not previously reported) examination of physiological responses to stimuli or events in one group of human participants; a report could include more than one study.


I.e. they only looked at the variations on a theme, not it would seem the replications, which would seem to directly counteract the attempt to neutralise the file drawer effect.
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Re: Research about premonition

#14  Postby VK-machine » Nov 23, 2012 5:02 pm

Microfarad wrote:Right, only the "positive" experiments are published. Thank you. :thumbup:

Not quite. This expectation bias thing is unique to these studies. Put simply, the statistical methods can make it look there is premonition going on when in actuality it is only normal human expectation.
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Re: Research about premonition

#15  Postby Microfarad » Nov 24, 2012 9:21 am

VK-machine wrote:Put simply, the statistical methods can make it look there is premonition going on when in actuality it is only normal human expectation.

How does it happen?
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Re: Research about premonition

#16  Postby VK-machine » Nov 24, 2012 11:34 am

Microfarad wrote:
VK-machine wrote:Put simply, the statistical methods can make it look there is premonition going on when in actuality it is only normal human expectation.

How does it happen?


There is some variation among those experiments. The typical experiment measures skin conductance, which is basically how sweaty you are. Because of that skin conductance can tell you how excited someone is.
When you are shown an exciting image, one that is violent or sexual, your skin conductance will jump up for a few moments.
In these experiments, subjects were shown exciting and boring images in random. When they saw the exciting images, their skin conductance jumped. That is absolutely normal.
Parapsychologists claim that, on average, skin conductance is slightly higher before exciting images.

The expectation bias works like this:
Every time a boring image is shown, you get a little bit more excited in anticipation of the coming violent or sexual image. But when you finally see the exciting image, you relax.
The result of getting more and more excited during a sequence of calm images is that you will be most excited right at the end of the sequence, before the exciting image.
This means that, on average, you will be more excited before exciting images.

One important disclaimer:
It has not been investigated if that can really explain the supposed effect. Based on what we know of human nature there should be some expectation bias but it is not known what influence exactly it would have in these experiments. It's unlikely that this will get much attention. Parapsychologists don't study things, or try to explain them. They just try to find reasons why something cannot be explained.
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Re: Research about premonition

#17  Postby Microfarad » Nov 25, 2012 10:57 am

VK-machine wrote:
Microfarad wrote:
VK-machine wrote:Put simply, the statistical methods can make it look there is premonition going on when in actuality it is only normal human expectation.

How does it happen?


There is some variation among those experiments. The typical experiment measures skin conductance, which is basically how sweaty you are. Because of that skin conductance can tell you how excited someone is.
When you are shown an exciting image, one that is violent or sexual, your skin conductance will jump up for a few moments.
In these experiments, subjects were shown exciting and boring images in random. When they saw the exciting images, their skin conductance jumped. That is absolutely normal.
Parapsychologists claim that, on average, skin conductance is slightly higher before exciting images.

The expectation bias works like this:
Every time a boring image is shown, you get a little bit more excited in anticipation of the coming violent or sexual image. But when you finally see the exciting image, you relax.
The result of getting more and more excited during a sequence of calm images is that you will be most excited right at the end of the sequence, before the exciting image.
This means that, on average, you will be more excited before exciting images.

One important disclaimer:
It has not been investigated if that can really explain the supposed effect. Based on what we know of human nature there should be some expectation bias but it is not known what influence exactly it would have in these experiments. It's unlikely that this will get much attention. Parapsychologists don't study things, or try to explain them. They just try to find reasons why something cannot be explained.

Understood. Thanks. :)
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Re: Research about premonition

#18  Postby Spearthrower » Jan 01, 2013 8:22 am

Microfarad wrote:Come on, isn't anyone able to debunk this?
According to Occam's razor, there is an error somewere.



As a random aside, I've done research on premonitions for an author writing a book on the topic. The number of cases that actually worked out is surprisingly few, but the selection bias is surprisingly high.
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Re: Research about premonition

#19  Postby quas » Jan 29, 2013 2:53 pm

Spearthrower wrote:As a random aside, I've done research on premonitions for an author writing a book on the topic. The number of cases that actually worked out is surprisingly few, but the selection bias is surprisingly high.

So despite the many many false positives encountered, you still acknowledge that a few of them could be are legit?
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