• Quick note - the problem with Youtube videos not embedding on the forum appears to have been fixed, thanks to ZiprHead. If you do still see problems let me know.

Persinger's Magnetic field hypothesis

Dr B

Muse
D
Joined
May 17, 2006
Messages
515
Micheal Persinger is well known for his theory suggesting that some apparitional experiences may be due to the brains of certain observers being exposed to complex low-frequency magnetic fields. Complexity more than field-strength seems crucial. He applies these fields to brains in his lab and there is some field-based evidence as well (magnetic hot-spots have been documented where observers of strange phenomena have been located).

So here - seeing a ghost could be little more than a magnetically induced hallucination. I think the idea has some merit - but there are problems.

There has been a failure to replicate (A Swedish group I believe) - however there do seem to be good reasons for that (not a within subjects design / short exposure times / did not follow the full and correct procedure, etc). Others have replicated it (Koren / Richards etc) - but they are closely connected to the lab. Others do get effects with complex fields but at slightly higher amplitudes (Bell / Cook etc).

Anyway, it seems the idea may have merit, in certain cases, but the effect is weak. I was wondering what opinions were amongst all you clever people on the idea that complex magnetic fields have the capacity to stimulate vulnerable brains in the natural setting. Do you think it is a viable skeptical theory? If so, how do you think it works at the neuronal level?
 
Last edited:
It works like a MR scan. (Powerful and complex magnetic field. No hallucinations.) Only not even that much.
 
I am not so sure that is true at all. MRI scans do not produce complex weak fields. They produce strong simple ones. The fields need to be conststantly erratic so a brain cannot habituate - that is the principle I think.
 
Dr B said:
I am not so sure that is true at all. MRI scans do not produce complex weak fields. They produce strong simple ones. The fields need to be conststantly erratic so a brain cannot habituate - that is the principle I think.
Click to expand...
If the field was not rapidly varied in complex ways, there would be no brain scan.
 
I think you misunderstand what I mean by complex. An MRI scan generally uses fields in the Tesla region - you would never encounter them in the normal environment. They are turned on and off rapidly - but to the same amplitude and usually with standard temporal intervals. On the whole they have good spatial homogeniety as well.

Weak complex fields are nothing like that. They vary along a number of dimensions and are applied to the brain in a spatially complex manner (so there is little or no spatial and temporal stable pattern). This is nothing like an MRI scan.

Actually when you use a TMS coil with similar amplitudes you can get very specific effects - but again the biophysics are very distinct and not the types of things Persinger is talking about at all. Here I am trying to concentrate on the role of weak complex fields and whether the suggestion has merit - not anything like the fields you talk about.
 
Last edited:
Persinger is definitely an interesting guy. He has (as you hinted) a wired helmet set-up that can supposedly induce the feeling of a “sensed presence” at minimum, and a full-blown religious experience at max.

Susan Blackmore had a look at him:

In a December 2004 issue of Nature, reporting on the Granqvist/Persinger controversy, Susan Blackmore, a former academic psychologist and parapsychology researcher, expressed her reluctance to give up on the theory just yet: "When I went to Persinger's lab and underwent his procedures I had the most extraordinary experiences I've ever had." "I'll be surprised if it turns out to be a placebo effect."
Click to expand...
This from a pretty good Wikipedia article.

He does walk a line which, unfortunately, some of his advocates decidedly cross, such as Todd Murphy; who’s nonetheless a great fun read, and one of the more compelling woos out there, IMHO.
 
The Granqvist study was a very poor attempt at replication. They made a number of errors - including fudging the distinction between replicating an experiment and replicating an effect. They did neither.

For example, they used a between-subjects experiment. When dealing with these types of weak(ish) effects it is always better to use people as their own controls (within-subjects). Also, the stimulation time was only 15mins. Persinger typically uses around 40mins. If the effect is real it does take time -this has always been explicitly mentioned in the procedures. There also appears to be problems for the fields generated.

What all this does mean of course is that, if weak complex fields can interact with certain brains, then the effect seems subtle and relatively constrained. However, this may also be due to other factors, such as context, arousal etc.

Other researchers have reported similar effects and both Blackmore and Dawkins reported effects (though Dawkins only got a major headache) - so it may not simply be a case of belief and magnetic fields.

