“Dowsing” Bomb Detectors Worthless in Double-Blind Tests (Weird science edition: pole reversals too)

In a double-blind test, physicists have quite thoroughly debunked the GT200 “dowsing bomb detector” sold for absurd amounts of money. It’s just a metal rod on a bearing mounted in a pistol grip. The idea is that a very slight hand movement causes the rod to swivel left or right.

No surprise, then, that when asked to (blindly) find the box of 1600 amphetamine pills from among eight identical ones in a large room, a trained GT200 operator did no better than chance. (3/20 hits vs a stastically predicted 2.5/20)

However, dowsing has been around for more than 8000 years. (http://dowsing.barbfeick.com/history.htm ) Some people who use GT200 “bomb detectors” swear by them, and the dowsing field has many more legions of equally enthusiastic adherents ( http://www.westword.com/2002-05-30/news/divining-intervention/full/ ).

So what gives?

Here’s my theory. In the course of talking about body-language-reading and related fields, I’ve pointed out a few times that we’re surprisingly good at intuition… noticing little details and deriving conclusions that, while accurate, don’t appear to be fully supported by the clearly visible facts.

It’s my suspicion that the people who are successfully finding bombs and criminals with GT200 dowsing rods are using these devices to tap into their subconscious minds… maybe picking up microexpressions from the smugglers, maybe even factors we haven’t identified yet.

The “dowsing rod” is just a tool that shows micro motor movements, which the subconscious mind can control much more easily than the conscious one. Rather than requiring people to spend lots of time meditating or doing whatever other excercises traditionally get people in touch with the subconscious, the dowsing rod gives that part of the mind an easy way to say “Yo! Look over there!”

This theory is consistent with a skeptical review of the available literature (http://skepdic.com/dowsing.html) which found that dowsers weren’t bad at finding water “in the field” where not-yet-understood clues might exist, but weren’t very good at finding water in controlled settings.

For one thing, it turns out there’s at least some scientific evidence that the human body is EXTREMELY sensitive to very low-level magnetic fields. I’ve found as much with the micropower TMS. But another such field is the earth’s geomagnetic one… which is strongly affected by local soil composition and local artefacts (https://en.wikipedia.org/wiki/Magnetic_survey_%28archaeology%29).

[Note this theory doesn’t explain “map dowsing,” where people claim to find things just by “dowsing” a map of anywhere in the world… including oil, on behalf of various large oil companies. But I’m going to file that under “not enough research I can find on the subject.”]

Weird science:

I did find one very odd reference in the course of looking to magnetic fields. Given all the hue and cry about a magnetic pole reversal within the next few thousand years, it’s a bit disturbing. I haven’t been able to find an English reference, so here’s a translation from the German:
“Everyone knows we couldn’t live without the sun. But that we’d all die in three months without the Earth’s magnetic field is known by few outside the field of space-travel medicine.”*

After all, a pole reversal would result in a near-disappearance of the Earth’s field for a few hundred years at least.

* (http://www.ems-institut.de/content/view/71/67/ “dass wir ohne das MF nach 3 Monaten sterben würden, wissen außer die Raumfahrtmediziner die wenigsten”)


“The detection and identification of drugs and explosives is an important goal in the fight against crime. Indeed there are numerous promising methods for spotting this stuff that depend on technologies such as artificial noses, x-ray imaging, terahertz scanners and so on.

But there are also devices based on the controversial process of “dowsing” that claim to do a similar job. These devices consist of a pair of swivelling rods, are “powered” by the user’s electrostatic electricity and are supposedly capable of tracking illegal substances in tiny quantities over vast distances.[…]

The test is simple. They placed a quantity of amphetamines–over 1600 pills-or some bullets, in one of eight boxes chosen at random in a large room. A GT200 operator, in this case a soldier, then entered the room and used the device to locate the stash.

They repeated this four times, each time allowing the solider to see where the contraband was place and then a further twenty times without the soldier being aware of the box in which it was placed.

The results are unsurprising. When the solider was aware of the location, the GT200 worked perfectly, identifying the correct box on all four occasions.

But when the soldier was unaware of the location, the GT200 located the contraband on only three occasions out of 20, a result that is entirely compatible with chance. “

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