Dowsing has traditionally been a method of using a rod or stick to try and locate underground substances, usually water. It is based on no known science or law of nature.

Practitioners most commonly operate in an open field with a wishbone-shaped stick. At some point, the object will begin to shiver and point downward. There can be rare instances where this is caused by an electromagnetic force, but is almost always the result of the ideomotor response. This is involuntary movement caused by thoughts rather than sensory stimulation, and the dowser is unknowingly moving the stick. The experience can be profound since an outside force seems to be acting on the object.

Belief in dowsing requires post hoc reasoning, the notion that because one event happens after another, the two are necessarily related. The stick shakes, water is found, therefore it works. Dowsers can relate their experiences to fellow practitioners, stoking the confirmation bias. But tests, not testimonies, are what constitute proof.

The first recorded experiment was in 1641, with poor results for the dowsing camp. Over three centuries later, the American Society for Psychical Research tested 27 dowsers, all of whom failed miserably. By contrast, a geologist and engineer team went 16-for-16 in the same field. Other tests have been done by Nature and the Skeptical Inquirer, with participants never performing better than chance.

In a challenge posed by James Randi, three dowsers attempted to find water in underground pipes. Any tester achieving an 80 percent success rate would be given $10,000. All failed. With the prize now at $1 million, and with so many persons convinced they have the ability, dowsers are the most frequent claimants to the James Randi Challenge. None has won the money, and Randi reports reasons given for the failures have included too much noise, too much silence, the wrong temperature, high humidity, planet misalignment, and an upset stomach.

As the engineer and geologist example from 1949 shows, there would be little need for dowsing even if it worked. So the artificial art has entered the modern era and its purported abilities amplified. Digital dowsers now offer rods with ergonomic plastic handles, notional electronic circuitry, and a scientific look and name.

One was the DKL Remote Heartbeat Detector. Its manufacturer claimed it could pick up a person’s pulse from 500 yards away in the open, or through several yards of thick concrete and rubble. It was marketed as a way to find missing children or victims of collapsed buildings. The device was a fraud, but even if worked, it would have failed since it would have picked up the heartbeat of the operator instead.

Before being shut down by the FBI, the Qaudrop Corporation sold its QRS 250G Detector to police departments and schools. The company claimed the device could find drugs, weapons, or whatever else the customer wanted it to, including oil, minerals, and golf balls. When scientists at the Southwest Research Institute got their hands on one, they found its insides to be just epoxy and dead ants.

For those both gullible and greedy, we have the Treasure King System 2000. The company hails it as “An operator body response long range locating and tracking instrument.” With that description, there’s no telling what it’s supposed to do or if it’s working. But as an additional cover, the company cautions if no treasure is found, the user lacks conductive abilities. So, if it works, we did it. If it fails, you did it.

Then we have the GT200, which Mexican defense officials used to root out drug traffickers. The device was a mix of ersatz electronics, the ideomotor response, and the operator’s conscious movements. On a highway outside Monterrey in 2009, the device “pointed” to a car, and Soldiers swarmed. In this case, the device worked and drugs were found: A bottle of Tylenol. This was presented as evidence of how thorough and hypersensitive the GT200 is.

Pilfering of taxpayer money and frightening innocent motorists are minor compared to what happened in Thailand. Although the GT200 was advertised in Mexico as a means to ferret out drugs, in Thailand it was marketed as explosives detector. At least four persons died after using the device and proceeding when it failed to detect explosives that were present.

The GT200 has been put out of business, but there are several devices competing for its share of the market. And like the wishbone sticks of yore, none of them hold water.