Magnetic Fields: Detection & Measurement

bakelite brain

Junior Acolyte
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#62
Did anything come of this research?

I am developing a 300Hz to 15 kHz VLF receiver to listen to whistlers, the dawn chorus, etc.


(That's not my recording by the way!)

But it's occurred to me that VLF baseline recordings made miles away from standing stones (and power cables!) and then around standing stones, both compared and displayed using software in the video may be revealing.

Did anyone contact the VLF yahoo group I suggested?
 
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#63
Humans able to detect magnetic fields? Farmers will want grants for those fields.

A study published today offers some of the best evidence yet that humans, like many other creatures, can sense Earth’s magnetic field.

But it doesn’t settle other questions that have swirled around this contentious idea for decades: If we do have a subconscious magnetic sense, does it affect our behavior? And does it arise from an iron mineral found in our brains, as the authors believe?

“I think this paper will make quite a splash,” says Peter Hore, a physical chemist at the University of Oxford in the United Kingdom. But, he adds, “Independent replication is crucial.”

A variety of species—bacteria, snails, frogs, lobsters—seem to detect Earth’s magnetic field, and some animals, such as migratory birds, rely on it for navigation. But testing for the sense in humans has been tricky. Experiments in the 1970s that asked blindfolded participants to point in a cardinal direction after being spun around or led far from home yielded inconsistent results.

https://www.sciencemag.org/news/201...ly_2019-03-18&et_rid=394299689&et_cid=2721870
 
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#64
Humans able to detect magnetic fields? Farmers will want grants for those fields.

A study published today offers some of the best evidence yet that humans, like many other creatures, can sense Earth’s magnetic field.

But it doesn’t settle other questions that have swirled around this contentious idea for decades: If we do have a subconscious magnetic sense, does it affect our behavior? And does it arise from an iron mineral found in our brains, as the authors believe?

“I think this paper will make quite a splash,” says Peter Hore, a physical chemist at the University of Oxford in the United Kingdom. But, he adds, “Independent replication is crucial.”

A variety of species—bacteria, snails, frogs, lobsters—seem to detect Earth’s magnetic field, and some animals, such as migratory birds, rely on it for navigation. But testing for the sense in humans has been tricky. Experiments in the 1970s that asked blindfolded participants to point in a cardinal direction after being spun around or led far from home yielded inconsistent results.

https://www.sciencemag.org/news/201...ly_2019-03-18&et_rid=394299689&et_cid=2721870
Interesting.
 
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#66
It's only 34 people. I'll withhold judgment.
Well, that and that they only detected a change in brain waves in the presence of magnetic fields of a type the earth naturally has (in about a third of the subjects). You'd hardly expect anything else, as the brain, the little we know about it, is quite electrical.

There's no suggestion the subjects could really tell that anything had happened. Plus what's the margin of error on the measurements...?

I don't see a control group...

I'd imagine his audience of sceptics scientists will pull the protocol to bits.
 
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#67
Well, that and that they only detected a change in brain waves in the presence of magnetic fields of a type the earth naturally has (in about a third of the subjects). You'd hardly expect anything else, as the brain, the little we know about it, is quite electrical.

There's no suggestion the subjects could really tell that anything had happened. Plus what's the margin of error on the measurements...?

I don't see a control group...

I'd imagine his audience of sceptics scientists will pull the protocol to bits.
I dashed that smart-arsed reply off, with a slice of toast in one hand and the laptop-bag in the other...

I decided to spend my lunchtime reading the paper - it's a topic that interests me as I’m something of ‘super navigator’ and can find my way about with seldom erring accuracy although my own observations are, that this is based on visual cues and to a limited extent, knowing which (compass) direction I’m going in.

Kudos to the authors for making the paper freely available and also the results/data. It very complete. You could recreate this experiment from the paper and the analysis from the data. That in itself is far less common that you might suppose.

