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Through my involvement in the skeptical community, I have learned just how susceptible we all are to bias, particularly confirmation bias.

Confirmation bias is the tendency we all have to pay more attention to information that confirms what we already believe to be true, and to pay less attention to information that contradicts our beliefs. This is seen widely, from politics to religion — and everything in between.

For example, the full moon is thought by many to have effects on everything from violence and suicide to accidents and mental illness. Even words such as lunatic and lunacy come from the Latin word for moon, luna. One may sometimes hear professionals working in a hospital’s hectic emergency room exclaim, “It must be a full moon.” However, when one studies the effect of the moon phase on any of these factors, these supposed effects evaporate.

So why do these beliefs persist despite proof to the contrary? Confirmation bias certainly plays a role. For instance, if one already believes that the full moon makes for a busy night in the ER, when one looks out the window on one such hectic night and sees a full moon, this belief will be reinforced. However, little attention is granted to the hectic nights that fall on nights when the moon is not full, or on full moon nights when there is very little activity in the ER. In this way the belief is perpetuated, even when the effect is imaginary.

If we want our beliefs to accurately reflect reality, we must take care to guard against bias, while realizing that it may not be possible to remain completely unbiased.

For example, in quality scientific research the preferred research method is called a double-blind, placebo-controlled trial. Under this methodology, a pool of subjects is split in two. The first group gets an intervention (a medication, procedure, etc.), while the second group gets a placebo (a fake intervention, such as a tablet that contains no active ingredient). This is done so random variations in the study group can be controlled for, by comparing the active intervention group to the control group.

Double-blind means that neither the researchers nor the subjects know which individuals are receiving the intervention and which are not. Scientists discovered long ago that experiments could be swayed dramatically when a subject’s or researcher’s bias and expectation bled into the study, and only by removing this bias could the true effect of the interventions be gleaned.

Blinding is also an essential tool in the skeptic’s toolbox; incredibly simple, yet often overlooked by most. This was realized by an 11-year-old named Emily Rosa, who designed a test to see whether practitioners of “therapeutic touch” (a practice that claims to heal through the manipulation of a subjects’ aura) could detect a person’s aura, because they claim to be able to manipulate it. Once the practitioner was blinded, it became clear that she could not even detect whether a person was in front of her hands, let alone manipulate this imaginary energy field.

Blinding reveals the Ouija board to be nothing more than a child’s toy once the users are blinded and gibberish comes forth from the planchette. The supposed abilities of psychics, who use nothing more than cold reading techniques, disappear when they are blinded. Deprived of the feedback and response of the individual being read, the psychic is left to engage in pure guessing or vague platitudes.

Dowsers also do no better than chance when they are blinded. Dousing is the practice of locating underground water (or anything invisible) by observing the movement of a pointer, often a forked stick or bent wires. While belief in this brand of nonsense is typically benign, this is an example of where uncritical thinking can have unforeseen consequences.

About 15 years ago, a company named ATSC began selling a device called the ADE 651, which is now described as a glorified dowsing rod. The device was claimed to be able to locate everything from ivory and narcotics to guns and explosives. The company’s founder, Jim McCormick, sold these “devices” to many, including governments. The Iraqi government reportedly spent more than $40 million on these products, to use at checkpoints to locate bombs. It is tragic to think of how many explosives were smuggled past soldiers relying on a dowsing rod for national security.

In 2013, McCormick was sentenced to 10 years in prison for fraud. To think, all of this expense and risk could have been avoided if the purchaser had simply subjected the device to a blinded test.

By acknowledging our own biases and how they can influence our understanding of the world, and through the use of blinded testing, can we come closer to the truth.

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Jeremy Fejfar is a member of the La Crosse Area Freethought Society.


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(10) comments


Nice article Jeremy! Two more examples: PERSONAL: We tried to reproduce a method that would have expanded our research. We got the inventor of the method to come show us his method (at our expense from Europe) after all our attempts failed. We observed him and suspected that he was a fraud. We insisted that we confirm the data using a double-blind protocol. There was no difference between the experimentals and controls. We sent the data to his mentors and told them of our suspicions. He was caught fabricating data there and was booted out of graduate school.
SECOND: This concerns a well known homeopathy method - water memory. The results got published in the peer reviewed journal, Nature! When scientists repeated the experiments (the Amazing Randi was involved) using a double-blind protocol; the effect disappeared (see and for detailed information).

The double-blind protocol rules!


patsy, you don't really get sarcasm do you?


Tower - you just proved his point - And you called me an idiot?


great job, I will keep a copy to this! for some reason it his often difficult to get people to understand this. thanks!


I just hear NBR on this one. He looks Muslim, can we trust him? His name is also foreign. I wonder if he is a refugee or better yet a product of the Annukian earth landing. :-)


Great column, Jeremy! While scientists must try to eliminate confirmation bias, the majority of people don't - especially when discussing the biggest scam of all, religion.


This is the most important and telling essay to date in this series. Confirmation bias is universal, at least to a degree, and colors all our opinions. It is possible to guard against this to a large degree, as you state, completely, I am not so sure. Any person interested in objective truth should be interested in understanding "confirmation bias".

Jeremy, I have relocated permanently to SW Florida. I have posted your link to all my International friends/colleagues, most of whom are globally interested educators, for their edification. So, your wisdom and insights are now being read around the world.


Confirmation bias. All my friends, conservative, moderate, and liberal -- this is must reading -- we are all guilty.




JF: "Confirmation bias is the tendency we all have to pay more attention to information that confirms what we already believe to be true."

Cash bias "is the tendency we all have to pay more attention to" whatever scam we're currently involved in: the Vatican with their indulgences, the Scientologists with their E-meters (or whatever), the televangelists with their loopy TV sermons (Kenneth Copeland even has his own airport).

Therefore, if your crackpot religious or mystical scam buys you a nice airport, go bias yourself silly.

“Mr. Lollipop, do I look like a sucker to you?”
― Jarod Kintz, This Book is Not FOR SALE

“One who makes himself a worm cannot complain afterwards if people step on him.”
― Immanuel Kant

“It's morally wrong to allow a sucker to keep his money.”
― W.C. Fields

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