Tuesday, June 12, 2007

Presentiment in the brain

This paper has been accepted in the Journal of Alternative and Complementary Medicine and will be published later in the year:

Models of the placebo effect: Investigating a possible retrocausal factor

Dean Radin, PhD & Eva Lobach, MS

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 one 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. EEG data were analyzed separately by gender.

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

Conclusions: This experiment, in light of 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 serious consideration of transtemporal or retrocausal factors.


Tor said...


It seems to me that the presentiment effect is the most easiest repeatable and robust psi effect to date. Am I correct?

It is strange that the effect seem to depend on sex though.

Dean Radin said...

I'm not sure I'd say that any psi effect was easy to repeat, but yes overall these effects do appear to be surprisingly robust.

We split the data by gender in this presentiment study because of previous (conventional) experiments suggesting gender differences in how visual information is processed by the brain. But whether gender is a meaningful component here is not clear to me. It might just be a fluke.

I'm just now finishing up phase I of a new experiment examining presentiment in pupil dilation, blinking and eye movement.

Tor said...

Yes, I agree that the gender differences might just be a fluke. The only one I know of that has found a significant gender difference is Dick Bierman. But I don't know if anyone else have been looking though.

M.C. said...

pupil dilation, blinking and eye movement.

I strongly suspect that my daughter has some kind of presentiment-like effect with blinking and having her picture taken.

The number of photographs of her with her eyes closed seems much higher than an estimate of how often she blinks.

This is for photographs taken with a digicam with a silent shutter and no flash. It will be interesting to read about your blinking study.

Dean Radin said...

This experiment is showing significantly more blinking (on average across many subjects) just before seeing emotional vs. calm pictures.

Perhaps if your daughter is shy of having her picture taken, she is sensing exactly the right time to blink to ruin the shot. It would be interesting to select people with that "skill" and see how they behave on a presentiment test.

Dave Smith said...


Could I ask whether you used a trial design similar to your previous presentiment experiments, or whether you used a "continous trial" design similar to the auditory presentiment experiments carried out by May and Spottiswoode?


Tor said...

Dean said:

This experiment is showing significantly more blinking (on average across many subjects) just before seeing emotional vs. calm pictures.

I would have guessed that pupil dilation would show evidence for presentiment(because of the fight-flight response), but not that blinking would give such an effect.

Have you seen any response in the pupil dilation?

David Bailey said...


Like Tor, the presentiment experiment has always intrigued me because it is simple, automatic, and presumably less likely to fatigue the participants.

Have you explored the idea of using pattern recognition software to get the computer to recognise the build-up to a flash/emotional image vs the build-up to a non-event.

This signal could be used in many ways. For example, it could be used to feedback to the subject his ability to anticipate the events (I assume they all know the purpose of the experiment).

Have you discovered any star anticipaters?

Dean Radin said...

This experiment uses subject-initiated trials, not a "free-running" design as used by May and Spottiswoode.

It shows significantly greater pupil dilation and blinking before emotional pictures as compared to calm pictures.

There's also evidence that pre-stimulus eye movement (where the eye is looking over time) differs depending on the emotionality and valence of the future image. I'm still working on this analysis, so I don't have high confidence in this result yet. But so far it appears that if the future image is high arousal/high valence then there is a positive correlation in eye movements before vs. while seeing the image. I.e., for arousing positive images (mostly erotic or extreme sport images) the eyes trace the same pattern before the image appears as when they are looking at the actual image.

And if the future image is going to high arousal/low valence then there is a negative correlation. I.e., before the image appears the eyes trace a mirror image of arousing negative images (mostly violent or gory images).

Dean Radin said...

David asked "Have you explored the idea of using pattern recognition software to get the computer to recognise the build-up to a flash/emotional image vs. the build-up to a non-event."