I’ve not seen many so well constructed experiments of this type, that is physical phenomena interacting with people. They’ve really done a pretty good job and have bothered to understand the physics and the maths as well as the neuroscience. Coupla you guys can check the maths better than I, comparatively weak there myself ;)

The tone is little too sure of itself. For example, the significance statement; “Either we have lost a shared, ancestral magneto sensory system, or the system lacks a conscious component with detectable neural activity but no apparent perceptual awareness by us” doesn’t include a condition that the experiment itself may be a type one error and that a third option is that there is no such mechanism. I’m also worried when one of the experimenters in an evangelist for the cause – far too easy for bias to creep in then, even with the best of intentions. The conclusion is also ‘too sure’ and should perhaps use wording like "supports the hypothesis that...”.

'Because it's people’, a completely double blind methodology would have been appropriate. Participants were blind to Active vs. Sham mode, trial sequence and trial timing; this is good, I’d like all experimenters to have been in the same boat. This is not stated to be the case.

I note the participant briefing is not in the paper nor was there any suggestion of a debriefing. What were the participants told to avoid priming effects? All experiments with people as subjects generally have to mis-lead (although ethically) as to the true nature of the experiment to avoid priming effects skewing the results. In the interest of good ethics, one then de-briefs participants, telling the truth, at which point consent may be withdrawn and the data destroyed. This concerns me, it’s a big omission.

I’d prefer the study to have been between groups, that is a dummy/control group that were sat in the same room and subjected to the same protocol, but a static field consistent with the earth’s local magnetic field, turned on an off between runs. I’d prefer if the switch positions were automated (from ‘real’ to ‘sham’) and the experimenters never knew which was which until the results are collated. We also don’t want EEG ‘adjustment’ going on while the field is changing or not, notwithstanding those changes required to even out response between participants, hence ‘double blind’.

Overall, I’d say they may well be onto something, fascinating and IMO this result supports the hypothesis that changes in the magnetic field can affect aspects of the brains electrical behaviour. I’d draw the line at saying the experimental results ‘strongly supports’, until the experiment is repeated with:
  • Totally double blind protocols AND a control group.
  • A larger sample size for completed runs, 50 is a good number as dissertation studies (for example) are considered in a far more positive light once N >50 for good reason.
  • A briefing statement that negates priming effects and an appropriate de-briefing.
  • I’d consider hearing tests for the participants, especially is the age range is large, this would be to rule out the effects of auditory cues verses age.
  • A couple of the P values are in the range ‘so good they’re suspect’. I don’t suggest this is something one might use to invalidate the study, rather that the study must be repeated double blind and with no priming to ensure that the result is repeatable and real.

Coupla other things:

Sensible dummy objects used as controls for the EEG.

Samples size small, but typical for this type of paper.

Downward field sensitivity has a precedent in robins - they've been show to navigate using the angle on the magnetic field to the ground.

Some participants didn’t have SHAM data and were excluded. So even smaller sample's data was actually analysed.

Fascinating possibility that clockwise and counter-clockwise give different results in declination. I’d hypothesise that the east to west movement of the sun or the earth’s rotation might be a factors - assuming the effect is really there.
 
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#69
Kirschvink has published on dogs' magnetic sensitivity and also the idea of earthquake precursors.
Yeah, that's why I noted he was a zealot for the idea.
The tone is little too sure of itself. For example, the significance statement; “Either we have lost a shared, ancestral magneto sensory system, or the system lacks a conscious component with detectable neural activity but no apparent perceptual awareness by us” doesn’t include a condition that the experiment itself may be a type one error and that a third option is that there is no such mechanism. I’m also worried when one of the experimenters in an evangelist for the cause – far too easy for bias to creep in then, even with the best of intentions. The conclusion is also ‘too sure’ and should perhaps use wording like "supports the hypothesis that...”.
Always iffy and especially if double blind protocols are not observed. But I've seen a lot worse.
 
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Jim

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#70
Did anything come of this research?

I am developing a 300Hz to 15 kHz VLF receiver to listen to whistlers, the dawn chorus, etc.


(That's not my recording by the way!)

But it's occurred to me that VLF baseline recordings made miles away from standing stones (and power cables!) and then around standing stones, both compared and displayed using software in the video may be revealing.

Did anyone contact the VLF yahoo group I suggested?
Just a passing note, for what ever's it's worth. These low audio range frequencies can be very hard to detect using remote or wireless methods due to their long wavelengths, i.e.: The length for a 300 Hz wavelength is ~ 1000 Km's so unless your right on top of it you really can't practically receive the signal?
 
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