Biology, Science, Scientific Method

Placebo Effect

One important way that we learn the facts in the world around us is through studies, where a scientist tests a hypothesis to see if it is true or not. For a meaningful study, researchers must collect reliable results. This is particularly difficult in human based studies because people can perceive and even manifest improvements without actual medical treatment, a phenomenon known as the placebo effect.

The placebo effect speaks to the mind’s ability to effect the body without any constructive action taken. Pills, creams, devices, sham surgeries, sham acupunctures, and even being told “you will feel better” can all have placebo effects despite doing nothing constructive. Conversely, receiving treatment without knowing it can lessen the effects of that treatment. The effects are strongest in subjective results—such as describing pain—and weakest in objective results—such as blood pressure.

Expectancy is an important part of the placebo: if the subject is expecting positive effects, they will look for these effects. Some might think that this could justify tricking patients with placebos for noninvasive results. The danger of this, however, is that it involves deception on the part of the doctors, which is why it is not considered a treatment, but actually a tool.

Prescribing pure placebos is bad medicine. Their effect is unreliable and unpredictable and cannot form the sole basis of any treatment

- The United Kingdom Parliamentary Committee on Science and Technology

Instead, placebos have become a tool in scientific research to exclude results that may be the product of the placebo effect and not the medicine itself. In a crossover study, each subject experiences both the tested substance and a placebo. This way, the results from the period when they were receiving the tested substance can be compared to the placebo period, isolating the results that were simply the result of the placebo effect and making each subject, their own “control.” Thus, while the placebo effect can introduce errors in some experiments, a well designed study can use it to establish constructive and consistent treatments.


Placebo.” Wikipedia. Wikimedia Foundation, 31 Aug. 2013. Web. 01 Sept. 2013.

UK Parliamentary Committee Science and Technology Committee. “Evidence Check 2: Homeopathy”

Learn More

“Against Depression, a Sugar Pill Is Hard to Beat”. The Washington Post. May 7, 2002.

Silberman, Steve. “Placebos Are Getting More Effective. Drugmakers Are Desperate to Know Why.” Conde Nast Digital, 24 Aug. 2009. Web. 03 Sept. 2013.

Tirrell, Meg (24 October 2012). “Genetics May Help Explain Placebo Effect, Researchers Say“. Bloomberg. Retrieved 1 November 2012.

Also learn about:

Nocebo [wikipedia]
Meaning Response” [Deconstructing the Placebo Effect and Finding the Meaning Response]
The “Placebo Paradox” [ David H. Newman (2008). Hippocrates’ Shadow. Scribner. pp. 134–59. ISBN 1-4165-5153-0.]
Honest Placebo” effect [Kaptchuk TJ, Friedlander E, Kelley JM, et al. (2010). “Placebos without Deception: A Randomized Controlled Trial in Irritable Bowel Syndrome”. In Boutron, Isabelle. PLoS ONE 5 (12): e15591.]
Classical conditioning [wikipedia]


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