I've examined how reliable individual trials are in detecting the likely future. They appear to be weak predictors at best, and moreover the effects we see may be inherently statistical for logical reasons. I.e., if it is possible to know the future with certainty, then we can bilk the future, i.e. detect the future and then change it. That would cause a causal paradox, which I suspect Nature does not allow.

However, one can avoid the logical problems associated with causal paradoxes if a future event depends on present knowledge in some way. In this way detection of a future event with high certainty, with intent to change that future based on the knowledge, must occur, because otherwise the knowledge wouldn't have been available in the first place. Thinking about loops in time makes my head hurt.

Tor said...

Dean Radin said:
Thinking about loops in time makes my head hurt.

It's funny how hard it is for us here in the west (especially those of us with a scientific training) to wrap our minds around such strange time effects. I guess it doesn't help that since childhood we have been shown and told that time is linear.

Other cultures (some of them) have a totally different view of time, and don't feel this pain at all.

As I reflect back on my early youth I can remember a time when I hadn't put everything in categories (or at least they weren't so firm). Every new phenomena was experienced in the now. To make the mind shut up and stop analyzing is not as easy today.

David Bailey said...

Has anyone theorized about the relationship between presentiment and Benjamin Libet's neural timing experiments which seem to be accepted - even though they themselves are pretty strange. Both experiments seem to suggest that consciousness is spread out over a small time interval centered on the present.

Do subjects vary a lot in the extent that they show this effect?

Dean Radin said...

I've written about the relationship between the Libet results (and a few other effects like the flash-lag effect) and presentiment. The conventional idea is that the brain back-references some events, which creates a retrocausal illusion. The presentiment experiments put an entirely different spin on that interpretation.

The test-retest reliability in this experiment is not very good. I've run a few people repeatedly who have shown good reliability, but they are rare. Then again, high reliability even in conventionally robust tests, like Stroop, isn't as high as we might like.

David Bailey said...

I guess I feel that because presentiment seems tied up with Libet's observations, it is really part of ordinary consciousness - not an extra ability that most people don't possess. Maybe certain kinds of activity would sharpen up that ability - for example marshal arts or other kinds of high speed sports, such as football goal keepers.

Indeed, anyone who practices skills that involve split-second reactions might reasonably be expected to show enhanced presentiment.

J said...

Hi Dean,

J here. I am wondering, regarding presentiment, if your findings of discovering that the terrorist planes on 9/11 were not nearly as full as on any other 'regular' day, if those findings could be made part of the security procedures that airports could use as a way to examine the probability of a would-be terrorist spoiled flight. I understand security levels at USA airports are on a high at the moment and perhaps looking at seat capacity of the day versus usual seat capacity of the day could help to search out would-be terrorist plots in the making.

Is there already a tool in place to make use of large scaled psychic phenomena?



David Bailey said...

J's suggestion, while very interesting, would raise the thorny question as to whether people would feel a presentiment for an event that would not happen because the presentiment was acted on!

It is analogous to the idea of getting the standard presentiment experiment to analyse the subject's response and change the image accordingly. If you remember, Dean said that the statistics for one presentation would be too weak.

However, suppose he had a whole bank of subjects observing the same sequence.....


h13000 said...

All these precognition tests show are that our consciousness has a time lag in registering physical reality. Although it appears that the computer program is going to show a picture in t seconds, in physical reality the program has been designed to show the image in t minus the consciousness time lag. What these experiments show are that our nervous system registers the stimuli before our consciousness does – that is all. (please see Kornhuber's experiment)

Dean Radin said...

Yes, but not a delay of 3 to 5 seconds. If those delays were happening then none of us would be here, having all been eaten by tigers by now.

h13000 said...

Dr. Radin,

Your theory revolves around the assumption that our consciousness is in control and not simply an observer (Although this may be true on occasion, it is not a fair assumption to make when it comes to tasks that are related to survival). If one imagines the conscious mind as merely an observer, it becomes clear that reality can be construed in retrospect.

Also, tigers would presumably have their own awareness time lag.