Friday, October 12, 2007

Presentiment in the brain

Just published:

Toward Understanding the Placebo Effect: Investigating a Possible Retrocausal Factor, Dean Radin and Eva Lobach, Journal of Alternative and Complementary Medicine, Volume 13, Number 7, 2007, pp. 733–739

Objective: Conventional models of placebo effects assume that all mind–body responses associated with expectation can be explained by ordinary causal processes. This experiment tested whether some placebo effects may also involve retrocausal, or time-reversed, influences.

Design: Slow cortical potentials in the brain were monitored while adult volunteers anticipated either a flash of light or no flash, selected with equal probability by a noise-based random number generator. Data were collected in individual sessions of 100 trials, contributed by 13 female and 7 male adult participants.

Outcome measures: Ensemble median slow cortical potentials 1 second prior to a light flash were compared with the same measures prior to no flash. A nonparametric randomized permutation technique was used to statistically assess the observed difference. Electroencephalographic data were analyzed separately by gender.

Results: Females’ slow cortical potentials significantly differentiated before stimulus onset (z = 2.72, p = 0.007, two-tailed); males showed a suggestive effect in the opposite direction (z = 1.64, p = 0.10, two-tailed). Examination of alternative explanations indicated that the significant effect in females was not caused by anticipatory strategies, equipment or environmental artifacts, or violation of statistical assumptions.

Conclusions: This experiment, in accordance with previous studies showing similar, unconscious “presentiment” effects in humans, suggests that comprehensive models seeking to explain placebo effects, and in general how expectation affects the mind and body, may require consideration of retrocausal influences.

To download this article for free, go here.

26 comments:

bqeu said...

I'm not up on the latest theories of PK and retrocausation, but I was trying to understand why you prefer retrocausation as an explanation of your results instead of an unconscious PK effect.

Based on your empirical results or from semantics I don't see a preferece for either term except, with the PK explanation, cause comes before effect which is usually how people view the world.

Is it because the model for how PK works is also by choosing a possible future so that PK is the same thing as retrocausation? In which case retrocausation is semantically preferable?

Unless that is proven to be the underlying mechanims of both phenomena isn't PK an equally likely explanation?

Dean Radin said...

The reason these results look more like retrocausation than PK is because the number and sequences of flash/no-flash targets were in alignment with chance expectation. If the results were due to PK we might expect non-random distributions or non-random autocorrelations in the target sequences. The same argument holds for other presentiment experiments, where there is no clear evidence that the targets were selected nonrandomly. And thus a passive perceptual explanation seems more plausible than an active influence explanation.

bqeu said...

Have there been any experiments of this type that examine whether the amount of time elapsing between the effect and cause has any effect on strength of the presentiment effect?

Dean Radin said...

Within this design, no. But in earlier precognition experiments a meta-analysis suggests an inverse relationship between the strength of the effect and the latency between cause/effect (or vice versa given that we're dealing with apparent retrocausal effects). I.e., strength goes up for shorter latencies.

Dave Smith said...

Hi Dean,

I'm interested to know if you submit these kinds of studies to 'mainstream' journals for publication?

Thanks
Dave

Dean Radin said...

Mainstream is disciplinary-specific. Within the already large and growing discipline of CAM research, the JACM and Explore are mainstream.

Both are published by mainstream academic presses, the former by Mary Ann Liebert, Inc. and the latter by Elsevier. And both journals are indexed in all the usual online bibliographic indices.

Because mainstream is a social construction, one way to assess the "mainstreamedness" of CAM research is by what the science media pays attention to. Apropos, on Friday I was interviewed about the intentional chocolate experiment (mentioned in another post) by a reporter for Earth & Sky, a science program on National Public Radio (www.earthsky.org).

Dave Smith said...

I guess I've never looked at it like that before. When I sit down and read this kind of presentiment study, I tend to look at it primarily as a neurophysiological or neuropsychological phenomena. I know that it doesn't matter where such a study is published in terms of content. Anyone can get just as much out of it if it were published in JACM or the Journal of Neurophysiology. But in terms of stirring up interest in the field, do you think its usefull to look at traditional journal 'impact' factors? I don't know how JACM fairs and I don't want to sound like I'm making any credibility judgements there. We all know that Nature has the largest 'impact' factor for a variety of reasons. But that doesn't mean a study published in a lower 'impact' journal is any less valuable than if it were published in Nature. I guess what I'm trying to say is that I would like to as many neurophysiologists exposed to such a study as possible! If only to spark some replications from scientists who do not usually do such experiments. I suppose I get a little frustrated with the lack of academic action in response to such phenomena.

