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Thanks to XKCD, I have been paying more attention to hand dryers. Randall Munroe points out (via aircraft-towed aerial billboard) that the hand dryer feels cold because the water on your hands is evaporating. That’s true even if the air is quite hot. But that’s the best-case scenario with hand dryers. I’ve run into plenty that definitely do not have warm air. And I’ve also encountered empty paper towel dispensers that I thought were touchless blower hand dryers and waved my hands around wildly under them. My frustration has become art by way of MidJourney. Let’s talk about placebos.

1. Placebo Controlled Trials

The gold standard biomedical experiment is the double-blind randomized placebo controlled clinical trial. That’s a very long technical thing. It means that a lot of trouble was taken to only measure the effects of the treatment (not the power of positive thinking, not the doctor’s optimism, not how well the treatment can be targeted to the people who will respond). The data gets logged without bias. Was the outcome caused by the drug? Was it due to luck? Was it due to psychological effects from getting a pill in a clinic? That all gets subtracted.

2. Benefits of Placebos

This is crazy – why do we have to go to so much trouble? It turns out that the placebo effect can be pretty powerful. There’s a great story in an article called “Placebos and placebo effects in medicine: historical overview” (link below). In 1801, doctors put metal rods in contact with the body to cure many ailments. The electromagnetic influence of the metal was supposed to help all kinds of things. It turns out that those copper bracelets and magnetic energy masks have been a known scam for 200 years. A physician named John Haygarth replaced the metal rods with wooden rods that looked similar. The same percentage of patients reported relief of symptoms. What’s remarkable is that the percentage was 80%! Four out of five people thought the rods helped! Whatever is causing people to report a benefit, it’s not the electromagnetic properties of the rods.

Haygarth wrote this about the incident: “an important lesson in [medicine] is here to be learnt, the wonderful and powerful influence of the passions of the mind upon the state and disorder of the body. This is too often overlooked in the cure of diseases.” He did not take this as a sign of the uselessness of the metal rods, but rather the usefulness of deception in manipulating the psychology of the patient.

And it was worse than that! They thought they were manipulating vulnerable people. “The value of placebo was thought inversely related to the intelligence of the patient; the use of a medical ritual was more effective and necessary for ‘unintelligent, neurotic, or inadequate patients.’” It turns out to be false, though. We are all susceptible to the placebo effect. Even when we know the truth, placebos can produce a measurable difference from a no-treatment control group.

Given all of that, it is important to subtract that effect from any reported effectiveness of a drug.

3. A Poisonous Idea: The Nocebo Effect

I read a sensational account of the opposite of the placebo effect: the nocebo effect. Where the placebo is the beneficial effect of a neutral treatment, the nocebo effect is the pathogenic effect of a neutral treatment. A nocebo produces sickness through the expectation of sickness.

Helen Pilcher wrote an article, “The Science of Voodoo: When Mind Attacks Body” (link below). She tells the story of a man convinced that he was dying from a voodoo curse. He did seem to be rapidly declining in health. He was so sick that his doctor thought he might actually die. Even so, the doctor believed that it was purely the patient’s mind that was destroying his body. His treatment was to perform a slight-of-hand deception.

The physician told the patient that he was sick because the voodoo priest had caused a lizard to grow in his belly. This imaginary lizard was said to be chewing on the victim’s organs. The physician administered the “cure,” which was just a drug that caused the patient to vomit. The physician slipped a real lizard into the vomit. He made a great show of “finding” the lizard, thereby proving to the patient that the curse was ended.

The effect was immediate relief, and the patient recovered fully.

Consider the psychological power of the voodoo curse. It was so compelling, that the patient might have deluded himself to death.

4. Conclusion

So, given all of that, maybe placebo hand dryers are a great idea and we can just will our hands dry after all. Major benefit: the blower won’t deposit poop bacteria directly on our hands. Major drawback: hands won’t actually be dry, and wet hands transmit germs more effectively.

_{The comic was written and created by Peter Allen with MidJourney and shared under Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) https://creativecommons.org/licenses/by-nc/4.0/}

Further Reading:

De Craen, Anton J M, Ted J Kaptchuk, Jan G P Tijssen, and J Kleijnen. “Placebos and Placebo Effects in Medicine: Historical Overview.” Journal of the Royal Society of Medicine 92, no. 10 (October 1999): 511–15. https://doi.org/10.1177/014107689909201005.

Finniss, Damien G, Ted J Kaptchuk, Franklin Miller, and Fabrizio Benedetti. “Biological, Clinical, and Ethical Advances of Placebo Effects.” The Lancet 375, no. 9715 (February 20, 2010): 686–95. https://doi.org/10.1016/S0140-6736(09)61706-2.

Harvard Health. “The Power of the Placebo Effect,” May 1, 2017. https://www.health.harvard.edu/mental-health/the-power-of-the-placebo-effect.

Miller, Franklin G., and Donald L. Rosenstein. “The Nature and Power of the Placebo Effect.” Journal of Clinical Epidemiology 59, no. 4 (April 1, 2006): 331–35. https://doi.org/10.1016/j.jclinepi.2005.12.001.

Pilcher, Helen. “The Science of Voodoo: When Mind Attacks Body.” New Scientist. Accessed April 7, 2023. https://www.newscientist.com/article/mg20227081-100-the-science-of-voodoo-when-mind-attacks-body/.

“Placebos May Have Benefits, Even When People Know They Are Taking Them,” September 1, 2020. https://www.medicalnewstoday.com/articles/placebos-may-have-benefits-even-when-people-know-they-are-taking-them.

Plassmann, Hilke, and Bernd Weber. “Individual Differences in Marketing Placebo Effects: Evidence from Brain Imaging and Behavioral Experiments.” Journal of Marketing Research 52, no. 4 (August 1, 2015): 493–510. https://doi.org/10.1509/jmr.13.0613.

Rankin, Lissa. “The Nocebo Effect: Negative Thoughts Can Harm Your Health | Psychology Today.” Accessed April 7, 2023. https://www.psychologytoday.com/us/blog/owning-pink/201308/the-nocebo-effect-negative-thoughts-can-harm-your-health.

Huesca-Espitia, Luz del Carmen, Jaber Aslanzadeh, Richard Feinn, Gabrielle Joseph, Thomas S. Murray, and Peter Setlow. “Deposition of Bacteria and Bacterial Spores by Bathroom Hot-Air Hand Dryers.” Applied and Environmental Microbiology 84, no. 8 (April 2, 2018): e00044-18. https://doi.org/10.1128/AEM.00044-18