I still think the definative study needs to be done by a lab independent of Persinger to understand more about the fields themselves and their neurologically active components. I have found some associations between striking reports of haunt-type experiences in the field and magnetic anomalies - so I do have some field-based evidence in support of it. :D
 
Another thing to keep in mind is that Persinger often gets lots of reports in the baseline control condition (around 20%) - where no magnetic fields are applied.

So sensory deprivation alone, even over a short period of time, may be sufficient in some cases to make certain observers mis-interpret internal sensations :cool:
 
Ririon - I do think it is interesting that people do not seem to be greatly affected by such high basic fields as in MRI- its just a different biophysical mechanism I feel to the weak complex ones.....

TMS uses high specific fields and gets direct effects - but again, thats via a different biophysical mechanism...I would certainly be interested in why you think simple high fields applied as diffuse fields (as in MRI) have no effects.....I have my own ideas, but I am hardly a physicist.

J
 
Last edited:
Dr B said:
Another thing to keep in mind is that Persinger often gets lots of reports in the baseline control condition (around 20%) - where no magnetic fields are applied.

So sensory deprivation alone, even over a short period of time, may be sufficient in some cases to make certain observers mis-interpret internal sensations :cool:
Click to expand...
You can add expectation: I doubt that 5-6 years after Persinger did effectively start his research program in the early 1990's much 'naive' volunteers remained in the department he heads, and even on the entire campus of the Laurentian University.

Moreover, the devices used (pictures) don't look very easy to forget in 40 mn and the person is simply sitting in an armchair. So I am unsure to what extent this setting is comparable to classical sensory deprivation ones (floatation tank, etc.)
 
Indeed. I think when expectation is present this is a big factor. Although he still gets significant effects on top of this it is important to note that sometimes expectation alone and reduced sensory input can be sufficient.

I think weak fields can and do interact with brain processes - and although the biophysics are not well know there are some candidate ideas out there worthy of investigation.

I guess i would just like to see more independent lab replication and a good deal more about the magnetic signatures and biophysics sorted out.

Despite apparently researching this area for 25 years - Persinger has little to say about it.

btw - the recent discovery of biogenic magnetite in deep brain structures which are also prone to seizure (i.e., hippocomapus etc) seems exciting in terms of a potential mechanism of interaction. :)
 
Apologies for reserecting this thread but i am interested in further comments here (and am currently ploughing through numerous papers on bio-effects of weak magnetism which are often questionable).

My skepticism of Persinger's work could be summarised as (i) very few independent replications of his effects (those i know of that are independent of him - are still in his lab), (ii) obscure biophysical mechanisms for how such weak fields interact with brain processes (see above discussions).

However, field and laboratory studies do show some support.

To those of a physics inclination, would you say fields (even complex though weak ones) in the nT and uT (nano-tesla and micro-tesla range) could interact with a brain? I know I have tried to discuss this elsehwere, but in the past it has been hijacked and the discussion has suffered. I am appealling here to those who have the capacity to contribute to the notion that it could or could not be plausible from the perspective of physics?
 
I have a friend who used to work for Persinger. I'll link the thread to him.
 
Dr B said:
To those of a physics inclination, would you say fields (even complex though weak ones) in the nT and uT (nano-tesla and micro-tesla range) could interact with a brain?
Click to expand...

I think you've hit the main problem. There is no mechanism by which the human brain can be affected by magnets of any strength lower than frog-levitating power.

But psychology is pretty clear that monotonous stimulation (or boredom) can cause feelings of unease, paranoia and halucinations surprisingly quickly.
 
Loss Leader said:
I think you've hit the main problem. There is no mechanism by which the human brain can be affected by magnets of any strength lower than frog-levitating power.

But psychology is pretty clear that monotonous stimulation (or boredom) can cause feelings of unease, paranoia and halucinations surprisingly quickly.
Click to expand...


I agree the lack of mechanism is a problem - but is not strong evidence against the idea on its own. There is evidence for high-end uT and mT fields having effects on power-spectra EEG - these are well under frog-levitating levels - but i take your point.

I am not saying that all the research on really weak fields is false - just that maybe it is interacting with other factors (i.e., is not sufficient on its own). Those other factors could be neuronal susceptibility, belief, expectation, contextual....etc.
 
You must log in or register to reply here.

Back
Top Bottom