Swan said...

You would probably like the movie Signs. I personally don't believe in psi at all, but the movie is really about that and it's like a little fable about people who don't believe versus people who do. It's easy to see it represents your views perfectly.

Dean Radin said...

I did like the movie Signs. One person's meaningless coincidence can be perceived by another person as a meaningful synchronicity.

Of course, the difference between surprising events in daily life vs. controlled lab experiments is that for the former we can't be sure if something is chance or not, but for the latter we can precisely calculate the difference between chance and non-chance.

Swan said...

Dr. Radin wrote:

I did like the movie Signs. One person's meaningless coincidence can be perceived by another person as a meaningful synchronicity.

I thought that was kind of more how they were putting it towards the end of the film, but I think by the time the film is over it's pretty clear that psi stuff is supposed to be going on. The wife has some kind of flash before she dies, and gives Mel Gibson just the right mental phrase he needs to know just the right thing to do when he thinks of his wife's death when he's confronted by the alien. Maybe M. Night didn't set out to offer an opinion about psi when he made this movie, but I don't think he was trying to be a relativist or something. I think he was trying to say that stuff in the universe that can maybe take care of us is true, and you should at least be open to that (whether it's the "universe" manifested in psi, or "God," or whatever you want to call it).

Sorry for the off-topic comment, but you don't have an e-mail on the site.

Dean Radin said...

My email is listed on the bio page at www.deanradin.com. To repeat, it's dean at noetic dot com.

Peter Venkman said...
This comment has been removed by a blog administrator.
Atheistic Mystic said...

Dean,

How carefully is latency taken into account in presentiment experiments, generally speaking?

A friend of mine said that even a slightly longer cable from the tone generator to the recorder than the one from the heart rate monitor to the recorder can make it appear as if there is precognition.

He said if a tone is generated (Time A), and the subjects' heart rate is monitored (Time B), they must take into account the time it takes for the source pulse to travel to the recording device. This is an issue in the recording industry and processing times have to be taken into account to ensure proper tracking.

Dean Radin said...

If presentiment effects were on the order of milliseconds or less in advance of the stimulus, then potential signal latencies would have to be taken into account. But for the slow-moving autonomic measures we've been measuring, it is not an issue. The effects we see are 3 to 5 seconds in advance of the stimulus.

In any case, the physiological signals we record are marked (in time-synched channels) within a millisecond of the stimulus onset, so even when using faster-moving EEG signals potential time lags aren't an issue.

Atheistic Mystic said...

Dean,

Regarding this paper:

http://www.scientificexploration.org/jse/articles/pdf/18.2_radin.pdf

A friend of mine said:

"there are no presentations of confidence intervals or error bars. Standard physiology practice would be to divide the data into two independent sets and display them superimposed to demonstrate repeatability. The statistical method described is far more complex than the nature of the data calls for (a simple t-test comparing the AUC from 0-3 seconds between the two groups would have sufficed). Taken together, these are all suspicious. Add to this that the data is far cleaner than other published data from dermal galvanic response studies run in reputable labs.

taken together, these points suggest what I will charitably call a lack of credibility. The experiment is simple enough. I would like to see it run under an independent site audit."

How do you respond?

Dean Radin said...

> The statistical method described is far more complex than the nature of the data calls for (a simple t-test ...

The computational statistic used is actually very simple, but more importantly it avoids parametric assumptions and takes into account autocorrelations inherent in the data. A simple t-test would not be appropriate. In any case, the analytical procedure used comes directly from the psychophysiological literature. I agree that it can be useful to plot error bars (especially for those who only look at the figures).

> the data is far cleaner than other published data from dermal galvanic response studies run in reputable labs.

The curves are ensemble averages over many repeated trials. Given the low-noise nature of the data, the ensemble mean should be very smooth. Indeed, similar curves involving skin conductance level (not "dermal galvanic response") data are commonly observed in the psychophysiological literature.

> The experiment is simple enough. I would like to see it run under an independent site audit.

I don't know what an "independent site audit" is supposed to mean, but the experiment has been independently and successfully replicated in skin conductance, heart rate, EEG, and in my last (not yet published) study, pupil dilation.

Atheistic Mystic said...

Thank you, Dean!

I was wondering if you would take a gander at this:

http://forums.randi.org/showthread.php?t=123007

A thread titled: Simulating "Presentiment" Experiments

---------------------------------
"A series of experiments by Dean Radin and others purport to show that the human mind reacted precognitively to stimuli.

The basic design of these experiments is that people are shown, in a random order, a series of photographs - some provoking a strong emotional reaction, some not. Skin conductance is measured both before and after and the results seem to show that dermal activity is higher when the emotional provoking is shown, both before and after the photograph is actually displayed. See Electrodermal Presentiments of Future Emotions for example. In some experiments MRI is used.

I decided to see if these results could be explained by an anticipation effect based on the photographs previously seen. It turns out they can.

The simulation produces 10 seconds worth of data and randomly chooses a state 1 or 0 after the first 5 seconds - representing "emotional" and "calm". The data in the first half of the run is influenced by variables based on past states, the second half is influenced by a function simulating an emotional reaction. A purely random number is also generated to simulate noise.

And yet when data from a series of tests is aggregated, it appears that there is a difference both before and after the random number is actually generated."

[...]

http://picasaweb.google.com.au/robin1658/Presentiments#
----------------------------------

Do you know of a link to a study that shows that an anticipation effect is inapplicable?

Thanks!

Dean Radin said...

I discussed this fellow's proposed anticipatory strategy in the very same published paper that he cites. I suppose I have to assume that he didn't actually read the paper.

The idea is well understood and has been studied in detail.

The bottom line is that analysis of the actual physiological data recorded in these studies does not support the idea that the results can be explained by anticipatory strategies. This is true not only for the data in my studies, but also for the successful replications reported by others.

Dean Radin said...

Roger K commented on this too, writing among other things:

"I wonder how thoroughly "Robin" read p. 269-271 in your 2004 study before he created this simulation?"

Robin said...

"I discussed this fellow's proposed anticipatory strategy in the very same published paper that he cites. I suppose I have to assume that he didn't actually read the paper."
I did, but it was not clear from the bizarre procedure you were following that you were talking about the same thing.

Instead of simply analysing the data in the experiment you perform a new experiment, using a smaller sample and a different protocol.

You say the effect is well understood but you completely leave out any analysis of runs "emotional" trails.

And as I point out, the strategy you use to rule out anticipation effect in your experiment also rules out the anticipation effect in my simulation.

Even though we know it is there.

Robin said...

"Roger K commented on this too, writing among other things:

"I wonder how thoroughly "Robin" read p. 269-271 in your 2004 study before he created this simulation?""
Well enough to demonstrate (in post #23) that the proposed strategy to test for the anticipation effect would be ineffective.

Dean Radin said...

I'm afraid I don't understand your comments. E.g., you completely leave out any analysis of runs "emotional" trails. What does this mean?

Robin said...

You are assuming that the results could only be an artifact of successive runs of "calm" trials before an "emotional" trial and do not take into account that it could also be an artifact of changes in successive runs of "emotional" trials before a "calm" trial.

Dean Radin said...

In the description of your simulation you write: "I am increasing the anticipation factor if the previous state is 'calm' and decreasing it when the previous state is 'emotional.' This means that whenever there is a run of 'calm' the first 'emotional' is guaranteed to be a local maximum, similarly the first 'calm' after a run of 'emotional' data will be a local minimum."

What we tested on actual data recorded in these experiments is whether this plausible-sounding strategy was actually followed. The answer is no, so the presentiment effect is not adequately explained by this strategy.

Sherri said...

Dr. Radin, would you be so kind as to give me a simplified explanation of your randomized permutation analysis method, such as the one used in the dog telepathy experiment with Shelldrake? I am a beginning statistics student trying to understand this method, so basic would be great . . . thanks so much!

Dean Radin said...

Sherri, if you're referring to the paper "A Dog That Seems to Know When His Owner Is Coming Home: Effect of Environmental Variables," the permutation method I used is described in that paper.

A randomized permutation technique is a type of computational statistic. Monte Carlo and bootstrap methods are other commonly used methods.

Permutation methods compare an observed measurement to a distribution of similar measurements constructed by randomly permuting one or more key variables associated with the original measurement. It allows you to ask whether the original measurement was really unique, or whether it tends to show up by chance (just like many other statistical tests). It is useful when the actual measurement distribution is unknown, or known but skewed, or otherwise unsuitable for the usual array of parametric statistics.